ICHT & SETD 2008 - IMTmit.imt.si/izvodi/mit086/SSHT_Bled2008.pdfTHE EFFECT OF SERVICE CONDITIONS ON...

2nd INTERNATIONAL CONFERENCE ON THE HEATTREATMENT AND SURFACE ENGINEERING OF

TOOLS AND DIESEXTENDED ABSTRACTS

ICHT & SETD 200825–28 May 2008

Hotel KOMPAS – Bled, Slovenia

SSHT

Slovenian Society for HeatTreatment

CSHTSE

Croatian Society for Heat Treat-ment and Surface Engineering

ASMET

The Austrian Society forMetallurgy and Materials

Institute of Metals and Technology,Ljubljana, Slovenia

IFHTSE

International Federation forHeat Treatment and Surface

Engineering

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ChairVojteh Leskovšek, SSHT, Slovenia

Co-ChairBo�o Smoljan, CSHTSE, Croatia

Co-ChairHeimo Jäger, ASMET, Austria

International AdvisoryCommittee

Yoshinao Mishima, JapanTom Bell, United KingdomDerry Doyle, AustraliaLeszek A. Dobrzanski, PolandReinhold Ebner, AustriaBernhard Edenhofer, GermanyJanez Grum, SloveniaBruno Hribernik, AustriaSture Hogmark, SwedenZoltán Kolozsváry, RomaniaDragomir Krumes, CroatiaBo�idar Lišèiæ, CroatiaAleksander Nakonieczny, PolandDavid Nolan, AustraliaPeter Panjan, SoveniaMassimo Pellizzari, ItalyMario Rosso, ItalyGünter Rübig, AustriaJános Takács, HungaryGeorge Totten, United StatesFranc Vodopivec, SloveniaRobert Wood, United KingdomHans Zoch, Germany

International ProgrammeCommittee

Monika Jenko, Slovenia, ChairFranjo Cajner, CroatiaTomislav Filetin, CroatiaChristian Mitterer, AustriaReinhold Schneider, AustriaMladen Stupnišek, CroatiaT.S.Sudarshan, United StatesJo�e Vi�intin, Slovenia

International OrganisingCommittee

Borivoj Šuštaršiè, Slovenia, ChairDarko Landek, CroatiaHubert Lenger, AustriaBo�idar Matijeviæ, CroatiaDarko Mikec, SloveniaBojan Podgornik, SloveniaSanja Šoliæ, CroatiaVasilij Prešern, Slovenia

Local Organising Committee

Vesna NahtigalSonja JalševacAnton JaklièPaul McGuinessMiro PeèarZdenka RajhIrena Škulj

3

SLOVENIAN RESEARCH AGENCY

Faculty of MechanicalEngineering and NavalArchitecture, Zagreb, Croatia

Rübig GmbH

Sponsors

Special Exhibitors

INSTITUTE OF METALS ANDTECHNOLOGY

ContentsCONTENTS

HEAT TREATMENTPOSSIBILITIES OF HEAT TRANSFER CONTROL DURING QUENCHINGB. Lišèiæ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

THE INFLUENCE OF COOLING RATE AND AUSTENITIZATION TEMPERATURE ON THE MICROSTRUCTURE ANDPROPERTIES OF A MEDIUM CARBON MICROALLOY FORGING STEELM. Abed, A. Zabett . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

THE USE OF NEW TYPES OF LARGE AND MIDDLE SIZE VACUUM BATCH FURNACE FOR THE HEATTREATMENT OF MOULDS AND DIESJ. Ben-Hamida, M. Rink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

TWO-COMPONENT DIFFUSIVE STEEL SATURATIONR. Ivanov . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

HEAT TREATMENT AND WELDING EFFECTS ON MECHANICAL PROPERTIES AND MICROSTRUCTUREEVOLUTION OF 2024 AND 7075 ALUMINIUM ALLOYSH. Maamar, K. Mohamed, R. Otmani Rafik, F. Toufik, D. Nabil, A. Djilali . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

AFFECT OF VIBRATORY WELD CONDITIONING ON IMPACT TOUGHNESS OF WELDB. Puèko. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

THE EFFECT OF AGING PARAMETERS ON PROPERTIES OF MARAGING STEELI. Kladariæ, D. Kozak, D. Krumes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

AUSTEMPERING HEAT TREATMENT EFFECT ON MECHANICAL PROPERTIES OF AISI O1 STEELJ. Vatavuk, L.C.F. Canale, George E. Totten . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

COOLING ASPECTS OF VACUUM FURNACESR. Stein, B. Zieger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

IN-SITU MONITORING OF VACUUM CARBURIZINGM. Bruncko, A. C. Kneissl, Ivan Anzel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

HEAT TREATMENT OF CORROSION RESISTANT TOOL STEELS FOR PLASTIC MOULDINGR. Schneider, J. Perko, G. Reithofer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

HEAT TREATMENT OF HOT WORK TOOL STEELS – SIZE MATTERS!G. Reithofer, T. Collins, R. Schneider . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

DIRECT METHOD OF TRACING OF OXIDATION IN METALS AND ALLOYSI. An�el . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

HEAT TREATMENT OF TOOL STEELSA. Molinari, M. Pellizzari . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

CRYOGENIC TECHNOLOGYTHE EFFECT OF SOME HEAT TREATMENT PARAMETERS ON THE PROPERTIES OF AISI D2C. Henrik Surberg, P. Stratton, K. Lingenhöle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

EFFECT OF DEEP-CRYOGENIC TREATMENT ON HIGH SPEED STEEL PROPERTIESF. Cajner, V. Leskovšek, D. Landek, H. Cajner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

DEEP SUB ZERO PROCESSING OF METALS AND ALLOYS – PART IK. M. Iyer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

DEEP SUB ZERO PROCESSING OF METALS AND ALLOYS – PART IIC. L. Gogte, Kumar M. Iyer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

SURFACE ENGINEERINGCORRELATION BETWEEN SPUTTERING CONDITIONS AND GROWING PROPERTIES OF (TiAl)N/AlNMULTILAYER COATINGSE. Altuncu, F. Üstel. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

EXAMINATION ON SURFACE PROPERTIES OF MODIFIED AISI 1090 STEEL BY PULSE PLASMA TECHNIQUEA. Ayday, A. Özel, C. Kurnaz, M. Durman . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

IMPACT WEAR RESISTANCE OF LASER-CLAD VALVE SEATS WITH STELLITE 6 ALLOYS. S. Chang, H. C. Wu, Chun Chen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

OBSERVATION MULLITE STRUCTURE DEPENDING ON SPRAYING PARAMETERSG. Erdogan, F. Ustel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

CHARACTERISTICS OF ELECTROCODEPOSITED Ni–Al�O� NANO PARTICLE REINFORCED METAL MATRIXCOMPOSITE (MMC) COATINGSH. Gül, F. Kiliç, S. Aslan, A. Alp, H. Akbulut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

ICHT & SETD 2008 CONTENTS

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FABRICATION AND CHARACTERIZATION OF Ni–SiC METAL MATRIX COMPOSITE (MMC) NANO-COATINGS BYELECTRODEPOSITIONF. Kiliç, H. Gül, S. Aslan, A. Alp, H. Akbulut . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

SURFACE MODIFICATION OF LOW AND MEDIUM CARBON STEEL BY USING ELECTROLYTIC PLASMATHERMOCYCLIC TREATMENTL. C. Kumruo

�

glu, A. Ayday, A. Özel, A. Mýmaro�

glu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

MAGNETIC-ASSISTANCE IN CYLINDER-SURFACES FINISHP.S. Pa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

STRUCTURAL CHARACTERISTICS OF PLASMA NITRIDED 32CrMoV33 HOT WORKING DIE STEELA. Turk, C. Býndal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

THE EFFECT OF BIAS VOLTAGE ON OXIDATION BEHAVIOR OF MONOLAYER TiAlN AND MULTILAYERTiAlN/AlN COATINGSF. Üstel* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

PROPERTIES OF HARD Ni-P-Al�O� AND Ni-P-SiC COATINGS ON Al-BASED CASTING ALLOYSD. Vojtìch. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

INVESTIGATION OF SPUTTER CRATERS AFTER GDOES ANALYSIS OF TiCN COATINGSP. Panjan, Ð. Goršæak, M. Èekada, L. Æurkoviæ* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

PREVIOUS OR SUBSEQUENT ELECTRON BEAM HARDENING OF THERMOCHEMICAL TREATED AND PVD HARDCOATED STEELS FOR TOOLS AND COMPONENTSG. Sacher, R. Zenker, H.-J. Spies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

MICROSTRUCTURAL AND TRIBOLOGICAL INVESTIGATION OF AlTiN-COATED CONVENTIONAL AND POWDERMETALLURGY COLD WORK TOOL STEEL SUBSTRATESP. Panjan, Ð. Goršæak, L. Æurkoviæ, M. Èekada . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

PLASMA NITROCARBURIZING OF AISI H-13 STEEL FOR IMPROVED ABRASION RESISTANCEG. E. Totten, L.C. Cassteletti, R.M. Muñoz Riofano, A. Lombardi Neto. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

CONTEMPORARY INDUSTRIAL APPLICATION OF NITRIDING AND ITS MODIFICATIONSJ. Michalski, P. Wach, J. Tacikowski, M. Betiuk, K. Burdyñski, S. Kowalski, A. Nakonieczny . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

