ANSI-AGMA 2004-B89-Gear Materials and Heat Treatment Manual

8/18/2019 ANSI-AGMA 2004-B89-Gear Materials and Heat Treatment Manual

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ANSI/AGMA 2004---B89

(Revisionof AGMA 240.01)

J anuary1989

Reaffirmed October 1995

AMERICAN NATIONAL STANDARD

Gear MaterialsandHeat TreatmentManual


2/79

G ear Ma terials and Hea t Treatment Manual

2004---B 89iiANSI/AG MA

Gear MaterialsAndHeatTreatmentManual

AGMA 2004---B89

(Revisionof AGMA 240.01)

[Tables or ot her self---supporting sections may be q uote d or extract ed in their entiret y. C redit lines should

rea d: E xtracte d fro m AG MA 2004---B 89, Gear M aterials and H eat Treatment M anual, with the permission of thepublisher, t he American G ear Ma nufacturers Association, 1500 King Street, Suite 201, Alexandria , Virginia

22314.]

AG MA Sta ndards a re subject to consta nt improvement, revision or withdra wal a s dicta ted by experience.

Any person who refers to a n AG MA Technical Publicat ion should be sure that the publication is the latest avail-

able from the Association on the subject matter.

ABSTRACT

The Gear Materials and H eat Treatment M anual provides information pertaining to engineering materials

and materia l treat ments used in gear manufa cture. Topics included a re definitions, selection guidelines, hea t

treat ment, qua lity control, life considerations and a bibliography. The materia l selection includes ferrous, non-

ferrous and nonmetallic materials. Wrought, cast, and fabricated gear blanks are considered. The heat treat-

ment section includes data on through hardened, flame hardened, induction hardened, carburized, carboni-

trided, and nitrided gears. Quenching, distortion, and shot peeninga re discussed. Qua lity control is discussed as

related t o gea r blanks, process control, a nd meta llurgical testing on the final products.

Copyright E , 1989

Rea ffirmed O ctober 1995

American G ear Ma nufacturers Association

1500 King Stree t, Suite 201

Alexan dria , Virginia 22314

February 1989

ISB N: 1---55589---524---7


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2004---B 89iiiANSI/AG MA

FOREWORD

[The foreword, foo tnotes, and a ppendices, if any, are provided for informat ional purposeso nly and should

not be construed as pa rt o f AG MA St an da rd 2004---B 89 (Formerly 240.01), G ear M aterials and H eat Treatment

Manual .]

The Standa rd provides a broad range of information on gear mat erials and their heat treatment. It is in-tended to a ssist the designer, processengineer, manufacturer and hea t treat er in the selection and processing of

materialsfor gearing. D ata contained herein representsa consensusfrom metallurgical representatives of mem-

ber companies of AG MA.

This Standa rd replaces AG MA 240.01, October 1972. The f irst draf t of AG MA 240.01, Gear Materials

Manual , was prepared in October 1966. It wa s approved by the AG MA membership in March 1972. Reprinting

of AG MA 240.01for distribution was discontinued in 1982 because it ha d been decided in 1979 by the Met allur-

gy and Ma teria ls C ommitt ee to revise its for mat . The initia l draft of AG MA 2004---B 89 (for merly 240.01) was

completed in April, 1983. Work continued on t he Sta ndard with numerous additiona l revised draft s within the

Metallurgy and Ma terials Committee until it was balloted in 1988. It was completed and approved by the

AG MA Technical D ivision Executive Co mmittee in September 1988 and o n Ja nuary 23, 1989 it was approved as

an American National Standard.

Suggestions for t he improvement of this standard will be welcome. They should be sent to the American

G ea r Ma nufa cturers Associatio n, 1500 King Stree t, Suite 201, Alexan dria , Virginia 22314.


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2004---B 89ivANSI/AG MA

PERSONNEL of theAGMA Committeefor MetallurgyAndMaterials

Cha irman: L. E. Arnold (Xtek, Inc.)

Vice C hairman: G . J . Wiskow (Falk)

ACTIVE MEMBERS

M. Abney (Fairfield Manufacturing)

R . J . Andreini (Earle M. J orgensen)

E. S. B erndt (C and M of Indiana)

J . B onnet (WesTech)

N. K. Burrell (Metal Improvement Co. Inc.)

R . J. C unningham (B oeing)

P. W. E arly, J r. (G leason)

A. G iammarise (G eneral Electric)

J. P. H orvath (G . M . C hevrolet --- M uncie)

J. B ruce Kelly (G eneral Motors)

D . R . M cVittie (The G ea r Works --- Sea ttle)

N. P. M ilano (Regal Beloit C orporation)

A. G . M ilburn (The G ea r Works --- Sea ttle)

P. Rivart (CLECIM)

R . H. Shapiro (Arrow G ear)

W. L. Shoulders (Reliance E lectric) (D eceased)

M. Starozhitsky (Outboard Ma rine)

A. A. Swiglo (IPSEN)

S. Tipton (C at erpillar)

D. Vukovich (Eaton)

L. L . Witte (G eneral Motors)

ASSOCIATE MEMBERS

T. B ergq uist (Western G ea r)

J. D . B lack (General Motors)

E. R. Ca rrigan (Emerson E lectric)

P. E. Cary (Metal Finishing)

H. B . G ayley (IMO D elaval)

J. F. Craig (Cummins Engine)

T. C . G lew (Prager)

D . K. G uttshall (IMO D elaval)

W. H . H eller (Pee rless Winsmith)

D. L. Hillman (Westinghouse, Air Brake)

B. A. Hoffmann (Dresser)

L. D . H ouck (Ma ck Trucks)

A. J. Lemanski (Sikorsky)

R. L. Leslie (SPECO Corporation)

B. L. Mumford (Alten Foundry)

G . E . Olson (Cleveland)

J. R . Partridge (Lufkin)

E. M . R ickt (Auburn G ear)

H. I. Sanderow (Supermet)

R . L. Schwettman (Xtek, Inc.)

L. J . Smith (Invincible G ear)

Y . Sueyoshi (Tsubakimoto C ha in)

M. Tana ka (Nippon G ear)

R. E. Vaglia (Farrel Connecticut)

T. L . Winterro wd (C ummins Engine)


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2004---B 89vANSI/AG MA

Tableof Contents

Section Title Page

1. Scope 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2. References a nd Informa tion 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2.1 References 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.2 Informa tion Sources 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3. D efinitions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4. Ma teria ls Selection G uidelines 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.1 Mecha nica l Properties 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.2 G ra de a nd H ea t Trea tment 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.3 C lea nliness 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.4 D imensiona l Sta bility 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.5 C ost a nd Ava ila bility 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.6 H a rdena bility 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.7 Ma china bility 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.8 Ferrous G ea ring 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.9 Select io n C riteria f or Wrought , C a st , o r Fa brica ted St eel G e aring 19. . . . . . . . . . . .

4.10 C opper B a se G ea ring 19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.11 Other Non ---Ferrous Ma teria ls 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4.12 Non ---Meta llic Ma teria ls 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5. H ea t Trea tment 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.1 Through H a rdening Processes 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.2 Fla me a nd Induction H a rdening 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.3 C a rburizing 34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.4 C a rbonitriding 38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.5 Nitriding 39. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.6 Other H ea t Trea tments 41. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5.7 Quenching 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.8 D istortion 42. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.9 Shot Peening 47. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5.10 Residua l Stress E ffects 51. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6. Meta llurgica l Qua lity C ontrol 52. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.1 Incoming Ma teria l Qua lity C ontrol 52. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.2 Incoming Ma teria l H a rdness Tests 52. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.3 Incoming Ma teria l Mecha nica l Tests 53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.4 H ea t Treat Process C ontrol 53. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.5 Pa rt C ha ra cteristics 55. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.6 Meta llur gica l, Mecha nica l a nd N on---D est ruct ive Test s a nd Inspect ions 56. . . . . . . .6.7 Microstructure 61. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6.8 Mecha nica l Property Test B a r C onsidera tions 63. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

B ibliogra phy 64. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .


