FORGE Simulation Surface Hardening Techniques

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FEM SIMULATION OF SURFACE HARDENING TECH

- APPLICATIONS TO GEAR COMPONENTS -R.DUCLOUX 1 , S. ANDRIETTI 1 , J. BARLIER 1

1 TRANSVALOR SA - FRANCE 5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014


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INTRODUCTION

SURFACE HARDENING TECHNIQUES

CASE STUDY#1 : HEAT TREATMENT OF A BEVEL GEAR

CASE STUDY#2 : INDUCTION HARDENING OF A SPUR GEA

CONCLUSION & PERSPECTIVES

5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014

OUTLINE


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INTRODUCTION

Standard goals of forming process simulations

- Understand material flow : underfilling, folds & laps

- Determine optimum forming sequence : reduce design cycle

- Predict material properties : grain flow, microstructure

- Extend die life : stress analysis, wear, load,

Productivity, Quality, Innovation & Savings


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INTRODUCTION

Recent challenges

- Predict the in -use properties of the forgings

- Simulate the entire manufacturing process including all pre & forming operations (from initial heating to final heat treatment)

Todays presentation- Illustrate a wide range of heat treatment simulations- Application to surface hardening on forged components


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INTRODUCTION






OUTLINE


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SURFACE HARDENING TECHNIQUES Goal of surface (or case) hardening

- Increase wear resistance and surface hardness- Keep inner metal softer- Applicable to low carbon & alloy steel- Followed by heat treatment to get desired hardness- Typical parts are : pinion, camshaft, gear,

Among the most common techniques- Carburizing- Nitriding, other diffusion processes- Induction hardening

- Shot peening


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Application of surface hardening on gear componentsVery located and non-constant contact areaNeed to increase hardness on the surfaceNeed to maintain ductility in the core of the component

Source : http://science.howstuffworks.com/transport/engines-equipment/gear4.htm

Source : http://www.yourdictionary.com/bevel-gear

Source : http://science.how


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INTRODUCTION



CARBURIZING -> QUENCHING -> TEMPERING




OUTLINE


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CASE STUDY#1 : AUTOMOTIVE BEVEL GEAR

Complete forming sequence descriptionTwo warm forging stagesPiercing-Flash trimming, MachiningHeat treatment operations (carburizing-quenching-tempering)


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CASE STUDY#1 : PROCESS DATA Automotive bevel gear

Max outer diameter ~ 52 mm

Weight ~ 180 g Low carbon steel for carburizing (e.g. 20MnCr5)

Carburizing conditions Process : 2h40 at 850C Initial carbon rate in the part : 0.20% Atmosphere enriched in carbon : 0.8%

Quenching Oil bath : 20C during 2min HTC : 5500 W/C.m 2

Tempering To relieve internal stresses : 200C during 40min


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CASE STUDY#1 : CARBURIZING STAGE

Objectives of the carburizing stageIncrease of carbon concentration on surfaceIncrease quenchability for low carbon steel

0.20% carbon~

Lowquenchability

0.80% carbon~

Highquenchability

Isothermal diagram is shifted a

from 0.2


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CASE STUDY#1 : CARBURIZING RESULTS

Carbon concenafter carburizin

Carburizing


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CASE STUDY#1 : QUENCHING RESULTS

Phase distribution after oil quenching(martensite-bainite-pearlite-ferrite)

Residual stress d(1 st princip


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CASE STUDY#1 : PART DISTORTION

Distortion observed on the component after quenching due to plastic deformation(magnification x10)

Quenching


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CASE STUDY#1 : TEMPERING RESULTS

Effective stress relieving due to tempering- before (left) & after (right) -

Von Mises stress (MPa)

Tempering


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INTRODUCTION




LOCAL HEATING BY INDUCTION -> QUENCHING



OUTLINE


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CASE STUDY#2 : STRAIGHT-CUT OR SPUR G

Typical in -use conditions with loading / unloading sequence

Alternative compression vs. tension mode at the root of the teeth


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CASE STUDY#2 : STRAIGHT-CUT OR SPUR G

How to increase the resistance to fatigue loadingfor contact fatigue : increase local hardnessfor bending fatigue : increase compressive residual stressObjective : delay cracks propagation

Mater

Resist

Yield UltimaElong

Pressu

Red =Blue


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CASE STUDY#2 : HEAT TREATEMENT SEQU

Heating (induction) TemperingQuenching (water jets)


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INDUCTION HEATING : FEM SOLVERS

Heating

Electro magnetic solver FORGE SolverHeating source

Temperature

Air

Inductor

WorkpieceOnly workpiece


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INDUCTION HEATING : GLOBAL MESHING T

Heating

Generation of a unique global FEM mesh

Inductor & Part : import from CAD

Air : defined via box or cylindrical area around the inductor

The global mesh gathers all entities (air+inductor+part)


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CASE STUDY#2 : PROCESS DATA

Heating (induction)

Quenching (water jets)

Spur gear Diameter : 100mm (outer) 84mm (inner) Thickness : 10mm Alloy steel : 34CrNiMo6 (DIN 1.6582 AISI 9480)

Induction heating Current intensity : 4000 A Current frequency : from 5KHz to 20 KHz

Heating time : from 2 to 10 sec

Quenching HTC : 2600 W/C.m 2

Media temperature : room temperature Time : 15min


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CASE STUDY#2 : RESULTS

Heating (induction)

Heat power (W/m3) Magnetic field (A/m


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Heating (induction)

Temperature (deg C) Austenite rate


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Heating (induction)

Low frequency High frequencyHeating time is longer Heating time is shorter

Preferential heating zone: tooth base Preferential heating zone: tooth tip

= 4000 Af = 5 kHzHeating time = 10 sec

Austenite distribution Austenite distribution

Dual frequency ?


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CASE STUDY#2 : RESULTS Heating (induction) Quenching (water jets)

Martensite rateTemperature (deg C)


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CASE STUDY#2 : RESULTS Heating (induction) Quenching (water jets)

Martensite distribution - Frequency = 20000 Hz

Depth

-400

-300

-200

-100

0

100

200

300

0 0,5 1 1,5

Residual stresses (Mpa)

0

100

200

300

400

500

600

700

800

0 0,5 1 1,5

Hardness (HV)

Final material properties by the qu


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INTRODUCTION






OUTLINE


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Process simulation is the key-solution :

- Simulate the complete manufacturing process.- Associate Heat treatment & Forming operations.- Predict the final in-use properties of component.

State of the art surface hardening techniques can be simulated

- Carburizing + Quenching + Tempering.- Impact of carbon rate on IT diagram for martensitic transforma- Induction hardening (heating + quenching).- Right compromise for process parameters.


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CONCLUSION & PERSPECTIVES Extensive capabilities in FORGE NxT :

- Forming process & heat treatment simulations- Heat treatment capabilities : austenitisation, hydrogen diffusion

carburizing, quenching, tempering, - Unique electro-magnetic solver for induction heating, hardenin

heat treating,

Keep increasing our competitive advantages with :- Enhanced phase transformation models- Complementary surface treatment : nitriding, carbonitriding- Precipitate prediction incl. coupling with strain & stress


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THANK YOU

FOR YOUR ATTENTION ADDRESS:

694, av du Dr. Maurice DonatParc de Haute Technologie

06255 Mougins cedexFrance

CONTACT:+33 (0)4 9292 4200 +33 (0)4 9292 4201

[email protected]://www.transvalor.com/


FORGE Simulation Surface Hardening Techniques

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