INFLUENCE OF ION ETCHING IN LOW PRESSURE ARC DISCHARGEIN PLASMA ON DUPLEX COAT ADHESION PRODUCED BY GAS NITRIDING AND PA PVD-ARC PROCESSESM. Betiuk, J. Michalski, K. Burdynski, P. Wach, A. Nakonieczny . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

STATE OF THE ART DEPOSITION TECHNOLOGIES AND COATINGS FOR TOOL AND DIE APPLICATIONSF. Papa, T. Krug, R. Tietema . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

DEVELOPMENT OF OPTIMAL PVD NANO-COMPOSITE COATINGS FOR ALUMINIUM ALLOY DIE CASTINGAPPLICATIONSD. Ugues, E. Torres, M. Perucca . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78

ENHANCEMENTS OF THERMAL FATIGUE RESISTANCE OF HOT WORKING TOOLING: THE ROLE OFMATERIALS, HEAT TREATMENTS AND COATINGSM. Rosso . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

NOVELITY IN DIFFUSION COATING TECHNOLOGYB. Matijeviæ, M. Stupnišek . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

THERMAL STABILITY AND AGE HARDENING OF METASTABLE HARD COATINGSP. H. Mayrhofer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

HARD COATINGS FOR DIES AND MOULDSJ. Kiefer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

POSSIBILITIES OF STRENGTHENING OF DIFFUSION NITRIDED LAYERS BY SHOT-PEENINGA. Nakonieczny, I. Pokorska . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

NITROOXIDATION OF TOOLS MANUFACTURED FROM HIGH-SPEED STEELT. Babul, Z. Obuchowicz, W. Grzelecki . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

MECHANICAL AND PHYSICAL PROPERTIES OF TOOL AND DIE MATERIALSTOOLS MATERIAL BEHAVIOR AT ELEVATED TEMPERATURESJ. Brniæ, M. Èanaðija, G. Turkalj, D. Lanc, T. Pepelnjak, B. Barišiæ, G. Vukeliæ, M. Brèiæ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

BEHAVIOUR AT ELEVATED TEMPERATURE OF 55NiCrMoV7 TOOL STEELM. G. De Flora, M. Pellizzari . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

MODERN PRE-HARDENED TOOL STEELS IN DIE-CASTING APPLICATIONSP. Hansson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

INNOVATIVE TESTING METHOD FOR THE EVALUATION OF THERMAL SHOCK AND MECHANICAL WEARS. Harksen, W. Bleck . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

HEAT-RESISTANT CASTINGS IN CARBURISING FURNACEB. Piekarski . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

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FRACTOGRAPHIC EVALUATION OF GIGACYCLE FATIGUE FAILURE OF A HIGH Cr ALLOYED COLD WORKTOOL STEELC. R. Sohar, A. Betzwar-Kotas, C. Gierl, B. Weiss, H. Danninger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

ANISOTROPY EFFECTS ON GIGACYCLE FATIGUE BEHAVIOR OF 12%CHROMIUM ALLOYED COLD WORK TOOLSTEELC. R. Sohar, A. Betzwar-Kotas, C. Gierl, B. Weiss, H. Danninger . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106

LOAD ON PUNCH DURING FINEBLANKING INCONEL 718D. Èesnik, M. Bizjak, J. Rozman. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

THE EFFECT OF SERVICE CONDITIONS ON CRACK INITIATION AND PROPAGATION IN WELDED JOINT OFHIGH-ALLOY STEEL X20M. Burziæ, D. Gaèo, D. Burziæ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

MECHANICAL PROPERTIES OF BORONIZING STEELS AS REPERCUSSION OF BORON PHASESD. Krumes, I. Kladariæ, I. Vitez . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112

EFFECT OF HEAT TREATMENT ON THE MECHANICAL PROPERTIES OF TOOL STEELSR. Ebner, S. Marsoner, W. Ecker, M. Leindl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114

DETERMINATION OF LOWER BOUND OF FRACTURE TOUGHNESS OF SUSPENSION SPRING MATERIALN. Gubeljak, J. Predan, B. Senèiè, J. Vojvodiè Tuma, M. Jenko . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116

ADVANCED TOOL MATERIALSFATIGUE RESISTANT PM TOOL STEELSZ. Devrim Caliskanoglu, J. Perko, H. Lenger. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119

DEVELOPMENT OF A HYBRID TOOL STEEL PRODUCED BY SPARK PLASMA SINTERINGM. Pellizzari, M. Zadra, A. Fedrizzi . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121

STRESS STATE OF 12% Ni MARAGING STEEL AFTER A MODIFIED PROCEDURE OF PRECIPITATIONHARDENINGJ. Grum, M. Zupanèiè . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123

TRIBOLOGYWEAR BEHAVIOUR OF PLASMA – SPRAYED Al-12Si/SiC COMPOSITE COATINGS UNDER DRY AND WATER –LUBRICATED SLIDINGS. Akgün, S. ªahin, F. Üstel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

ANALYSIS OF ABRASIVE WEAR RESISTANCE OF THE D2 TOOL STEEL IN RELATION TO HEAT TREATMENTD. Gorscak, T. Filetin, K. Grilec, M. Godec, D. Kapudija . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131

INFLUENCE OF DEEP-CRYOGENIC TREATMENT ON TRIBOLOGICAL PROPERTIES OF P/M HIGH-SPEED STEELB. Podgornik, V. Leskovšek, J. Vi�intin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

WEAR RESISTANCE OF THIN PROTECTIVE LAYERS IN ABRASION CONDITIONS UNDER HIGH-PRESSURESV. Marušiæ, G. Mariæ. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135

EVALUATION METHODS AND SURFACE ENGINEERING TECHNIQUES FOR IMPROVED GALLING PROPERTIESOF FORMING TOOLSJ. Vi�intin, B. Podgornik . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

INFLUENCE FROM TOOL ROUGHNESS ON THE RISK OF WORK MATERIAL ADHESION AND TRANSFERM. Hanson, S. Hogmark, S. Jacobson . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

APPLICATIONS OF NANOTECHNOLOGYCHARACTERIZATION OF MULTILAYER PACVD COATINGS FOR HOT-WORKED TOOL STEELS USING ELECTRONSPECTROSCOPY TECHNIQUESM. Jenko, V. Leskovšek, J. T. Grant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

DESIGN OF RECYCLE PROCESS OF COLOR FILTER USING ARC-FORM TOOLP.S. Pa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

MATHEMATICAL MODELLING AND PROCESS SIMULATIONGENETIC PROGRAMMING AND JOMINY TEST MODELLINGM. Kovaèiè . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

PREDICTION OF HARDNESS DISTRIBUTION WITHIN AXIALLY SYMMETRICAL WORKPIECES THEREUPONHIGH PRESSURE GAS QUENCHINGB. Lišèiæ, T. Filetin, T. Lübben, D. Landek, D. Lisjak . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

UTILIZATION OF THE KUYUCAK METHOD TO SIMULATE LABORATORY AND COMMERCIAL QUENCHINGPROCESSESG. E. Totten, G. Sánchez Sarmiento, R. M. Muñoz Riofano, L. C.F. Canale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

COMPUTER SIMULATION OF MECHANICAL PROPERTIES OF STEEL DIESB. Smoljan, S. Smokvina Hanza, D. Iljkiæ, G.E. Totten, I. Felde . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

ICHT & SETD 2008 CONTENTS

7

RAPID PROTOTYPING OF TOOLS AND DIESPOTENTIALS OF LENS TECHNOLOGYI. Palèiè, M. Bala�ic, M. Milfelner, B. Semoliè, B. Buchmeister . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159

MICROSTRUCTURE AND MECHANICAL CHARACTERISTICS OF DMLS TOOL-INSERTSB. Sustarsic, S. Dolinsek, M. Godec, M. Jenko, V. Leskovšek . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

APPLICATIONS AND MATERIAL SELECTION FOR TOOLS AND DIESIMPORTANCE OF SELECTION OF THE TOOL STEEL GRADES AND PVD COATINGS IN COLD WORK TOOLSD. Gorscak, T. Filetin, D. Cackovic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

EXPERIMENTAL ANALYSES OF THE INFLUENCE ON CORROSIVE ENVIRONMENT IN SEAWATER OF VLORE BAYTO THE CENTRE ON FATIGUE OF STEEL A -3V. Kasemi, A. Haxhiraj . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169

SELECTION OF TOOL MATERIALS FOR COLD FORMING OPERATIONS USING A COMPUTERIZED DECISIONSUPPORT SYSTEMI. Czinege, T. Réti, I. Felde . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171

AN ANALYSIS OF RELATIONSHIPS BETWEEN BEHAVIOUR AND MICROSTRUCTURE CONSTITUTION OFHOT-WORK TOOL STEELB. Smoljan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172

HEAT TREATING OF H13 DIES ACCORDING TO THE NADCA AND GM POWERTRAIN SPECIFICATIONT. Wingens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174

BODYCOTE, GLOBAL LEADER IN THERMAL PROCESSINGT. Wingens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174

CONTENTS ICHT & SETD 2008

8

HEATTREATMENT

HEAT TREATMENT

POSSIBILITIES OF HEAT TRANSFER CONTROLDURING QUENCHING

Bo�idar LišèiæFaculty of Mechanical Engineering and Naval Architecture, University of Zagreb, Croatia