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2004---B 89viANSI/AG MA

Tableof Contents

Section Title Page

Appendices

Appendix A P la stic G ea r Ma teria ls 65. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Appendix B Approximate Maximum Controlling Section Size Considerations forThrough H a rdened G ea ring 67. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Appendix C C a se H a rdena bility of C a rburizing Steels 69. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Appendix D Service Life C onsidera tions 70. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Ta bles

Ta ble 4---1 Typica l G ea r Ma teria ls --- Wrought Steel 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 4---2 Typical Brinell H ardness Ranges and Strengths for Annealed,

Norma lized & Tempered Steel G ea ring 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 4---3 Typical Brinell Ha rdness Ra nges and Strengths for Q uenched

a nd Tempered Steel G ea ring 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Ta ble 4---4 Ma china bility of C ommon G ea r Ma teria ls 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 4---5 Mecha nical Pro perty Req uirements --- Cold Dra wn, Stress Relieved

Steel B ars (Specia l C old D ra wn, H igh Tensile) 11. . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 4---6 Typical Chemical Analyses for Though Hardened Cast Steel G ears 14. . . . . . . . . . .

Ta ble 4---7 Tensile P ro pert ies o f Thro ugh H a rde ned C a st St eel G e a rs 14. . . . . . . . . . . . . . . . . . .

Table 4---8 Minimum Ha rdness and Tensile Strength Requirements for G ray Ca st Iron 16. . .

Ta ble 4---9 Mecha nica l Properties of D uctile Iron 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Ta ble 4---10 C hemica l Ana lyses of Wrought B ronze Alloys 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 4---11 Typical Mechanical Properties of Wrought Bronze Alloy Rod and B ar 22. . . . . . . . .

Ta ble 4---12 C hemica l Ana lyses of C a st B ronze Alloys 23. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Ta ble 4---13 Mecha nica l Properties of C a st B ronze Alloys 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Ta ble 5---1 Test B ar Size for C ore H a rdness D etermina tion 35. . . . . . . . . . . . . . . . . . . . . . . . . . .

Table 5---2 Typical Effective Case Depth Specifications for Carburized G earing 38. . . . . . . . . .Ta b le 5 ---3 A pproxima t e Minim um Core Ha r dness of Ca r burized G ea r Teet h 39. . . . . . . . . . . .

Ta b le 5 ---4 A pproxima t e Minimum S ur fa ce Ha r dness --- N it rid ed S teels 41. . . . . . . . . . . . . . . . .

Ta ble 5---5 C ommonly U sed Q uencha nts f or Ferro us G e a r M at eria ls 43. . . . . . . . . . . . . . . . . . .

Ta ble 5---6 Typica l Shot Size a nd Intensity for Shot Peening 50. . . . . . . . . . . . . . . . . . . . . . . . . . .


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2004---B 89viiANSI/AG MA

Tableof Contents

Section Title Page

Figures

Fig 4---1 Typica l D esign of C a st Steel G ea rs 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Fig 4---2 D irectiona lity of Forging Properties 20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Fig 5---1 Variation in Ha rdening Patterns Obtainable on

G ea r Teeth by Fla me H a rdening 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Fig 5---2 Variations in Ha rdening Patterns Obtainable on

G ea r Teeth by Induction H a rdening 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Fig 5---3 Recommended Maximum Surface Ha rdness and Effective Ca se D epth

Hardness Versus Percent Carbon for Flame and Induction Hardening 33. . . . . . .

F ig 5---4 G e nera l D e sign G u id elines f or B la nks f or C a rburized G e a ring 45. . . . . . . . . . . . . . .

Fig 5---5 Typica l D ist ortio n C ha ra ct erist ics of C a rburized G e a ring 46. . . . . . . . . . . . . . . . . . . .

Fig 5---6 Shot Peening Intensity C ontrol 48. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

F ig 5--- 7 R esid ua l S tre ss by P ee nin g 1045 St ee l a t 62 H R C w it h 330 Sh ot 49. . . . . . . . . . . . . .

F ig 5--- 8 D e pt h o f C o mpr essive St re ss Ve rsus Alme n I nt en sit y f or S te el 50. . . . . . . . . . . . . . .

Fig 6---1 C ircula r (H ea d Shot) Ma gnetic Pa rticle Inspection 58. . . . . . . . . . . . . . . . . . . . . . . . .

Fig 6---2 C oil Shot Ma gnetic Pa rticle Inspection 59. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Fig 6---3 U ltra sonic Inspection Oscilloscope Screen 61. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

F ig 6 ---4 D i st a nce---Amplit ud e Reference L ine for Ul tr a soni c Inspect ion 62. . . . . . . . . . . . . .


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2004---B 891ANSI/AG MA

1. Scope

This Manual wa s developed t o provide basic in-

formation and recommend sources of additional in-

formation pertaining to gear materials, their treat-

ments, and other considerations related to the

manufacture and use of gearing.

Metallurgical aspects of gearing as related to rat-

ing (a llowable s ac a nd s at values) are not included,

but, are covered in AG MA rating standa rds.

2. ReferencesandInformation

2.1References.

Abbreviations a re used in the references to spe-

cific documents in this Stand ard. The a bbreviations

include: AGMA, American G ear Ma nufacturers

Association; ASNT, American Society of Nonde-

struct ive Testing; ASTM, Ame rica n Society fo r Test-

ing Materials; SAE, Society of Automotive Engi-

neers.

The following documents contain provisions

which, through reference in this Stand ard, constitute

provisions of this document. At the time of publica-

tion, the editions were valid. All publicationsa re sub-

ject to revision, and the userso f this Stand ard a re en-

couraged to investigate the possibility of applying the

most recent editions of the publicat ions listed.

AG MA 141.01---1984, Plastics Gearing ---

Molded, Machined, And Other Methods, A Report on

theState of the Art AG MA 2001---B 88, Fundamental Rating Factors

and Calculation M ethodsfor InvoluteSpur and H elical

G ear Teeth

AG MA 6033---A88, Standard for M arine Propul-

sion Gear Units, Part 1 Materials

ANSI /AG MA 6034---A88, Practicefor Single and

D ouble Reduction Cylindri cal --- Worm and H elical ---

Worm Speed Reducers

ASNT---TC ---1A (J une 80), Recomm ended Prac-

tice by American So ciety fo r Non destructive Testing

ASTM A48 ---83, Specification for Gray I ron Cast- ings

ASTM A148---84, Steel Castin gs, H igh

Strength, for Struct ural Purposes

ASTM A220---76, Specification for Pearlitic Mal-

leable Ir on Castings

ASTM A255---67, M ethod for E nd --- Qu ench Test

for H ardenability of Steel

ASTM A290---82, Carbon and Alloy Steel Forg-

ings for Rings for Reduction G ears

ASTM A310---77, Methods and Definitions for

M echanical Testing of Steel Products

ASTM A311---79, Specifi cation for StressRelieved

Cold D rawn Carbon Steel B ars Subject to M echanical

Property Requir ements

ASTM A356---84, H eavy--- Walled Carbon, L ow

Al loy, and Stain less Steel Castin gs for Steam Turbin es

ASTM A370---77, Methods and Definitions for

M echanical Testing of Steel Products

ASTM 388---80, Recommended Practice for Ul-

trasonic E xaminati on of H eavy Steel Forgings

ASTM A400---69(1982), Recommended Practice

for Selection of Steel Bar Compositions According to

Section

ASTM A534---87, Standard Specification for Car-

burizing Steels for An ti --- Friction Bearings

ASTM A535---85, Standard Specifi cation for Spe-

cial --- Quali ty Ball and Roll er B earing Steel

ASTM A536---80, Specification for Ductile Iron

Castings

ASTM A833---84, Indentation H ardnessof M etal-

lic M aterials by Comparison H ardness Testers

ASTM A609---83, Specification for Steel Castings,

Carbon and L ow Alloy Ultrasonic Examinations

Thereof

ASTM B 427---82, Specification for Gear Bronze

Al loy Castings ASTM B 505---84, Specifi cation for Copper--- Base

All oy Continuous Castings

ASTM E8---83, M ethods of Tension Testin g of M e-

tallic M aterials

ASTM E10---78, Test M ethod for Bri nell H ardness

of M etallic M aterials

ASTM E18---79, Test M ethods for Rockwell H ard-

ness and Rockwell Superficial H ardness of M etalli c

Materials

ASTM E54---80, M ethod for Chemical A nalysis of

Special Brasses and Bron zes ASTM E112---84, M ethodsfor D eterminin g Aver-

age G rain Size

SAE J 434---J une 86, Automotive Ductile (Nodu-

lar) Iron Castings

SAE J 461---Se pt 81, Wrought and Cast Copper

Alloys

SAE J 462---S ept 81, Cast Copper Alloys


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SAE J 463---S ept 81, Wrought Copper and Copper

Alloys

SAE J 808a ---SAE H S 84, Manual on Shot Peen-

in g

MIL ---S ---13165 B (31 D ec 66 Amendment 2---25

June 79), Shot Peenin g of M etal Parts MIL ---STD ---271F, Requirements for Non destruc-

tive Testing M ethods

ASTM E 709---80, Magnetic Particle Examination

ASTM E125, Reference Photographs for Magnet-

ic Particle In dications on Ferrous Castings

ASTM E 186---8, Standard Reference Radio-

graphs for Heavy Walled (2 to 4 1/2 inch)(51 to 114

mm) Steel Castings


graphs for H eavy Walled (4 1/2 to 12 inch) (114 to 305

mm) Steel Castings

ASTM E 399---83, Test M ethod for Pl ain --- Strain

Fracture Toughness of Metallic Materials


graphs for Steel Castings U p to 2 inch (51 mm) in

Thickness

ANSI /SAE AMS 2300 F, Magnetic Particle In-

spection , Premi um Ai rcraft --- Qu ali ty Steel Cleanlin ess

ANSI/SAE AMS 3201 G , Magnetic Particle In-

spection , A ircr aft --- Qu ali ty Steel C leanli ness

2.2Information Sources.Design of gears is concerned with the selection

of materials and metallurgical processing. This

Manual cannot substitute for metallurgical exper-

tise, but is intended t o be a basic tool to a ssist in the

selection a nd meta llurgical processing of gear ma te-

rials. The material information and metallurgical

processes conta ined herein a re based o n established

data and practices which can be found in the ap-

propriate publications. It is necessary that the de-

signer use a source of metallurgical knowledge of ma-

terials a nd processing.

Material specifications are issued by agencies,

including the government, large industrial users, an d

technical societies, some of whom a re:

ASM International

ASM Metals Ha ndbooks

ASM Hea t Treate rs G uide

ASM Metals Reference B ook

ASM Standard

American So ciety for Testing and Ma terials

ASTM Standards

Society of Automotive E ngineers, I nc.

SAE Handbook

American Iron and Steel Institute

AISI Steel Products Ma nuals

American National Standards Institute

ANSI Sta ndards

Naval Publications and Forms Center

Military Standards and Specifications

Metal Powder Industries Federation

MPIF Standard 35

Copper Development Association

CDA Data books

Iron Castings Society

G ray and D uctile Iron Ca stings Ha ndbook

Steel Founders’ Society

Steel Castings Handbook

3. Definitions

Annealing --- Full. Full annealing consists of

hea ting steel or o ther f errous alloys to 1475---1650 _ F(802---899 _ C) and furnace cooling to a prescribedtemperature, generally below 600 _ F (316 _ C). Thistreatment forms coarse lamellar pearlite, the best

microstructure f or ma chinability of low a nd medium

carbon steels. Unless otherwise stated, annealing is

assumed to mean full annealing.

Annealing --- Spheroidizing. Spheroidize

annealing is a process of heating and cooling steeltha t produces a globular carbide in a ferritic mat rix.

This heat t reatment results in the best machinability

for high carbon (0.60percent carbon or higher) and

alloy steels.

Austempering. Austempering is a heat treat pro-

cess consisting of quenching a ferrous alloy (steel or

ductile iron) from a temperature above the trans-

format ion range in a mediumha ving a rate of cooling

sufficiently high t o prevent high te mperature tra ns-

formation products, and maintaining the alloy tem-

perature within the bainitic range until desiredt rans-

formation is obtained. The bainitic transformationrange is below the pearliticra nge, but above the mar-

tensitic range. Austempering is applied to steels and,

more recently in the development stage for ductile

iron gearing (refer to 4.8.4.3).

Austenite. Austenite in ferrous alloys is a micro-

structural pha se consisting of a solid solution o f car-

bon and alloying elements in fa ce---centered cubic

crystal structured iron.


11/79



AustenitizingTemperature.The temperat ure at

which ferrous alloys undergo a complete microstruc-

tural phase transformation to austenite.

Bainite. Bainite is a microstructural phase re-

sulting from the transformation of austenite, and

consists of an aggregate of ferrite a nd iron carbide.

Its appearance is feathery if formed in the upper por-tion of the bainite transformation range, and acicular

if formed in the lower portion.

Carbon. C arbon is the principal ha rdening ele-

ment in steel, and it’s amount determines the maxi-

mum hardness obtainable. G enerally as carbon is in-

creased, t ensile strength a nd wear resistance in-

crease; however, ductility a nd welda bility decrease.

Carbonitriding. A modified form of gas carbu-

rizing, in which steel (typically plain carbon and very

low alloy) is heated between 1450---1650 _ F

(788---899 _ C) in a n ammonia enriched carburizingat mosphere. This results in simultaneous absorptionof carbon and nitrogen, which results in the forma-

tion of complex nitrides in a high carbon case.

Carburizing---Gas. G as carburizing consists of

heating a nd holding low carbon or a lloy steel (less

than 0.30 percent carbon) at 1650---1800 _ F(899---982 _ C) in a controlled carbonaceous atmo-sphere, which results in the diffusion of carbon into

the part (0.70---1.00 percent carbo n is t ypically ob-

ta ined a t the surface). Temperatures a bove 1800 _ F(982 _ C) may be ultilized in specialized equipment

such as vacuum carburizers. After carburizing, partsa re e ither cooled t o 1475---1550 _ F (802---843 _ C ) a n dheld at this temperature to stabilize and then direct

q ue nch ed ; o r slo w co ole d a nd r ehe a te d t o

1475---1550 _ F (802 ---843 _ C) a nd quenched.

Case Depth of Carburized Components. The

case depth for carburized gearing may be defined in

several ways including effective case depth, etched

case depth, total case depth, and depth to 0.40 per-

cent carbon. The carburized case depth referred to in

this Manua l will be effective case depth. Ca rburized

case depth terms are defined as follows:

(1) Effective case depth. The effective case

depth is the hardened depth to HRC 50 at 0.5 tooth

height a nd mid face width, normal to the tooth sur-

face.

(2) Et ched case depth. Et ched case depth is de-

termined by etching a sample cross---section with ni-

tric acid, a nd measuring the depth of the da rkened

area. The etched case a pproximates the effective

case. Ha rdness survey is preferred for contra l pur-

poses.

(3) Tota l case depth. The total case depth is the

depth to which the carbon level of the case has de-

creased to the carbon level of the ba se material. This

is approximat ely 1.5 times the effective case dept h.