EXTENDED ABSTRACT

Quenching is a nonstationary thermodynamic process theaim of which is to attain the required level of superficialhardness,as well as adequate hardness distribution on thecross-section of a hardened workpiece, with minimumdeformation and size change. These two requirementsare opposite to each other. A higher quenching intensityto achieve greater depth of hardening increases deforma-tion and size change.Therefore it is necessary to controlthe dynamics of heat extraction from the workpiece i.e.to optimize the quenching parameters and control thequenching intensity during the whole quenching process.From the first moment when a workpiece is immersed ina quenchant, three different processes start and developsimultaneously:the thermodynamical one (heat extrac-tion), the metallurgical one (microstructure transforma-tion) and the mechanical one (stress and strain develop-ment).The transformation of the microstructure does notstart on the whole cross-section simultaneously,but grad-ually from the surface to the core only then when a par-ticular point attains the temperature A�. This fact makesit possible (at least for bigger cross-sections) to inten-tionally change the heat extraction dynamics i.e. to con-trol the quenching process.For numerical simulation of every quenching process itis necessary to know the temperature dependent heattransfer coefficient (HTC), which depends on many in-fluential factors: geometrical, fluid-dynamical, material’sdependent and surface condition’s dependent. There is afundamental difference between the HTC for quenchingin liquid quenchants and for gas quenching.The usual

way to calculate the HTC is to measure the temperatureat a point below surface of a specimen or probe and byapplying the inverse heat conduction method to calcu-late the heat flux on the surface and the surface tempera-ture. For estimation of the HTC one needs to know: thecooling curve at the location where the temperature ismeasured, thermophysical properties of the workpiece’smaterial and the temperature of the quenchant.It is im-portant to distinguish between the HTC calculated forthe small laboratory test specimen and for realworkpieces. The HTC calculated for small laboratorytest specimen cannot be used for quenching simulationof real workpieces in practice because of the followingreasons: real workpieces have bigger mass ( in case ofcylindrical parts have bigger diameters); their coolingtimes are much longer, and some parameters which oc-cur in practice (bath temperature,agitation rate and direc-tion, position and loading arrangement in a batch) cannotbe taken into account at laboratory tests. Therefore forcalculation of HTC in case of real cylindrical workpiecesthe Liscic/ Nanmac quench probe was used. It is a cylin-der of 50 mm diameter and 200 mm length instrumentedwith three thermocouples (TC) the outher of which ofspecial design (U.S.Patent No.2,829.185) measures thetemperature at the very surface.By applying the Temper-ature Gradient Method the heat flux density and theHTC can easily be calculated. To calculate realistic val-ues of HTC for workpieces in practice the quenchingprobe should be of the same shape as the workpiece (cyl-inder; plate; ring) and of similar dimensions (volume tosurface ratio). The TC should have the smalles possiblediameter and its position should be as close to the sur-face as possible, in order to minimize the damping effect,the time lag and the TC response time.Changing intentionally the heat extraction dynamics dur-ing quenching in liquid quenchants, especially whenworkpieces of thin cross-sections are involved, is practi-cally impossible or limited to special quenching tech-niques. Two of such examples are: Intensive Quenchingand Delayed Quenching.At Intensive Quenching usu-ally plain water is used but its flow velocity is extremelyhigh, so that(at the IQ-3 variant) from the beginning ofquenching eliminates the film as well as the boilingphases.As a consequence suddenly a hardened crustaround the workpiece is formed in which high compres-sive stresses exist. The most important feature of this

2�� INTERNATIONAL CONFERENCE ON HEAT TREATMENT AND SURFACEENGINEERING OF TOOLS AND DIES

Bled, 25–28 May 2008

11

* Name: Bo�idarLast Name: LišèiæTitle: Prof.Dr.Position: Croatian Academy of Sciences and ArtsInstitution: Faculty of Mechanical Engineering and NavalArchitecture, University of ZagrebAddress: Zrinjski trg 11Address ZIP: 10000City: ZagrebCountry: CroatiaPhone: ++385 1 485 6 571Fax:Email: [email protected]: POSSIBILITIES OF HEAT TRANSFER CONTROLDURING QUENCHINGAuthor: Bo�idar LišèiæTopic: A – Heat treatmentPresentation type: Plenary lecture

technology is the interruption of cooling at the momentwhen the compressive stresses attain its maximum. Asthe results from practice prove, the distortion of parts isless and the fatigue-strength is increased so that theworking life of workpieces is substantially increased,even if lower alloyed steels are used. At DelayedQuenching the first part is slow cooling (usually in air)followed by immersing the workpiece in a liquidquenchant. The cooling rate within the surface region islow, but after immersion in a liquid quenchant it be-comes high during the period when the structure trans-formation in the core takes place.The characteristic fea-ture of this technology is the discontinuous change ofcooling rate. From the earlier works of Shimizu andTamura it is known that the pearlite transformation incase of discontinuous change of cooling rate differs fromwhat it should be according to the CCT diagram, and de-pends on the consumed incubation before the discontinu-ous change of cooling rate occured. They have alsogiven explanation why at delayed quenching an inversehardness distribution on the workpiece’s cross-section(i.e.higher hardness in the core than at the surface) canoccur. Recent investigation by Liscic and Totten hasshown that Polyalkilen-Glykol (PAG) solution of highconcentration can be used for a preprogrammed and re-producible delayed quenching. The results of this inves-tigation enable two important conclusions.The first is:the dynamic of heat extraction at quenching is responsi-ble for the hardness distribution achieved. The secondone is: a controlled delay quenching has a much greaterpotential to achieve through-hardening, compared toconventional quenching process.Gas Quenching. High Pressure Gas Quenching (HPGQ)in vacuum furnaces is a modern and promising technol-

ogy with many advantages compared to liquidquenchants. Cooling takes longer time, hence somequenching parameters can be intentionally changed dur-ing quenching. Because cooling follows the Newton’slaw there is no uncontrollable changes in heat transfer.The main shortcoming of HPGQ, especially at work-pieces of big cross-section made of steel having lowhardenability, is the inability to attain the required hard-ness in the core, due to insufficient quenching intensity.According to the Newton’s law there are two possibili-ties to remedy this situation. The first one is to increasethe heat transfer by increasing the gas pressure and itsvelocity, which is usually applied but is limited becauseof economical reasons (furnace design and blower’spower required). The other one is to increase the temper-ature difference between the workpieces’ surface and thecirculating gas by transient spraying with liquid nitrogenwhich suddenly increases the heat flux, because of thevery low temperature of evaporated nitrogen. By usingboth possibilities simultaneously i.e.a combination ofmain gas stream (of adequate pressure and velocity) andtransient spraying of liquid nitrogen, new ControllableHeat Extraction Technology (CHE) can be developed. Itwould enable a broad spectrum of quenching intensitiesand eliminate the above described shortcoming of theHPGQ. While the change of gas pressure or of its veloc-ity requires a certain period of time, spraying of liquidnitrogen can start and be interrupted momentarily, whichenables a very flexible control of the quenching inten-sity. Moreover providing that the furnace is equippedwith necessary control system and software programme,fully automatic control of the heat extraction duringquenching is possible.

HEAT TREATMENT ICHT & SETD 2008

12

HEAT TREATMENT

THE INFLUENCE OF COOLING RATE ANDAUSTENITIZATION TEMPERATURE ON THE

MICROSTRUCTURE AND PROPERTIES OF A MEDIUMCARBON MICROALLOY FORGING STEEL

Morteza Abed*, Ahad Zabett

ABSTRACT

A practice was carried out to evaluate the influence of austenitization temperature and cooling rate on themicrostructure and mechanical properties of medium carbon microalloyed steel. After austenitization at two tempera-ture of 1100 °C and 1300 °C the microalloyed steel specimens were cooled to various schedules in order to study theinfluence of cooling rate and austenitization temperature on the characteristic of microstructure and some mechanicalproperties. The yield and tensile strength and hardness values were determined. The volume fraction of ferrite andpearlite as the function of cooling rate and austenitization temperature was followed by optical microscopy using MIPtechnique. The results signify that by increasing the cooling rate both strength and hardness increase. Also the volumefraction of ferrite is increased by increasing the cooling rate. Increasing the austenitization temperature seems to raisethe both strength and hardness and also volume fraction of ferrite.

13


Bled, 25–28 May 2008

* Name: mortezaLast Name: abedTitle: M.Sc.Position:Institution: ferdowsi unuversity of mashhadAddress: kavir co, asadabsdi 3, asadabadi st.Address ZIP: 96196City: sabzevarCountry: iranPhone: 09151710797Fax: 05172297289Email: [email protected]: The influence of cooling rate and austenitization temperatureon the microstructure and properties of a medium carbonmicroalloy forging steelAuthors: morteza abedTopic: A – Heat TreatmentPresentation type: Poster

HEAT TREATMENT

THE USE OF NEW TYPES OF LARGE AND MIDDLESIZE VACUUM BATCH FURNACE FOR THE HEAT

TREATMENT OF MOULDS AND DIES

Jamel Ben-Hamida*, Matthias RinkIpsen International GmbH, Flutstrasse 78, 47533 Kleve / Germany

ABSTRACT

Vacuum heat treating of tools and dies under demands of optimized parts properties and less distortion is one of themost important goals in vacuum furnace technology actually. Due to optimized cooling conditions grain boundaryprecipitation leading to shorter die life can be avoided.