(4) C ase depth to 0.40 percent carbon. Ef fectivecase depth is less frequently referred to a s the depth

to 0.40 percent carbo n. This depth may be mea sured

by analyzing the carbon content or estimating based

on microstructure. E stimating based on microstruc-

ture ignores the hardenability of the base material

and isnot as accurate a measurement as directly ana-

lyzing the carbo n level. There is poor correla tion be-

tween microstructure readings and material strength

gradients using this method.

CaseDepthofFlameorInductionHardenCom-

ponents. This is defined as the depth at which the

hardness is10H RC pointsbelow the minimumspeci-

fied surface ha rdness.

CaseDepth of Nitrided Components. Nitrided

case depth is defined as the depth a t which the hard-

ness is equivalent to 105 percent of the measured

core hardness. The case depth is determined by a mi-

crohardness tester and measured normalto theto oth

surface at 0.5 tooth height and mid face width.

CaseHardness. C ase H ard ness is the micro ---

hardness measured perpendicular to the tooth sur-

fa ce a t a depth of 0.002 to 0.004 inches (0.05 to 0.10

mm) at 0.5 tooth height and mid face width.

Cementite. Cementite is a hard microstructure

phase otherwise known as iron carbide (Fe 3C) andcharacterized by a n ort horhombic crysta l structure.

Combined Carbon. The amount of carbon in

steelor cast iron that ispresent in other than elemen-

tal form.

Core Hardness. Core Hardness for AGMA

toot h design purposes is the hardness at the intersec-

tion of the root diameter and the centerline of the

tooth a t mid face width on a finished gear.

D.I. (Ideal Critical Diameter). Ideal critical di-ameter is the diameter which, when quenched in an

infinite quench severity (such as ice brine), will result

in a microstructure consisting of 50 percent marten-

site of the center of the bar.

Decarburization. D ecarburizat ion is the reduc-

tion in surfa ce carbon content o f a gea r or test piece

during thermal processing.


12/79



Ferrite (alpha). Ferrite is a microstructural

phase consisting of essentially pure iron, and is char-

acterized with a body centered cubic structure.

Flame Hardening. Flame Hardening of steel

gea r ing involves oxyfuel b ur ner hea t ing t o

1450---1650 _ F (788 ---899 _ C) followed by quenching

and tempering.

Grain Size. G rain size is specified as either

coarse (grain size 1 through 4) or fine (grain size 5

through 8), determined according to ASTM E112.

Graphite. G raphite is carbon in the free state

with a shape described as either flake, nodule, or

spheroid. The graphite shape classifies the type of

cast iron a s either gray, ductile, or malleable.

Hardenability. An indication of the depth to

which a steel will harden during heat trea tment (see

4.6).

Hardening. The process of increasing hardness,typically through heat ing and cooling.

H---BandSteels.H ---B an d steels ar e steels which

are produced and purchased t o a specified Jo miny

hardenability range.

Induction Hardening. Induction hardening of

gearing is the selective heat ing of gea r teet h profiles

to 1450---1650 _ F (788 ---899 _ C) by electrical induc-tance thro ugh the use of a coil or single to oth induc-

tor to obtain the proper heat pattern and tempera-

ture, fo llowed by q uenching and tempering.

J ominy End Quenching Hardenability Test.The standard method for determining the harden-

ability of steel. The test consists of heating a sta ndard

one inch (25 mm) diameter test bar to a specified

temperature, placing the specimen in a fixture so

that a stream of water impinges on one end, cooling

the specimen to room temperature, grinding flats,

and measuring the hardnessa t 1/16 inch (1.6 mm)in-

tervals starting at the quenched end.

Martensite. Martensite is the diffussionless

transforma tion of austenite to a body centered tetra -

gonal structure, characterized by an acicular

needle ---like appea ra nce.

Microstructure. Microstructure is the material

structure observed on a sample polished to a mirror

finish, etched, and viewed at 100X or higher magnif i-

cation.

Nitriding (Aerated Salt Bath). This term in-

cludes a number of heat treat processes in which ni-

trogen and carbon in varying concentrations are ab-

sorbed into the surface of a ferrous materia l at a tem-

perature below the austenitizing temperature

[1000---1150 _ F (538---621 _ C )], while submerged in agas stirred and activated molten chemical salt bath.

These processes are used mainly for improved wear

resistance and fatigue strength.

Nitriding (Gas). Surface hardening process in

which alloy steel, after machining following quench

and tempering, is subjected to a cracked ammonia

fur na ce a tmo sphere a t 950---1060 _ F (510 ---571 _ C )causing nitrogen to be absorbed into the surface,

forming hard iron nitrides.

Nitrocarburizing.Nitrocarburizing is a gaseous

heat treatment in which both nitrogen and carbon

are absorbed into the surface of a ferrousmaterial at

a temperature below the austenitizing temperature

[1000---1150 _ F (538---621 _ C)]. Nitrocarburizing isdone ma inly for a ntiscuffing and to improve surface

fatigue properties.

Normalizing. Normalizing consists of heating

steel or other ferrous alloys to 1600---1800 _ F(871---982 _ C) and cooling in still or circulated air.Normalizingis used primarily to obtain a uniformmi-

crostructure.

Pearlite. Pearlite is a microstructure consisting

of lamellar layers of ferrite and cementite, with a

body centered cubic crystal structure.

Quench and Temper. The quench and temper

process on ferrous alloys involves heating a part tothe auste nite tra nsforma tion stat e a t 1475---1650 _ F(802---899 _ C), fo llowed by rapid cooling (quench-ing). The part is then reheated (tempered) to a spe-

cifict emperature generallybelow 1275 _ F (690 _ C ) t oachieve the desired mechanical properties for the

gear application.

StressRelief. Stress relief is a thermal cycle used

to relieve residual stresses created by prior heat

treatments, machining, cold working, welding, or

other fa bricat ing techniques. Ma ximum stress relief

is achieved at 1100 _ F (593 _ C) minimum.

Surface Hardness. Surface H ardness is thehardness measured directly on the surface. To obta in

accurate results on shallow case hardened parts, a su-

perficial test must be used.

Tempering. Tempering is reheat ing a hardened

part to a specified temperature, generally below

1275 _ F (690 _ C) to reduce hardness and increasetoughness.


13/79



TestCoupon. A test coupon is an appropriately

sized sample(often a bar) used generally for surface

hardening treat ments. It should be of the same speci-

fied material grade, with regard to composition and

hardenability limits, as the gear it represents. The

test coupon should be heat treated along with the

gear(s) it represents.Through Hardening. Through hardening is a

term used to collectively describe methods of heat

treatment of steelother than surface hardening tech-

niques. These include: annea ling, normalizing (or

normalizing and t empering) and q uenchinga nd tem-

pering (refer to 5.1). D epth of hardening is depen-

dent upon hardenability, section size and heat treat

considerations.

NOTE: Through ha rdening does not imply that

the part has equivalent hardness throughout the en-

tire cross section.

TransformationTemperature.The temperature

at which a change in microstructure phase occurs.

4. Material SelectionGuidelines

Ma ny facto rs influence the selection of materials

for gears, and the relative importance of each can

vary. These factors include:

(1) Mechanical Properties

(2) G rade and H eat Treatment

(3) Cleanliness

(4) Dimensional Stablility

(5) Availability and C ost(6) Hardenability and Size Effects

(7) Machinability and Other Manufacturing

Characteristics

4.1 Mechanical Properties. It is necessary fo r the

gear designer to know the application and design

loadsa nd to calculate the stressesbefore the material

selection can begin.

4.1.1 Hardness. The strength properties are

closely related to material hardness, which is used in

AG MA gear ra ting practice. Surface hardness is an

important consideration for gear wear. Core hard-

ness is an important consideration for bending and

impact strength.

4.1.2FatigueStrength. Conta ct and bending fa-

tigue strengths are used to predict, at a given stress

level, the number of cycles that gearing can be ex-

pected to endure before pitting or fracture occurs.

Contact and bending fatigue strengths are in-

fluenced by a variety of f actors such as ha rdness, mi-

crostructure, material cleanliness, surface conditions

and residual stresses.

4.1.3TensileStrength. Tensile stren gth predict s

the stress level above which fracture occurs. It is not

recommended for use in gear manufacturing specifi-

cations.

4.1.4Yield Strength.Yield strength determines

the stress level above which permanent deforma tion

occurs.

4.1.5 Toughness. Toughness is de termined by

impact strength, tensile ductility and/or fracture

toughness testing. Although not directly considered

in gear rating, toughness may be important for high

impact or low temperature applications or both.

Toughness of stee l gearing is ad versely af fecte d by a

variety of factors such as:

(1) Low temperature(2) I mproper he at trea tment or microstruc ---

ture

(3) High sulfur

(4) H igh phosphorus and embrittling type

residual elements

(5) No nmeta llic inclusions

(6) L arge gra in size(7) Absence of alloying elements such as

nickel.

NOTE: G ear toughness is adversely af-

fected by design or manufacturing consider-

at ions (such as notches, small fillet ra dii, too l

marks, material defects, etc., which act as

stress concentrators).

4.1.6 Heat Treatment. Most wrought ferrous

materials used in gearing are heat treated to meet

ha rdness and/or mechan ical property req uirements.

Round a nd flat stock can be purchased in numerous

combinations of mechanical and thermal processing,

such a s hot rolled, cold rolled, cold drawn, stress re-

lieved, pickled, annealed, and quenched and tem-

pered. G ear blanks are generally given an a nnealing

or normalizing heat treatment, which homogenizes

the micro --- structure f or machinability and mechani-

cal property uniformity. G ear blanks can also be

quenched and tempered.

4.1.7 Stock Removal. All rough ferrous gear

castings, forgings and barstock have a surface layer

containing decarburization, nonmetallic inclusions,

seams, and other surface imperfections. This layer

should be removed from critical gearing surfaces.

The minimum surface stock removal varies with

stock size and t ype of mechanical working. Minimum


14/79



stock removal tables can be found in most machining

and materials handbooks.

4.2 GradeandHeat Treatment. The specific gear

design will usually dictate the grade of material re-

quired as a function of subsequent heat treatment;

such as quench and temper or case hardening. See

Ta bles 4 ---1, 4 ---2, a nd 4---3 for gra des a nd recom-

mended heat treatments.

Table4---1Typical Gear Materials --- WroughtSteel

Common AlloySteel G rades

Common HeatTrea t P ra ctice

G enera l Rema rks/Applicat ion1

1045 T---H , I ---H , F ---H Low H a rdena bility

4130 T---H Ma rgina l H a rdena bility

4140 T---H , T---H &N, I ---H , F ---H Fa ir H a rdena bility

4145 T---H , T---H &N, I ---H , F ---H M edium H a rdena bilit y

8640 T---H , T---H &N, I ---H , F ---H M edium H a rdena bilit y

4340 T---H , T---H &N, I ---H , F ---H G o o d H a rd ena bilit y in H ea vy Se ct io ns

Nitra lloy 135 Mod. T---H &N Specia l H ea t Trea tmentNitra lloy G T---H &N Specia l H ea t Trea tment

4150 I ---H , F ---H , T---H , TH &N Q uench C ra ck Sensitive

G ood Hardenability

4142 I ---H , F ---H , T---H &N U sed when 4140 exhibits

Marginal H ardenability

4350 @ T---H, I ---H, F---H Quench Crack Sensitive, ExcellentHardenability in Heavy Sections

1020 C ---H Very L ow H a rdena bility

4118 C ---H Fa ir C ore H a rdena bility

4620 C ---H G ood C a se H a rdena bility8620 C ---H Fa ir C ore H a rdena bility

4320 C ---H G ood C ore H a rdena bility

8822 C ---H G ood C ore H a rdena bility in H ea vy

Sections

3310 @ C ---H E xcellent H a rdena bility (in H ea vy

4820 C ---H Sections) for a ll three gra des

9310 C ---H

C ---H = Ca rburize Ha rden1

2 Recognized, but not current standard grade.

F ---H = Fla me H arden I ---H = I nduction H arden

T---H = Through Ha rden T---H&N = Through H arden then nitride


15/79



Table4---2

Typical Brinell HardnessRangesandStrengthsfor

Annealed, NormalizedandTempered Steel Gearing

StrengthTensile Y ield

Norma lized & Tempered

StrengthTensile Y ield

@

Strength Strength

#

ksi (MPa)

min min

ksi (MPa)

min

ksi (MPa)

min

ksi (MPa)

Alloy Steels

Annealed H eat Treat ment

BrinellHardness

Range

H B

BrinellHardness

Range

H B

Typica l

Specified1

1045 159---201 80 50 159---201 80 50(550) (345) (550) (345)

4130156---197 80 50 167---212 90 60

8630 (550) (345) (620) (415)

41404142 187---229 95 60 262---302 130 858640 (655) (415) (895) (585)

4145197---241 100 60 285---331 140 90

4150 (690) (415) (965) (620)

4340212---255 110 65 302---341 150 95

4350 Type (760) (450) (1035) (655)

1. Steels shown in order o f increased harde nability.

2. Ha rdening by quench and tempering results in a combination of properties generally superior to t hat

achieved by a nneal or no rmalize and t emper; i.e., impact, ductility, etc.See Table 4---3 for q uench a nd tempered gea ring.

3. Ha rdness and strengths able to be obtained by normalize and tempering are a lso a function of

controlling section size a nd t empering temperat ure considerations.

4.3Cleanliness. Alloy steel manufa ctured with elec-

tric furnace practice for barstock and forged steel

gear applications is commonly vacuum degassed, in-

ert a tmosphere (argon) shielded and botto m poured

to improve cleanliness and reduce objectionable gas

content (hydrogen, oxygen and nitrogen). Improved

cleanliness (reduced nonmetallic inclusion content)

results in improved transverse ductility and impact

strength, but machinability may be reduced; for ex-

ample, with sulfur content less than 0.015 percent.

Vacuum degassed steel may be further refined by

vacuum a rc remelting (VAR) or electroslag remelt-

ing (ESR ) of the steel. These refining processes fur-

ther reduce gas and inclusion size and content for im-

proved fat igue strength to produce the highest q uali-

ty steel for critical gearing applications. Significant

increase in cost and reduced machinability, however,

must be fully evaluated with respect to the need for

improved properties for other than critical gearing

applications.

NOTE: For more informat ion see ASTM

A534 and A535, and AMS 2301 and 2300.

4.4 Dimensional Stability. The process to achieve

the blueprint design ma y require ma terial consider-ations such as: added stock, die steps, restricted

hardenability, etc. to minimize distortion and pos-

sible cracking (see 5.8).

4.5 Cost and Availability. The specific material

selection is often determined by cost and a vailability

fa ctors such as sta ndard industry alloys and procure-

ment time.


16/79



Table4---3

Typical Brinell HardnessRangesand Strengthsfor QuenchedandTemperedAlloySteel

Gearing

Hea t Treatment

Hardness

Range

Tensile Y ield

SteelG r a d e

Strength Strengthminimumksi (MPa)

minimumksi (MPa)

Alloy

*H B [

4130 Wa ter 212---248 100 (690) 75 (515)Quench & up to

8630 Temper 302---341 145 (1000) 125 (860)

4140 Oil 241---285] 120 (830) 95 (655)8640 Quench & up to

Temper 341---38841424145 341---388 170 (1170) 150 (1035)4150

4340 Oil 277---321 135 (930) 110 (760)Quench & up to

4350 Temper 363---415w 180 (1240) 145 (1000)

* Steels shown in order of increased hardenability, 4350 being the highest. These steels can be ordered

to “H” Band hardenability ranges.