This presentation describes the vacuum heat treating of moulds and dies in the Ipsen newly developed Turbo²TreaterM and SuperTurbo™ vacuum furnace under different nitrogen gas quenching conditions.

Keywords: vacuum heat treatment, high pressure gas quenching, less distortion, GMPT 16" H13-standards

1 INTRODUCTION

With the increased use of high-pressure gas quenchingand faster quench rates for moulds and dies, the qualityof heat treatment has improved significantly over the lastdecade.The demands are focused on distortion control, espe-cially on large die inserts, as minimizing distortion savesmoney on post machining. The disadvantage is that lowdistortion is mostly realized through a very slow gasquench, which consequently results in precipitation ofgrain boundary carbides and a shorter die life due to re-duced impact toughness (Figure 1).For many applications GM POWERTRAIN StandardSpecification DC-9999-1 is the key criterion for the per-formance of vacuum furnaces. Its definition is as fol-lows:“DC-9999-1 is the standard procedure and specificationthat ensures the quality of all H-13 and other hot worktool materials and their heat treatment as required for theGM tooling projects.”

Beside the requirements relative to the material in termsof chemical analysis and quality, the test piece and theheat treating cycle parameters and the testing procedureare specified very clearly there. In That way approvedmaterial suppliers, heat treating companies and testinglaboratories are acceptable to GM only.

2 EXPERIMENTS

The test piece consists in a cube of premium grade H-13steel (Mat. No. 1.2344 = X 40 Cr Mo V 51), size16"x16"x16" (approx. 400mm edge length) and weigh-ing 1173 lbs (approx. 532 kg).The Heat treatment of that bloc is described very pre-cisely and is shown in (Figure 2).As to GMPT DC 9999-1 the heat treatment process hasto comply with various requirements, like location of theload thermocouples, preheating procedure, Austenitizing

14


Bled, 25–28 May 2008

* Name: JamelLast Name: Ben-HamidaTitle: Mr.Position: Regional Sales ManagerInstitution: Ipsen International GmbHAddress: Flutstrasse 78Address ZIP: 47533City: KleveCountry: GermanyPhone: +49 (0) 2821 804313Fax: +49 (0) 2821 804313Email: [email protected]: The use of new types of large and middle size vacuum batchfurnaces for the heat treatment of moulds and diesAuthors: Jamel Ben-Hamida, Matthias RinkTopic: A – Heat TreatmentPresentation type: Oral Figure 1: Inacceptable dies microstructure

temperature, quenching parameters with isothermal hold,if necessary, tempering parameters (number of temperingcycles depending on the achieved hardness, temperaturesand holding times).Additionally to the trials with the GM block trials withother parts are described in the presentation:One large 5,6 t diecasting die (1.2343) and two 230 kgforging dies (1.2343).The equipment specified by GMPT DC 9999-1 has to

meet various requirements:

Vacuum furnace with min. 10 bar nitrogen pressurebackfill, minimum quench rate 39°C/min, programmableprocess control with load thermocouples, digital data re-cording of the whole cycle, furnace certification accord-ing to MIL-H-6875.Based on those requirements two Ipsen Vacuum furnacesof different sizes have been used for the trials:

• SuperTurbo™ 77100 (useful dimensions WxLxH =1700x3000x1400 mm, max. gross weight of load =5000kg)

• Turbo�Treater M (600x900x600 mm, 800 kg).

3 RESULTS

The requirement stated in the GMPT Standard Specifica-tion DC 9999-1 in terms of furnace performances and interms of metallurgical could be achieved in both fur-naces IPSEN SuperTurbo™ 77100 and in Turbo�TreaterM.The diecasting die and the 230 kg forging dies showedexcellent results in hardness and microstructure.

ICHT & SETD 2008 HEAT TREATMENT

15

Figure 2: Test piece and Heat treating cycle as per GM POWER-TRAIN Standard Specification DC 9999-1

IPSEN SuperTurbo™ 77100 Turbo�Treater MDiecasting die GM 16" bloc Forging die GM 16" bloc

Material 1.2343 H13 (1.2344) 1.2343 H13 (1.2344)Weight 5600 kg 532 kg 460 kg 532 kg

Austenized at ~1020 °C 1043 °C 1.000 °C 1043 °CGas quenching at >9 bar >9 bar 7 bar 12 bar

Tempering ~595 °C – 585°C –Hardness 47 HRC – 49 HRC –

Figure 4: IPSEN Turbo�Treater M

Figure 3: IPSEN SuperTurbo™ 77100

HEAT TREATMENT

TWO-COMPONENT DIFFUSIVE STEEL SATURATION

Radoslav Ivanov*Department of Natural Science, Shoumen University "K. Preslavsky", Shoumen, Bulgaria

ABSTRACT

The present work is devoted to the research on diffusive saturation of steel with boron and copper, boron and nickel,and boron and cobalt. A subject of analysis have been the thickness of the obtained boride layers, their structure andcomposition, the level of cohesion of the layers, as well as the quantity of the alloying elements in them.

Keywords: steel, boriding, saturation, boride layer, thickness

1 INTRODUCTION

Boriding is a method for diffusive saturation of the sur-face of steel products with boron. As a result, one-phase(Fe�B) or two-phase (FeB+Fe�B) boride layer is formed.This layer is distinguished for the high level of solidity,stability to corrosion and high temperature, but also forthe great fragility. When alloying elements (Cu, Ni, Co,etc.) are put into the boride layer, the pace of its formingchanges significantly. Its composition, structure, cohe-sion to the metal base, and other properties change, too[1, 2].The aim of the present work aims the systemization ofour research on diffusive saturation of steel with boronand copper [3], boron and nickel [4], and boron and co-balt [5].

2 EXPERIMENTAL SETUP

Medium-carbon steel and alloyed instrumental steel havebeen borided in a powder boriding mixture with majorcomposition [97%(12% amorphous B+88% Al�O�)+3%Na�O.4BF�] [6], alloyed separately with Cu�O, Niand Co�O�. The quantity of the alloying supplement is inthe range of 0,0 to 5,0 weight %. The boriding is carried

in stainless steel container [7] out at 1080 K (810 °C)and lasts 5 hours.The borided samples are subjected to microstructuralanalysis, roentgenostructural analysis (RSA), and roent-genofluorescent analysis (RFA). The microstructuralanalysis and the measurement of the boride layers thick-ness (�) are carried out with a Neophot 2 microscope af-ter the black and white development (5% solution ofHNO� in C�H�OH) of metalographic grinds. The cohe-sion rate (s) of the layer to the steel base is determined asa positive square root of the deviations of the measuredvalues of layer thickness from its average values [8]. TheRSA is carried out on DRON-2 with a cobalt x-ray pipewith K�-rays, 30kV operating pressure, 20 µA current,and 1/2°/min ray speed. The contents of Cu, Ni, and Coon the surface of the boride layers is determined throughRFA. For this purpose samples are prepared by pressingpowder mixtures of Fe and Cu; Fe and Ni; Fe and Co. Asexcitement source is used 241 Am, radiating ã-rays on asilver padding. Carbon steel borided samples are submit-ted to a layer RFA, after layers as thick as 10-30 µm aretaken mechanically.

3 RESULTS AND DISCUSSIONS

The amount of Cu�O in the starting mixture is increased,the boride layer becomes smoothly thinner. There is anexception when samples are borided in a mixture with 2weight % Cu�O. The introduction of the same amountsof Ni or Co�O� in the starting mixture leads to reducingthe thickness of the boride layer to a greater extent.The thickness of the boride layers in carbon steel sam-ples in any case remains superior to the thickness of thesamples of alloyed steel. This is probably due to the tor-menting effect of the redistribution of chrome, carbon,molybdenum, etc., contained in the steel, on the borondiffusion.Cu alloying improves the cohesion rate which reaches itshighest level at 2 weight % Cu�O. Ni alloying leads to a

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Bled, 25–28 May 2008

* Name: RadoslavLast Name: IvanovTitle: Prof.Dr.Position: lecturerInstitution: Shoumen University"K. Preslavski"Address: 115 Universitetska Str.Address ZIP: 9712City: ShoumenCountry: BulgariaPhone: +359 054 830 495Fax: +359 054 830 371Email: [email protected]: TWO-COMPONENT DIFFUSIVE STEEL SATURATIONAuthors: Radoslav Iliev IvanovTopic: A – Heat TreatmentPresentation type: Poster

significant cohesion rate (18.8 µm) at 1% Ni in the start-ing mixture, then the cohesion rate varies from 9 to 13µm. Alloying the boride layer with Co does not improvethe cohesion rate.Figure 1 shows microstructures of boride layers formedon samples of carbon steel in powder mixtures with noalloying supplement (a), with supplement of 2.0%Cu�O(b), 3.0%Ni (c), and 2.0%Co�O� (d). It’s obvious that theprickly structure of the layer does not change, and thelayer becomes thick. For samples of alloyed steel thelayer is much thinner, the prickly structure is broken, andthe front of growth of the layer is smoothed.The results from RSA indicate that the obtained boridelayers are two-phase (FeB+Fe�B) with prevailinglow-boron (FeB) phase. No borides of Ni and Co havebeen found (Cu does not form borides). The alloying ele-ments are dissolved in the ferrous borides.The results from the RFA analysis shows that the amountof the introduced elements Cu, Ni, and Co is higher inthe boride layers formed on samples of the alloyed steel.

4 CONCLUSIONS

The boride layer obtained on the two types of steel istwo-phase (FeB+Fe�B), alloyed with Cu, Ni, or Co. Thelayer obtained on carbon steel keeps its prickly structureand becomes thicker. In the layer obtained on alloyedsteel, the prickly structure is broken and the front ofgrowth is smoothed.In conclusion, in order to raise the saturating ability ofthe starting boriding mixture and to improve the cohe-sion rate of the obtained boride layer to the steel base, itshould be recommended to be introduced in the mixtureup to 2.0% Cu�O as an alloying supplement. Supple-ments containy Ni and Co for such purposed is not ad-visable.

5 REFERENCES

[1] Lyahovitch L., Multicomponent diffusion backing, Minsk,Nauka i Tehnika, 1974

[2] Belskiy, E. etc., Chemical Heat Treatment of InstrumentMaterial, Minsk, Nauka i Tehnika, 1986

[3] Ivanov R., Scientific works, A. Kunchev Technical Uni-versity, Rousse, Vol. 35 (1994) 118-122

[4] Ivanov R. etc. Collection of reports Amtech’95, A.Kunchev Technical University, Rousse, 1995, 151-156

[5] Ivanov, R., M.Boneva, Scientific works, V. Levski MilitarySchool, V. Tirnovo, Vol. 39(1995) 89-94

[6] Ivanov, R., Composition for boriding of steel products, Au-thor’s certificate, R. Bulgaria, No 51, 823

[7] Ivanov, R., Mechanism for boriding of steel products, Au-thor’s certificate, R. Bulgaria, No 51, 308

[8] Matuschka, A. G., Kuenzel, Metall, 1985, 30, No 4,336-338


17

Figure 1: Microstructures (x100) of boride layers formed on carbonsteel in powder mixtures: a) with no alloying supplement; b) with sup-plement of 2.0%Cu�O; c) 3.0%Ni; d) 2.0%Co�O�.

HEAT TREATMENT

HEAT TREATMENT AND WELDING EFFECTS ONMECHANICAL PROPERTIES AND MICROSTRUCTUREEVOLUTION OF 2024 AND 7075 ALUMINIUM ALLOYS

Hakem Maamar*, Khatir Mohamed, Rabah Otmani Rafik,Fahssi Toufik, Debbache Nabil, Allou Djilali

Division de Mécanique et Métallurgie, Centre de Recherche Scientifique et Technique en Soudage et Contrôle.BP 64, Route de Dely Ibrahim, Chéraga, Algiers, ALGERIA

ABSTRACT

Aluminium alloys are sensitive to hot cracking during the welding operation both liquidation cracking in the heataffected zone (HAZ) and solidification cracking in the weld can occur.

The GTAWelding results of aluminium alloys 2024 T3 and 7075 T6 for 2 mm plate thickness with differentparameters of welding are presented in this paper.

Before welding, different alloys was heat treated at different temperature to follow the evolution of microstructureand mechanicals properties.

After welding, the strength of the materials in heat affected zone (HAZ) is reduced. This reduction on properties isdue to the different phenomenon that occurs during welding.

Keywords: heat treatment, aluminium alloys welding, hardness, precipitation, tensile strength, yield strength,microstructures

18


Bled, 25–28 May 2008

* Name: HAKEMLast Name: MaamarTitle: Mr.Position: Mechanical & Metallurgical DivisionInstitution: Resaech Center of Welding & Control. CSCAddress: Route de dely Ibrahim. BP 64 Cheraga.Address ZIP: 16000City: AlgiersCountry: ALGERIAPhone: +213 21 36 18 54Fax: +213 21 36 18 54Email: [email protected]: Heat Treatment and Welding Effects on MechanicalProperties and Microstructure Evolution of 2024 and 7075Aluminium AlloysAuthors: HAKEM. Maamar, KHATIR. Mohamed, RABAHOTMANI Rafik, FAHSSI. Toufik, DEBBACHE. Nabil, ALLOU.Djilali.Topic: A – Heat Treatment

HEAT TREATMENT

AFFECT OF VIBRATORY WELD CONDITIONING ONIMPACT TOUGHNESS OF WELD

Bogdan Puèko*Faculty of Mechanical Engineering, Maribor, Slovenia

ABSTRACT

Vibratory weld conditioning is a proceeding to achieve enhancement of weld metal microstructure. It could alsoaffect mechanical properties, level of residual stresses and deformation. In presented research work affect on impacttoughness of weld metal was performed. Four different types of single welds were made. Vibrated, tempered andcombination of both conditions were compared to as-welded condition. Results were compared and confirmed withmultipass weld impact toughness measurements. Vibration during welding benefits energy absorbed in impacttoughness test of weld metal and improves type of fracture.

1 SCOPE AND RESULTS

Purpose of research work in this article has been com-parison of impact toughness of different conditions ofwelds. As welded condition was primary compared toweld subjected to vibration during welding (vibratoryweld conditioning – VWC). To notice an influence ofheat of next pass when multipass welding is performed,we made two more samples. One of them was temperedto 500 °C for 20 min after welding; the other was sub-jected to VWC and tempered at 500 °C with vibration af-ter welding (vibratory stress relieving – VSR).Material researched was steel Niomol 490, welding pro-cess was SAW with flux cored wire. Single pass V weldswere made to machined slots. Nugget of weld was exam-ined to impact toughness with non-standard Charpy sam-ples. Some welds of different conditions were metallo-graphic and fractographic examined.Results express differences in impact toughness. Best re-sults were achieved with VWC samples. Influence ofheat impairs results, which could deter values achievedwith VWC in multipass welds. (Figure 1)

19


Bled, 25–28 May 2008

Figure 1: Impact toughness of welds

* Name: BogdanLast Name: PuèkoTitle: Dr.Position:Institution: Faculty of Mechanical EngineeringAddress: Smetanova 17Address ZIP: 2000City: MariborCountry: SloveniaPhone: (02) 220 76 75Fax:Email: [email protected]: AFFECT OF VIBRATORY WELD CONDITIONING ONIMPACT TOUGHNESS OF WELDAuthors: Puèko B.Topic: A – Heat TreatmentPresentation type: Poster Figure 2: Fracture surface of unvibrated and vibrated specimen

According to values and shape of instrumented Charpydiagrams, vibration during welding benefits impacttoughness. Fractographic examination of fractures, visu-

ally and with scanning electron microscope (SEM), re-veals differences in microstructure and therefore differ-ences in type of fracure (Figure 2).To clear up exclusive results of influence of vibrationand heat, we made two multipass welds with same baseand filler material. As-welded condition was comparedto VWC condition (Figure 3). Vibrated welds expresshigher impact toughness values.

2 CONCLUSIONS

According to results of impact testing, metallographicand fractographic research, there is positive influence ofvibration on welds. Vibration affects microstructure for-mation, type and energy of fracture. Although temperedsingle pass samples express lower toughness, multipasswelds also have higher impact energies when usingVWC.


20

Figure 3: Impact toughness of multipass welds

HEAT TREATMENT

THE EFFECT OF AGING PARAMETERS ONPROPERTIES OF MARAGING STEEL

Ivica Kladariæ, Dra�an Kozak, Dragomir KrumesUniversity of Osijek, Mechanical Engineering Faculty in Slavonski Brod, Croatia

ABSTRACT

In the paper the investigation of the aging parameters (temperature and time) effects on mechanical properties anddimensional changes of Maraging 15 10 5 steel is presented. Aging testings were carried out in dilatometeraccompanied by simultaneous registration of forthcoming alternations of size. The obtained results indicate tosignificant influence of aging temperature and aging time duration on achieved hardness values, as well as ondimensional changes, which is caused to diffusive character (diffusion of alloyed elements atoms fromNi-martensite matrix) of aging process.On the basis of carried out testing optimal aging temperature and aging time duration of Maraging 15 10 5 steel aredetermined.

Keywords: maraging steel, aging, mechanical properties, dimensional changes

1 INTRODUCTION

Maraging steels are delivered in solution annealed condi-tion and have relatively soft and ductile qualities whatmakes them suitable for exposure to work treatment. Therequired operational properties of these steels are ob-tained by precipitation hardening (aging), with result ofalmost doubling their hardness and tensile strength val-ues (compared to solution annealed condition).[1, 2]Besides high tensile and yield strength other advantagesand benefits of this sort of steel are to be emphasized:good plastic properties, good weld ability, resistance tobrittle fractures and stability at low and increased tem-peratures. The advantages are also displayed in theirconvenient heat treatment qualities. Due to the abovespecified advantages and their wide application thesesteels were submitted to further improvements and de-velopment. [2, 3]

2 EXPERIMENTAL WORK

The study included carrying out of experiments with thepurpose to investigate optimal parameters (temperatureand time) for aging of maraging steel with the following

composition: 0,010% C, 0,19% Cr, 14,33% Ni, 10,347%Co, 4,83% Mo, 0,006% V, 0,080% Al, 0,141% Cu,0,224% Ti, 0,004% Si and 0,008% Mn, which corre-sponds to designation of Maraging 15 10 5. The entiresamples were solution annealed and aged in Netszschelectronic dilatometer 402 EP. The use of dilatometerenables observation of ongoing dilatometric changes.The experiment was organised according to factorial ex-periment 3� as a variation of two factors (factor A – ag-ing temperature, factor B – aging time) on three levels(��=400 °C, ��=500 °C, ��=600 °C, t�=1h, t�=4h,t�=10h). With factorial experiment 3

�, the influence ofindividual factors and their interactions on mechanicalproperties and dimensional changes of Maraging 15 10 5steel was determined statistically. Besides variations ofall factor levels the three repetitions for the same combi-nation of factor level were conducted.After the completion of the heat treatment, each samplewas tested for hardness value by Vickers method withthe load of 9,81N (HV1), five measurements each, andafter that the average value was calculated.