[ Ha rdness range is dependent upon controlling section size (refer to a ppendix B ) and q uench severity.] It is difficult to cut t eeth in 4100 Series steels above 341 H B an d 4300 Series steels above 375 HB .

(4340 and 4350 provide advantage due to higher tempering temperatures and microstructure

considerations)

w High specified ha rdness is used f or special gea ring, but costs should be evaluated d ue to reducedmachinability.

The standard wrought carbon and alloy steels

such a s 1020, 8620, 4320, 4820, 9310, 4140, 4150 a nd

4340 are available from service centers and steel

mills. Service centers can usually furnish these mate-

rials in small q uantities and with short d elivery time

from t heir inventories. Steel mill purchases require

“ millq uantities” (several thousand pounds)a nd long

delivery time. Ho wever, the mill qua ntity cost may

be substant ially lower, a nd non ---sta nda rd steels can

be supplied on special request.

When specifying parts with small quantity re-

quirements, standard alloys should be specified or

engineering dra wings should allow optiona l materi-

als. In the case of steel and iron castings and no nfer-

rous materials, SAE and ASTM designations should

be used wherever possible.

4.6Hardenability. Hardenabilityof steelistheprop-

erty that determines the hardness gradient produced

by quenching from the austenitizing temperature.

The a s quenched surface hardness is dependent pri-

marily on the carbon content of the steel part and

cooling rate. The depth to which a particular hard-

nessis achieved with a given quenching condition isa

function of the ha rdenability, which is largely deter-

mined by the alloy content of the steel grade.

4.6.1 Determination. Hardenability is normally

determined by the Jo miny End Q uench Test (ASTM

A255) or can be predicted by the Ideal Diameter(DI) concept.

4.6.1.1 J ominy Test Method. A one inch (25

mm) diamete r bar, f our inches (102 mm) in length is

first normalized then uniformilyhea ted to a standard

austenitizing temperature. The bar is placed in a fix-

ture, then quenched by spraying room temperature

water a gainst one end fa ce.


17/79



4.6.1.2 J ominyAnalysis. Rockwell C hardness

measurements are made along the length of the bar

on ground flats in one sixteenth o f a n inch (1.6 mm)

intervals. J ominy hardena bility is expressed in H RC

obtained at each interval starting at the water

quenched end face.

Example: J5 = 40 is interpreted as a hardnessof 40 H RC at a d istance o f 5/16 inch (8 mm)

from the wa ter q uenched end.

4.6.1.3H---BandSteel. Jominy hardenability has

been applied to stand ard steels. For a given composi-

tion the Jominy hardenability data fallswithin a pre-

dicted range. Ste els purchased to predicted ha rden-

ability ranges are called H ---Ba nd steels. These

B ands are published by ASTM, AISI, and SAE.

Steels can be purchased to H ---B and, or restricted

H ---B an d, specification s.

4.6.1.4 Ideal CriticalDiameter. The Ideal Criti-

calD iameterMethod (DI ) isbased on chemical anal-ysis described in AISI, SAE, M odern Steels and Th eir

Properties by B ethlehem Steel, and other hardenabil-

ity ref erence publications.

4.6.2 Application. Hardenability is constant for

a given steel composition; however, hardness will

vary with the cooling rate. Therefore, the hardness

obta ined at any location on a part will depend on car-

bon content, hardenability, part size, configuration,

quench media, and quenching conditions. Typically a

steel composition is selected with a hardenability

characteristic tha t willyield an as quenched hardness

above the specified hardness so that toughness andmachinability can be a ttained through a ppropriate

tempering. As the section thickness increases, the

steel hardenability must be increased in order to

maintain a given hardness in the part section.

4.7Machinability. Several f actors influence t he ma-

chinability of materia ls and in turn aff ect the econo-

my and feasibility of manufacturing. These fa ctors

must be considered at the design stage, particularly

when high strength levels are being specified. Fac-

tors influencing machinability a re:

(1) M at erial being cut, including composition,microstructure, ha rdness, shape, and size.

(2) C utting speeds, f eeds and cutting tools.

(3) C ondition o f ma chine to ols, including

rigidity, precision, power, etc.

(4) C hara cteristics of the cutting fluid used.

There is abundant material published on ma-

chinability. The mechanics of the cutting operation

will not be considered here. Only metallurgical fa c-

tors will be discussed.

Chemical composition and microstructure of

steel have major influences on machinability, since

they af fect properties and structures. Meta llic oxides

like alumina and silica form hard oxide inclusions

and contribute to poor machinability. E lementssuch

as sulfur, lead, selenium, a nd t ellurium form soft in-

clusions in the steel mat rix and can benefit machin-

ing. Calcium additions (in steel making) form hard,

irregular inclusions and can a lso benefit ma chining.

Ho wever, sulfur, lead and calcium inclusions which

improve machinability can decrease mechanical

properties, particularly in the transverse direction.

Ca lcium treated steel, when used in high stress gearand shaft applications, may significantly reduce fa-

tigue life compared to conventional steelmaking

practices. Ca rbon content over 0.30 percent de-

creases machinability due to increased hardness. D e-

pendent on carbon and sulfur levels, higher manga-

nese also decreases machinability. In genera l, alloys

which increase hardness and to ughness decrease ma-

chinability. The more common gear materials are

listed in Table 4---4 on the basis of good, fa ir, a nd

poor machinability. With good machinability as a

base, a fair rating would add 20 to 30 percent to the

machining cost, and poor would add 40to 50percent.

4.8 FerrousGearing. Ferrous materials for gearing

include carbon and alloy wrought and cast steels, cast

iron and ductile irons. G earing of a lloy and carbon

steel is manufactured from different forms of rough

stock depending upon service, size, design, quantity,

availability, and economic considerations. These

forms include wrought steel, weld fabrications and

castings.

4.8.1 WroughtSteel. Wrought steel is the gener-

ic term applied to carbon and alloy steels which are

mechanically worked into form for specific applica-tions. The standard wrought steel forms are round

stock, flat stock and fo rgings. Forgings reduce ma-

chining time, and are available in a wide range of

sizes and grades.


18/79


2004---B 8910ANSI/AG MA

Table4---4

Machinabilityof CommonGear Materials

Low---Carbon CarburizingSteel Grades --- RemarksMaterial Grades

1020 G ood ma china bility, a s rolled, a s forged, or norma lized.

4118 G o od ma china bilit y, a s rolled, or a s f orged. H owever, no rma lized is4620 preferred. I na deq ua te coo ling during no rma lizing ca n result in gummy8620 ma teria l, reduced t oo l lif e a nd po or surfa ce f inish. Q uench a nd temper8822 a s a prior trea tment ca n a id ma china bility. The economics of the

pretreatments must be considered.

3310 Fa ir to goo d ma china bility if norma lized a nd t empered, a nnea led o r4320 q uenched a nd t empered. No rma lizing wit hout t empering result s in4820 reduced ma china bility.9310

MediumCarbon Through HardenedSteel Grades --- RemarksMaterial Grades

1045 G ood ma china bility if norma lized.11411541

4130 G o od ma china bility if a nnea led, or norma lized a nd tempered to4140 a pproxima tely 255 H B or q uenched a nd tempered to a pproxima tely4142 321 H B . O ver 321 H B, ma china bility is fa ir. Above 363 H B ,

machinability is poor. Ina deq uate (slack) quench with subsequent low tempering temperature may produce a part which meets the specifiedhardness, but produces a mixed microstructure which results in poormachinability.

4145 R ema rks f or medium ca rbon a llo y st eel (a bo ve) a pply. H owever, t he4150 higher ca rbon results in lo wer ma china bility. Sulf ur a ddit io ns a id the4340 ma china bilit y o f t hese gra des. 4340 ma china bilit y is goo d up t o 3634345 H B . The higher ca rbo n leve l in 4145, 4150, 4345, a nd 4350 ma kes4350 them more difficult to ma chine a nd should be specified only for

heavy sections. Ina dequa te (slack) q uench can seriously affe ctmachinability in these steels.

NOTE: Co arse grain steels are more machinable than fine grain. Ho wever, gear steels are generallyused in the fine gra in condition since mechanical properties are improved, a nd distortion during hea ttreat ment is reduced. Increasingly cleaner steels are now a lso being specified for gea ring. However, ifsulfur content is low, less than 0.015 percent, machinability may decrease appreciably.

Other Gear Material --- RemarksMaterial Grades

G ra y I ro ns G r a y ca st iro ns ha ve go od ma china bilit y. H igher st rengt h gra y ca st iro ns[above 50 ksi (345 MPa) tensile strength] have reduced machinability.

D uct ile Irons A nnea led or nor ma lized d uct ile ca st i ron ha s good ma china bilit y. The“as cast” (not heat treated) ductile iron has fair machinability. Quenchedand tempered ductile iron has good machinability up to 285 HB and

fair machinability up to 352 HB . Above 352 HB , ma chinability is poor.

G e ar B r on ze s All ge a r br onze s a nd bra ss h ave go od ma ch ina bilit y. The ve ry h igha nd B r a sse s st re ngt h h ea t t re at ed bro nze s [a bo ve 110 ksi (760 M Pa ) t ensile st re ngt h]

have fa ir machinability.

Aust en it ic All a ust enit ic st a in le ss st ee l gr ad es o nly h ave f a ir ma chin abilit y. B e ca useS ta inless S teel of wor k ha rd ening t endencies, feeds a nd speeds m ust b e select ed t o

minimize work hardening.


19/79


2004---B 8911ANSI/AG MA

4.8.1.1 Round Stock. Round bars can be pur-

chased in various diameters for sta ndard carbon and

alloy grades. They are typically available as hot

rolled, hot rolled ---cold dra wn, hot rolled ---cold fin-

ished a nd f orged rounds. Cold drawing produces a

close tolerance ba r with improved mechanical prop-

erties (higher hardness and yield strength). Low tomedium carbon steels are no rmally a vailable a s cold

dra wn bar for gear ing. Hot rolled ---cold finished bars

are machined (turned, ground and/or polished) fo r

improved size control, but show no improvement in

mechanical properties over hot rolled or annealed

bar. Hot rolled bars are mechanically worked at

a ppro xima te ly 2100---2400 _ F (1150 ---1315 _ C ) a n dmay be subsequently annealed, straightened and

stress relieved. Forged round bars are forged ro und

under a press or ha mmer a t the same a pproximate

temperature as hot rolled bars (higher temperature

for lower carbon content carbon or alloy steel) a nd

are manufa ctured to a size larger than can be formed

with rolling dies or rolls. Forged round bars can be

purchased in a variety of heat treat conditions de-

pending upon applicat ion.

Ho t rolled bars are also now manufactured from

continuouscast steelbar manufactured with continu-

ous casters. Cont inuous cast bar is subsequently hot

rolled with sufficient reduction in cross sectional

area (7 to 1 minimum) during hot deformation to

produce densification and quality bar for many gear-

ing a pplications.

Approximate ma ximum diameter of the various

types of round stock, depending upon steel mill ca-

pacity, is a s follows:

Hot Rolled: 8.0 inch (205 mm)

Cold Drawn: 4.0 inch (100 mm)

Co ld Finished: 5.0 inch (125 mm)

Forged Round: 16.0 inch (405 mm)

Table4---5

Mechanical PropertyRequirements --- Cold Drawn,StressRelievedSteel Bars

(Special Cold Drawn,High Tensile)

Size

inchincluded

SteelDesignation

Tensile StrengthYieldElongation in

percent, min(mm)

NominalHardness

H RC2 inches (50 mm)

w

Mechanical Properties for Rounds, Squares and Hexagons

StrengthMinimum Minimum

ksi (MPa ) ksi (MPa )

1137 SR * 95 (655) 90 (620) 11 24

1045 SR 115 (795) 100 (690) 10 240.375 (10) 1141 SR 115 (795) 100 (690) 11 24

to 1144 SR 115 (795) 100 (690) 10 24

3. 000 (76) 1144 SS[ 140 (965) 125 (860) 10 w 304145 SS] 150 (1035) 130 (895) 10 w 32

3.001 (76.1)

to 4145 SS] 150 (1035) 130 (895) 10 w 323.500 (89)

3.001 (76.1) 1045 SR 105 (725) 90 (620) 9 24

to 1141 SR 105 (725) 90 (620) 9 24

4.000 (102) 1144 SR 105 (725) 90 (620) 9 24

* Stress Relieved.

[ Special steel. Additional requirements: H ardness, Rockwell C 30, min. 1144 SS not available above2.5 in (64 mm).

] Special steel. Additional requirements: Ha rdness Rockwell C 32, min. 4145 SS not a vailable above3.5 in (89 mm).

w Typical value, not a requirement.

NOTE: So me cold finish steel companies furnish many of the a bove steels under various trade na mes.


20/79


2004---B 8912ANSI/AG MA

4.8.1.2Flat or Plate. Commercial flat or plate

steel of numerous carbon and alloy grades is avail-

able in standa rd thicknesses in a wide range of widt hs

and lengths. Flat stock is typically available in hot

rolled or hot rolled and annealed conditions.

4.8.1.3 Forgings. Forgings are made by hot me-

chanical deformation (working of a steel billet into aspecific form) which densifiest he structure, and ma y

provide improved inclusion orientat ion. Typically,

deformation is done while the billet is at tempera-

tures generally above 1900 _ F(1038 _ C ).

Cast ingots, from which blooms and billets are

manufactured prior t o forming forgings a nd bar-

stock, are now also bottom poured as well as conven-

tional top poured. Bottom poured ingots are poured

with a bottom ingate and runner which provides mol-

ten steel to the ingot mold, much like steel castings

are produced. B otto m poured ingots show improved

macro ---cleanliness and ingot yield (more usable in-

got metal after conventional cropping or removal of

the top pipe cavity and bott om discard of to p poured

ingots).

Alloy steel, manufactured by electric furnace

practice using part or all of the cleanlinesstechniques

discussed in 4.3, can result in improved transverse

ductility and impact strength. Forging stock is always

fully killed steel to minimize the occurrence of fis-

sures due to dissolved ga ses during the fo rging pro-

cess.

The sta ndard forging classifications are:

(1) Open D ie Forging. This method produces a

rough dimensioned piece by mechanical deforma-

tion between an upper and lower die (hammer and

anvil) in an open frame press or hammer.

Open die forgings may be specified to be upset

forged to increase center densification. An upset

forging is produced when the billet is initially hot

worked in one direction, and then is rotated 90 de-

grees and hot worked again. U pset forgings are often

used for critical high speed gearing, greater than

30,000 f eet /minut e (152 m/sec) pitch line velocity,which develop high centrifugal stress at the center.

(2) Closed D ie Forging. This method produces a

closer toleranced piece, generally smaller than an

open die fo rging. The upper and lower dies trap the

steel billet in a closed (confined) cavity and the press

action deforms the metal to fill the die cavity, pro-

ducing a more exact contoured forging.

(3) Rolled Ring Forging. This method produces

a do nut ---shaped work piece. Typicallyt he process in-

volves piercing a pa ncake ---shaped billet wit h a man-

drel and shaping the ring by a hammer action be-

tween the mandrela nd the press anvil. Large diame-

ter rings are rolled on a roller press fro m circular bil-

lets conta ining a centra l hole.For additional information on wrought steel

manufacture and steelmaking refining practices, ref-

erence should be made to the f ollowing sources:

American Society for Metals (ASM Internation-

al), M etal H andbooks

American Iron and Steel Institute (AISI), Steel

Products M anual

Forging Industry H andbook, by the Forging In-

dustry Association

4.8.2 Weld Fabrications. Weld fa bricat ed gears

generally consist of rolled or forged rings, formed

plate or castings for the rim (tooth) section, a forged

or cast hub and mild steel plate f or the web or arm

support sections.