2.1 Determination of the aging parameters effects onMaraging 15 10 5 steel

The results of variance analysis of measured hardnessvalues HV1 are presented in table 1. In table 2 the re-sults of variance analysis of measured dimensionalchanges (contraction) are presented. Analysis of variancewas carried out by the computer programme Statistica.The analysis of variance (table 1 and table 2) indicatesthe significant influence of factor A (aging temperature)on hardness values HV1 and dimensional changes afteraging. Factor B (aging time) and interaction betweenfactor A and factor B have lower influence on hardnessvalues and dimensional changes.

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Bled, 25–28 May 2008

* Name: IvicaLast Name: KladariæTitle: DrPosition:Institution: Mechanical Engineering Faculty in Slavonski BrodAddress: Trg Ivane Brluæ-Ma�uraniæ 2Address ZIP: 35000City: Slavonski BrodCountry: CroatiaPhone: 00 38535493453Fax: 00 38535446446Email: [email protected]: The effect of aging parameters on properties of maragingsteelAuthors: Ivica Kladariæ; Dra�an Kozak; Dragomir KrumesTopic: A - Heat Treatment

Figure 1 presents distribution of hardness values HV1and figure 2 presents distribution of dimensionalchanges (contraction) of maraging 15 10 5 steel depend-ing on factors levels.The analysis of figure 1 and figure 2 indicates the next:

– Hardness values HV1 and dimensional changes ofMaraging 15 10 5 steel are changed by variation ofaging temperature and aging time.

– The highest hardness values are achieved by agingtemperature of 500 °C.

– The increase of aging temperature above 500 °C andaging time above 4 hours significantly contributesthe contraction of maraging 15 10 5 steel.

3 CONCLUSION

On the basis of performed testing of optimal aging tem-perature and aging time duration for Maraging 15 10 5steel the following conclusions can be made:

– The obtained results indicate to essentially signifi-cant influence of aging temperature when comparedwith aging time duration on achieved hardness val-ues, as well as on shortening of steel samples, which

may be contributed to diffusive character of processof aging.

– The aging of Maraging 15 10 5 steel at 500 °C dur-ing 4 hours has a result optimal hardness value anddimensional change (contraction).

– During aging by above mentioned parameters hard-ness value of 510 HV1 and contraction of only 0,05% have been achieved.

– The obtained, relatively high hardness value with ac-companying dimensional changes (contraction) giveargument to conclude that this steel can be success-fully used up to maximal temperature of 500 °C.

4 REFERENCES

[1] G. Roberts, G. Krauss, and R. Kennedy, Tool Steels, ASMInternational, Materials Park, USA, 1998

[2] M. Novosel and D. Krumes, Posebni èelici, Strojarskifakultet u Slavonskom Brodu, 1998

[3] I. Kladariæ, F. Cajner and D. Krumes, Optimization of pa-rameters for aging of maraging steel, Proceedings –IFHTSE 2001, Dubrovnik, Croatia, 2001, 111-117


22

Figure 2: Distribution of dimensional changes of Maraging 15 10 5steel depending on factors levels

Figure 1: Distribution of hardness values HV1 of Maraging 15 10 5steel depending on factors levels

Table 1: Analysis of variance of HV1 values

Source of variation Degr. of freedom Sum of squares Mean of square Variance ratio v�Fisher criterion for

P=95%A 2 48185 24093 8340 3,554B 2 2763 1381 478 3,554

AB 4 19908 4977 1723 2,928Error 18 52 3

Table 2: Analysis of variance of dimensional changes

Source of variation Degr. of freedom Sum of squares Mean of square Variance ratio v�Fisher criterion for

P=95%A 2 15801,56 7900,78 599,22 3,554B 2 2214,89 1107,44 84 3,554

AB 4 2228,22 557,06 42,25 2,928Error 18 237,33 13,19

HEAT TREATMENT

AUSTEMPERING HEAT TREATMENT EFFECT ONMECHANICAL PROPERTIES OF AISI O1 STEEL

J. Vatavuk1, L.C.F. Canale2, George E. Totten3*1. Universidade Presbiteriana Mackenzie – Materials Engineering Department, Brazil

2. Depto. Eng. Materiais, Aeronáutica e Automobilística. EESC-USP, São Carlos, SP, Brasil3. Portland State Universty,Department of Mechanical and Materials Engineering, Portland, OR, USA

ABSTRACT

The paper describes results obtained with respect to mechanical properties, impact resistance of an AISI O1 steelalloy, after heat treatment by istothermal austempering, as well as comparison with the conventional quenching andtempering process. This study was conducted to understand the microstructural transformation kinetics with respectto time in the bainitic transformation region to verify the gradual increase of the bainite fraction until the totaltransformation. Microhardness and impact characterization was performed on the austempered and the quenchedand tempered samples to evaluate the interaction between microstructure and impact toughness at the same hardnessrange for both processes. The results of this work will be discussed in this paper.

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Bled, 25–28 May 2008

* George E. Totten, PhD, FASMPortland State UniversityDepartment of Mechanical and Materials Engineering514 N. 86th StreetSeattle, WA 98103Tel: 206-788-0188FAX: 815-461-7344E-Mail: [email protected]@getottenassociates.com

COOLING ASPECTS OF VACUUM FURNACES

R. Stein*, B. ZiegerSCHMETZ GmbH, Holzener Str. 39, 58708 Menden, Germany

ABSTRACT

The vacuum heat treatment with overpressure gas quenching is a fully accepted kind of heat treatment and firmlyestablished due to its versatile use. Due to the very different furnace versions the corresponding tools and workpieces can be heat treated according to the customers’ requirements. Even large forming tools can be successfullyquenched and tempered in vacuum furnaces according to the internationally well-known standards like NADCA.The accomplishing and measuring or the cooling process are shown in details.

Keywords: vacuum furnace, hot work steel, die casting dies, gas quenching, NADCA specification, martempering

1 TEMPERATURE DIFFERENCE IN THECOMPONENT – REASON OF DISTORTION

On principle the cycle of each heat treatment consists ofthe sections heating up, holding and cooling. When heat-ing up as well as during cooling temperature differencesoccur in the edges and in the core of the component.These temperature differences can not be avoided andare a reason for component stress which results into dis-tortion. In principle this component distortion can be re-duced considerably by slowly heating up and cooling.However, the microstructure, grain growth, hardenabilityof steel (quenching speed) and the economy demand afast run of the processes.

1.1 Heating up

Heating up in the vacuum chamber furnace is effected byconvection and radiation. In the lower temperature rangethe fast convective heating is made for a high tempera-ture uniformity in the load. In the upper temperatureranges the heat transfer is dominated by radiation. Onerequirement for the heating is the lowest temperature dif-ference possible within each component as well aswithin the whole load.

1.2 Cooling down

The cooling process of the heat treatment must fulfil therequirements like hardenability of steel, “quenching asfast as necessary and as slowly as possible”, uniformcooling of the load and keeping the temperature differ-ence in the component as low as possible.The realisation of these requirements leads to the maintarget: fully martensitic hardness structure with lowestdistortion. The quenching speed influences the measure-ment strength considerably. An ideal situation would bea cooling medium with exactly that speed which reachesthe sufficient hardness value. Because that would meanthe lowest risk for distortion and cracks. Quenchingpressure, quenching gas, cooling gas circulation speed,a.s.o. are parameters which make it possible to select thecooling speed in steps and to achieve absolutelyreproducable cycles and results. The constructive designof the furnace influences an uniform cooling decisively.The gas guidance and gas stream are important factorsregarding low distortion values. From all furnace con-cepts the principle of through streaming with directionreversal has succeeded at the market. The programmablecooling enables a defined, either-way vertical or horizon-tal cooling of the load.

1.3 Martempering

In order to minimise the thermal tension between com-ponent surface and -core a "marquenching simulation"("isothermal quenching") at a temperature higher thanmartensitic-start can be effected. The "marquenchingsimulation" lowers the distortion especially for big, geo-metrically complicated formed parts. For this"marquenching simulation" two thermocouples are fixedat one part of the load, one surface thermocouple andone core thermocouple.The load is cooled down from austenisation temperatureto "marquenching temperature", for example 400 °C.

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Bled, 25–28 May 2008

* Name: RonaldLast Name: SteinTitle: Mr.Position: Project EngineerInstitution: SCHMETZ GmbHAddress: Holzener Straße 39Address ZIP: 58708City: MendenCountry: GermanyPhone: +49 2373 686 189Fax: +49 2373 686 200Email: [email protected]: Cooling Aspects of Vacuum FurnacesAuthors: Ronald SteinTopic: A – Heat TreatmentPresentation type: Oral

The surface temperature goes down to this"marquenching temperature", but the core temperature isconsiderably higher at this moment, for example at 650°C. To achieve that the surface temperature is not goingdown on a deeper temperature, the cooling is interruptedand the heating is switched on. The core temperature isadapted slowly to the "marquenching / surface tempera-ture". As soon as the surface- / core adaptation has takenplace cooling down to unloading temperature can becontinued.

2 VACUUM-HEAT-TREATMENT OF HOT-WORKSTEEL ACCORDING TO THE STANDARD OFTHE AMERICAN AUTOMOTIVE INDUSTRY

For the heat treatment of die casting dies of hot-worksteel material 1.2343 – X38CrMoV51 – H11the Ameri-can automotive industry defines in their standards(NADCA-specification) the heat treatment process.Among other requirements the minimum quenchingspeed is measured from austenisation temperature to538°C in a depth of the workpiece (Ts) of 16 mm whichmust be of 30 °C/min. After that a martempering processof 425°C is demanded where the surface (Ts) must bekept between the close temperature range of 440°C and415°C until the difference between surface (Ts) and core(Tc) is smaller than 90°C. The proof must be deliveredwith a test component of 400 x 400 x 400 mm. At differ-ent companies the complete heat-treatment processes ina vacuum furnace with the useful space of 1000 x 1500 x1000 mm, payload 2500 kg, maximum quenching pres-sure 13 bar was realised.

2.1 quenching speed and marquenching at the speci-men 400 x 400 x 400 mm

At the specimen with the dimension 400 x 400 x 400mm, single weight 566 kgs the cooling rate fromaustenisation temperature 1000°C to 538°C at the depthof component of 16 mm measured in the middle of theside surface (Ts) with an overpressure gas quenching of13 bar nitrogen was more than 30°C/min. The demanded

temperature between surface (Ts) and core (Tc) duringthe martempering phase could be realised.

3 VACUUM FURNACE WITH SEPARATEQUENCHING CHAMBER

The conventional vacuum furnace with 10 baroverpressure has limits regarding the cooling intensity.Traditionally the demanded cooling speed of low alloyedmaterials is reached with oil- or salt bath processes. Oneof the many disadvantages of these techniques are thebad distortion results.The vacuum furnace with separate quenching chambersystem *2 PLUS* offers an increase of quenching speedscompared to the conventional vacuum furnace. The prin-ciple of this system is the spatial separation of the heat-ing- and cooling process. The processes run in singlechambers which are separated by a closing mechanismserving as thermal barrier. A fully automatic loading cartransports the load from one chamber to the other. Byseparating the heating- and cooling mechanism the cool-ing performance could be doubled compared to the con-ventional vacuum furnace.The specimen 400 x 400 x 400 mm was tested (accord-ing to NADCA-specification) regarding the maximumachievable quenching speed in the vacuum furnace withthe system *2 PLUS* with the useful space of 600 x 900x 600 mm. At this process with 10 bar nitrogenoverpressure quenching a maximum cooling speed fromaustenisation temperature to 538°C of more than60°C/min in the surface (at a depth of 16 mm) wasachieved.

4 SUMMARY

The modern furnace technology enables to do a low dis-

tortion vacuum heat treatment of several components

and steels.

Bigger components can be hardened with low distortionand a high profitability. The advantages of new develop-ments in vacuum heat-treatment with overpressure gasquenching can also be transferred to lower alloyed steels.


25

IN-SITU MONITORING OF VACUUM CARBURIZING1,2Mihael Bruncko*, 2A. C. Kneissl, 1Ivan Anzel

�University of Maribor, Slovenia�University of Leoben, Austria

ABSTRACT

The present paper describes development and testing of a new measurement method that enables non-destructiveand in-situ monitoring of vacuum carburizing process. The principle of the method is based on monitoring thecarbon diffusion during vacuum carburizing by the in-situ measurements of electrical resistance changes in thecarburizing sample. The results of experiments that were performed in a laboratory vacuum furnace under a lowpressure acetylene atmosphere (5 mbar) and at a temperature of 950°C are also depicted.

Keywords: vacuum carburizing, electrical resistance measurements, pure iron, acetylene

1. INTRODUCTION

Vacuum carburizing is a modern, very efficient and envi-ronmentally friendly process for case hardening of steels.The advantages of this technology compared to conven-tional gas carburizing process are a high reproducibilityand uniformity of heat treated samples, clean sample sur-face after treatment, the absence of internal and grainboundary oxidation, smaller shape change of treatedparts after quenching, easy carburizing of complexshapes such as thin or blind holes, low gas consumptionand gentle working environment for people and earth [1,2]. The carburizing is performed in vacuum furnaces un-der low pressure hydrocarbon gas atmosphere – usuallypure acetylene or mixtures with other gases [1-3]. Thedesired case depth and corresponding concentration pro-file of carbon are obtained by diffusion of carbon atomsfrom the furnace atmosphere into the steel matrix actu-ated by cyclical changing the saturated (active) and thediffusion (passive) stage of the process [1-3]. At the con-stant carburizing temperature the diffusion of carbon canbe supervised by controlling the duration of these twostages, where the optimal process parameters are usuallypre-determined with vacuum carburizing simulation pro-

grams [2, 3]. However, this approach has many short-comings needed to be overcome. For instance, the diffu-sion process during vacuum carburizing is very complexand therefore the desired depth and morphology of thecarburized zone throughout the steel matrix is not easy tocontrol. To avoid these problems and to take all advan-tages of this technology it is necessary to monitor bothstages of the process in-situ and continuously. The pres-ent paper describes one of the possible ways to over-come the above problems and to fulfill the requirementsof in-situ monitoring.

2 EXPERIMENTAL SETUP

We developed a nondestructive measurement methodthat enables identification and characterization of phe-nomena during vacuum carburizing of steels. The princi-ple of the method is based on monitoring the carbon dif-fusion during vacuum carburizing by in-situmeasurements of electrical resistance changes in the car-burizing sample. For this purpose the unique laboratorydevice was set up (Figure 1a). It is based on a specialmeasurement cell that enables in-situ electrical resistancemeasurements by four probe technique at high tempera-tures (up to 1100 °C) and in reactive atmosphere (Figure1b). Moreover, it is also feasible to transform electricalresistance changes into an instantaneous microstructureof carburized zone by a mathematical-physical algorithmwhich will be presented. This algorithm was based onthe assumption that the process of vacuum carburizingcan be treated as a sequence of the partial reactions pre-sented in the algorithm as parallel and/or serial time-de-pendent resistors in the electrical circuit.

3 RESULTS AND DISCUSSION

The vacuum carburizing experiments were performed ina laboratory vacuum furnace under a low pressure acety-

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Bled, 25–28 May 2008

* Name: MihaelLast Name: BrunckoTitle: Dr.Position: research assistantInstitution: University of Maribor, Facultiy of Mech. Eng.Address: Smetanova ulica 17Address ZIP: 2000City: MariborCountry: SloveniaPhone: 00386 2 220 7868Fax: 00386 2 220 7990Email: [email protected]: In-situ Monitoring of Vacuum CarburizingAuthors: M. Bruncko, A. C. Kneissl, I. AnzelTopic: A – Heat TreatmentPresentation type: Oral

lene atmosphere (5 mbar) at a temperature of 950 °C.With use of this measurement method the electrical resis-tance changes during vacuum carburizing of pure ironwere acquired and analyzed (Figure 2). The results ofmonitoring the kinetics of carburized zones obtained bythe novel measurement method were compared with ki-netics obtained by metallographic analysis of carburizedsamples (Figure 3). The comparison shows that ourmeasurement method gives enough qualitative and quan-titative information about the proceeding of the reactionsthat take place during vacuum carburizing in the mate-rial, to monitor and to control the process online andnon-destructive. Additionally, it is possible to: (i) distin-guish between saturated and diffusion stage of the pro-cess, (ii) optimize the duration of each stage and thethereby time-ratio between this two stages and (iii) pre-dict the progress of case depth into the matrix.

4 CONCLUSIONS

In this research a measurement method enabling in-situmonitoring of electrical resistance on the basis of thefour probe technique during vacuum carburizing under alow pressure acetylene atmosphere was designed andconstructed. The design of the measurement methodforms the foundation for the effective "in-situ" monitor-


27

Figure 1: Laboratory device (a) and measurement cell (b) for"in-situ" electrical resistance measurements

Figure 3: The progress and the morphology of carburized zone afteractive (a) and passive stage (b) of the process

Figure 2: In-situ measurement of electrical resistance changes duringvacuum carburizing of the pure iron at T=950°C

ing and characterization of the phenomena during vac-uum carburizing of steels.

5 REFERENCES

[1] I. Hitoshi, Advanced Acetylene Vacuum Carburizing,IHI Engineering Review, vol. 38 No. 2 (2005) 83-88

[2] S. Bruce, V. Cheetham, Low-Pressure Carburising Sys-tems: A Review of Current Technology, Proceedings –15�� IFHTSE and SMT20, Vienna, Austria, 2006

[3] P. Kula, R. Pietrasik, K. Dybowski, Vacuum carburiz-ing-process optimization, Journal of Mat. Proc. Tech.,Vol. 164-165 (2005) 876-881

28


HEAT TREATMENT OF CORROSION RESISTANT TOOLSTEELS FOR PLASTIC MOULDING

Reinhold Schneider1*, J. Perko2, G. Reithofer3� Upper Austrian Univ. of Applied Sciences – Wels

� Böhler Edelstahl GmbH & Co KG� Rübig Wärmebehandlung GmbH & Co KG

1 INTRODUCTION

Steels for the processing of synthetic materials are thefastest growing market within the tool steel sector. Ofthese, corrosion resistant tool steels are used for thoseapplications with the highest requirements not only oncorrosion resistance, but also on surface quality and inmany cases on toughness and wear resistance. Heat treat-ment parameters play a vital role in the adjustment ofthese properties in relation to each other and have to beselected carefully with regard to specific requirements.

2 MATERIALS OF INTEREST AND IMPORTANTHEAT TREATMENT PARAMETERS

Typical steels in use belong either to the group of13%-Cr or to the 17%-Cr steels and usually contain C orC+N contents sufficient to achieve hardness levels be-tween 50 and 60 HRC. Some examples are the standardgrades X42Cr13, X36CrMo17 and X90CrMoV18 or thenewer nitrogen alloyed grades M333 (~X30CrN14),M303 (~X30CrMoN14-1) and M340 (~X55CrMoN17-1)from Böhler Edelstahl.As these steels are usually heat treated in vacuum-fur-naces with gas quenching, there are three important pa-rameters to be considered:

– austenitising parameters (mainly temperature, butfor large workpieces also holding time)

– quenching rate (mainly based on quenching pressureand gas velocity)

– tempering temperatures (which have the largest im-pact on the steel’s properties)

3 REQUIRED AUSTENITIZING PARAMETERS

Austenitising is the necessary precondition for anyquenching process, but in the case of corrosion resistanttool steels, it requires special attention. Not only is thetransformation of the ferritic bcc lattice structure into fccaustenite of importance here, but also the formation of asolid solution containing C (and N), whereby a minimumcontent of 13% Cr also has to be dissolved and evenlydistributed within the austenite to achieve full corrosionresistance. This is especially important for the high car-bon grades which require a minimum austenitising tem-perature significantly above A��. Too high austenitisingtemperatures on the other side can cause different typesof heat treatment errors. Steels with lower carbon con-tents can suffer undesired grain growth, an effect that ismore strongly pronounced in the highest quality elec-tro-slag-remelted (ESR) or vacuum-arc-remelted (VAR)and nitrogen alloyed steel grades, which have the finestand most homogeneous carbide distribution in the softannealed state. This aspect has to be taken into specialaccount for large workpieces which require long holdingtimes at austenitising temperature for an even tempera-ture distribution in the whole workpiece.As for the high C and C+N alloyed grades, too highaustenitising temperatures lead to strongly increasedamounts of retained austenite and go hand in hand withhigher distortion and higher internal stresses. The usualprocess window for achieving optimum properties forthese types of steels is between 980 and 1030°C,whereas the ideal austenitising temperature is stronglydependent on the size of the tool. Especially for the C+Nalloyed grades the austenitising temperature should bedecreased with increasing wall thickness to avoid theformation of grain boundary precipitations caused by thelower cooling rates achieved during quenching.An additional aspect for this group of steels when usedin protective gas and vacuum furnaces is the nitrogenpressure applied during austenitisation. The main reasonfor this topic is the increased N solubility in the austenitedue to the high Cr content. While there exists the possi-

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Bled, 25–28 May 2008

* Name: ReinholdLast Name: SchneiderTitle: Prof.Dr.Position: Head of DepartmentInstitution: Upper Austrian Univ. of Applied Sciences – WelsAddress: Stelzhamerstrasse 23Address ZIP: 4600City: WelsCountry: AustriaPhone: 07242-72811-3910Fax: 07242-72811-93910Email: [email protected]: Heat Treatment of corrosion resistant tool steels for plasticmouldingAuthors: R. Schneider, J. Perko and G. ReithoferTopic: A – Heat TreatmentPresentation type: Oral

bility to enrich the surface with nitrogen for a nitrogencasehardening by operating the vacuum furnace under acontrolled (low) nitrogen pressure, no evidence ofde-nitrogenation for nitrogen alloyed steels with 0,1 –0,2 % N has been found.Finally, it should not be overlooked that heating toaustenitising temperature should be performed with oneor two pre-heating steps around the phase transformationtemperature to avoid internal stresses and correspondingdistortion.

4 OPTIMUM QUENCHING RATE

Traditional oil or salt-bath quenching usually provided avery rapid quenching rate, especially in the temperaturerange of 800 and 500 °C. With the introduction of gasquenching in vacuum furnaces, the main concern ini-tially was focused on the maximum workpiece dimen-sions that could be hardened to the core due to the lowerquenching rate. With the steady increase of maximumquenching pressures and optimised gas flow today nearlyall workpiece dimensions of these steels can be gasquenched, changing the focus towards internal stressesand distortion during quenching.However, it is widely regarded that those quenchingrates which produce the lowest internal stresses and dis-tortion just by achieving full hardness in the centre re-gions are indeed the optimum. In doing so, quenchingpressures (or velocities) are reduced to low levels (far)below the capabilities of the furnace. Unfortunately suchslow cooling rates do not correspond with the highesttoughness properties of the material, resulting in aworkpiece that is rather brittle. Therefore cooling rateshigher than the absolute minimum required to achievefull hardness are highly recommended in order toachieve the best material properties. Distortion can thanbe reduced by using helium as a quenching media, pro-viding a more uniform quenching.

5 SELECTION OF TEMPERING PARAMETERS

The largest effect on the material properties can beachieved by the selection of tempering parameters. Ma-terial properties such as hardness, toughness and corro-sion resistance, but also residual stresses depend widelyon the tempering temperature, and therefore applicationspecific combinations of these properties can be ad-justed.No tempering or very low (< 150 °C) tempering temper-atures are uncommon as they result in high internalstresses with high material brittleness. With increasedtemperatures toughness properties can be improved sig-nificantly with only limited loss in hardness (still above50 HRC) and almost no loss in corrosion resistance.When looking at toughness not as fracture toughness, butas impact toughness, which includes the energy neces-sary to create a crack, the degree of improvement, in-

cluding the toughness level in general, highly dependson the microstructure (fine and uniform or coarse) andsegregations, as well as on the cleanliness level. Thesefactors strongly depend on the steel’s composition (withadvantages for low C and N alloyed grades) and on theproduction method (standard ingot casting versus pre-mium quality electro-slag or vacuum-arc-remelted steelgrades). Depending on the grade, typical tempering tem-peratures for this combination of properties vary be-tween 200 and 400°C. Still it should be kept in mind,that this combination of properties does not only yieldgood toughness properties, but still bears high residualstresses and can therefore not be recommended for com-plicated workpieces, especially those with small radiusesand drastic changes of large and small dimensions. An-other option, often used for pre-hardened and temperedmaterial, is the use of tempering temperatures above550°C, leading to high toughness in combination withlow residual stresses. Unfortunately, hardness values areonly in the range of typically 30 – 40 HRC. Corrosionproperties strongly depend on the steel composition, withclear advantages shown for 17%-Cr, low C and for N al-loyed steels.In special cases the temperature gap between 400 and550°C but especially between 510 and 550°C, is used fortempering operations. Sometimes tempering in this re-gion is inevitable because of additional eroding or coat-ing processes applied to the workpiece afterwards, some-times this is performed to achieve a better compromisebetween deteriorating corrosion and toughness propertiesand reduced internal stresses for more complicatedworkpieces at high hardness levels. Thereby N alloyedlow-C grades exhibit a significantly better performance,as the loss in corrosion resistance is less pronounced andshifted towards higher temperatures.

6 CONCLUSIONS

To achieve the best properties for tools and dies madeout of martensitic corrosion resistant steels, several as-pects of heat treatment should be taken into careful con-sideration:

– Austenitising temperatures should be kept within avery small range (usually 980-1030 °C) for thewhole workpiece.

– The ideal austenitising temperature is strongly de-pending on the size of the tool. Especially for theC+N alloyed grades the austenitising temperatureshould be decreased with increasing wall thicknessto avoid the formation of grain boundary precipita-tions caused by the lower cooling rates achieved dur-ing quenching.

– Quenching in vacuum furnaces should be mostlyuniform and preferably at higher quenching rates toavoid the precipitation of grain-boundary carbides,especially for larger workpieces.


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– The selection of the tempering temperature highlydepends on the desired properties, and thereby itshould be kept in mind that good toughness proper-ties at medium temperatures (200-400 °C) usuallycorrespond with still high residual stresses, espe-cially in complicated workpieces. High Cr-low Cand N alloyed steels offer the possibility of increas-ing tempering temperatures up to 510-550 °C while

still keeping acceptable levels of corrosion andtoughness properties.

– High quality electro-slag or vacuum-arc-remeltedand N alloyed steels offer the potential for betterproperties, but only if the heat treatment is per-formed with the optimum combination of parame-ters.


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HEAT TREATMENT OF HOT WORK TOOL STEELS –SIZE MATTERS!

Georg Reithofer1*, T. Collins1, R. Schneider2� Rübig Wärmebehandlung GmbH & Co KG

� Upper Austrian Univ. of Applied Sciences – Wels

ABSTRACT

This article is intended to draw attention to the problems as well as some solutions manufactures face when usinghot work tool steels. Remarkable advances have been made in the performance of these steels in the last decade.Material properties have been improved with increasing cleanliness and homogeneity and a fuller understanding ofheat treatment and service conditions. Th

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Transcript of ICHT & SETD 2008 - IMTmit.imt.si/izvodi/mit086/SSHT_Bled2008.pdfTHE EFFECT OF SERVICE CONDITIONS ON...