The rim or tooth section is heat treated to obta in

specified ha rdness (mechanical properties) prior to

weld assembly. Afte r weld assembly, using appro pri-

ate preheat and postheat temperatures, welded a s-

semblies a re fur na ce str ess relieved a t 950---1250 _ F(510---675 _ C) depending upon the previous temper-ing temperature used to obtain the specified hard-

ness of th e rim section. ASTM A290 should be refer-

enced for ring forgings for fabricated gears.

4.8.3CastSteels.Ca rbon and alloy steelcastings

are used for a wide variety of through hardened gear-

inga nd, to a lesser degree, for case hardened applica-

tion s. The size of cast gea ring varies fro m 10.0 inch

(254 mm) outside diamet er with a 2.0 inch (51 mm)

face width for solid rimgears, to split ring gearsa bout

480inch (12 192 mm) outside diameter with a 40inch

(1016 mm) face. Sma ller gea rs generally have a solid

web and hub design, with possible cored holes in the

web or flange for weight reduction. Larger gears are

usually solid hub, split hub, or split hub and rim de-

sign, which incorporate cast arms rather than the

heavier solid web design used for smaller gears. Still

larger ring gears are solid or split ringdesign withbolt

holes at the splits and on the inside diameter flange

for gear assemblya nd mounting purposes. Split gears

are cast in two or four segments. Typical cast gear de-

signs a re shown in F ig 4 ---1.

4.8.3.1 Manufacture.Ca st steelis manufactured

by the open hearth, electric arc, or induction furnace


21/79


2004---B 8913ANSI/AG MA

melting processes, using both acid or basic lined fur-

nace steel making practices. Secondary refining pro-

cesses can be used for reducing the gas, phosphorus,

and sulfur levels of cast steel.

4.8.3.2 Material GradesofCastSteel. The ma-

terial grades used for cast gearing are generally mod-

ifications (silicon, etc) of standa rd AISI or SAE des-

ignations. Through hardened gearing applications

generally use 1045, 4135, 4140, 8630, 8640, and 4340

type steels. Ca rburizing grades a re usually 1020,

8620 and 4320 types. As with wrought steel, care

must be taken to ensure that the specified cast analy-

sis for through hardened gearing has sufficient

hardena bility to obta in the specified minimum hard-

ness.

Typical chemical a nalyses and tensile propert ies

of through ha rdened cast steels are shown in Tables

4---6 a nd 4---7, respectively.

SMALLER GEARS

LARGER GEARS INCLUDING OPEN GEARING

S OLID WEB C ORED WEB

S OLID RING S P LIT RING

S OLID HUB S P LIT HUB S P LIT HUB AND RING

(NOTE: Each design above can be made by forging or weld fabrication.)

Fig4---1 Typical Designof Cast Steel Gears


22/79


2004---B 8914ANSI/AG MA

Table4---6Typical Chemical Analysesfor ThroughHardened Cast Steel Gears

1045 4140 8630 4340 TypeElement

Type Type Type 8642 Type

Alloy Percent fo r C ast St eel Types

C a rbon 0.40---0.50 0.37---0.43 0.27---0.37 0.38---0.45 0.38---0.43M a nga nese 0. 60---1. 00 0.70---1. 00 0.70---1. 00 0. 70---1. 00 0.70---1.00

P hosphorus, ma x. 0.050 0.030 0.030 0.030 0.030

Sulfur, ma x. 0.060 0.040 0.040 0.040 0.040

Silicon, ma x. 0.60 0.60 0.60 0.60 0.60

Nickel --- --- --- --- 0.60---0.90 0.60---0.90 1.65---2.00

C hromium --- --- 0.80---1.10 0.60---0.90 0.60---0.90 0.70---0.90

M olybdenum --- --- 0.15---0.25 0.30---0.40 0.40---0.50 0.20---0.30

GENERAL NOTES:

1. Type designations indicate non ---conformance to exact AISI ana lysis requirements.2. When basic steel making practice, ladle refining or AOD (argon oxygen decarburization) processing

are used, lower phosphorus and sulfur content s to less tha n 0.020 percent are commonly a chieved.

3. Van ad ium cont ent of 0.06---0.10 percent may be specified for gra in refinement .

4. Aluminum content o f 0.025 percent maximum may be specified fo r low a lloy cast steel (per ASTM

A356) for ladle deoxidation to improve toughness, cleanliness and machinability.

5. Ot her AISI Type and proprieta ry chemical ana lyses are used for carbon and low alloy cast gears

according to ASTM A148 or customer specifications, depending upon specified hardness (mechanical

properties), type of heat treat ment a nd controlling section size (hardena bility) considerations.

6. Source: AG MA 6033---A88, Standard for M arine Propulsion G ear Uni ts, Part 1 Materials .

Table4---7TensilePropertiesof ThroughHardened Cast Steel Gears!

BrinellHardness

RangeClass

Ten sileStrength

ksi (MPa)

YieldStrength

0.2 percent O ffsetElongation

in 2 in(50 mm)

Reductionin Area

Minimum Minimum

MinimumPercent

MinimumPercent

A G MA@

6033---A87

ksi (MPa)

A 223---269 100 (690) 75 (480) 15.0 35.0

B 241---285 110 (760) 80 (550) 13.0 31.0

C 262---311 118 (810) 90 (620) 11.0 28.0

D 285---331 130 (900) 100 (690) 10.0 26.0

E 302---352 140 (970) 115 (790) 9.0 24.0

F 321---363 145 (1000) 120 (830) 8.0 20.0

G 331---375 150 (1030) 125 (860) 7.0 18.0

NOTES:

1. Above tensile requirements for seven classes are modifications of three grades of ASTM A148

(G ra des 105---85 th rough 150---135).

2. Sour ce: AG MA 6033---A88, Standard for M arine Propulsion G ear Un its, Part 1 M aterials .


23/79


2004---B 8915ANSI/AG MA

4.8.3.3 Repair Welding of Cast Steel. Repair

welding of castings prior to heat t reatment is rou-

tinely performed by the casting producer. Repairs in

the rim (tooth) portion and other critical load bear-

ing locations should be performed only prior to heat

trea tment. H eat treat able electrodes (4130, 4140a nd

4340 Types) should be used f or repairing prior t oheat trea tment in order to produce hardness equiva-

lent to the base metal after heat treatment. Repair

welding, if allowed aft er heat t reatment, shall be fol-

lowed by reheat trea tment, whenever possible. I f re-

heat treat ment is not possible, localized preheat a nd

post heat are recommended to avoid or minimize un-

fa vorable residual t ensile stress or high ha rdness in

the heat a ffected zone. All welds should be inspected

to the same qua lity standa rd used to inspect the cast-

ing.

NOTE: Weld repair in the too th portion ma y

require notification of the purchaser.

4.8.3.4 HeatTreatment of Cast Steel. Castings

are heat treated to either a specified hardness or to

specified hardness and minimum mechanical prop-

erties. The minimum number of hardness tests re-

quired o n both rim fa ces of gear ca stings is generally

based on t he outside diameter. The number of tests

increases with O D size. M echanical property tests

(tensile and impact) a re generally required only

when specified. Reference should be made to 6.2and

6.3 for additional information.

4.8.3.5 QualityofCastSteel. C astings should be

furnished free of sand, scale, extraneous append-

ages, a nd ha rd a reas resulting from arc---airing, gas

cutting, and repair welding which could adversely af -

fect machining. Casting should also be free of cracks,

hot tears, chills, and unfused chaplets in the rim sec-

tion. C astings must meet the nonde structive test re-

quirements in the rim section. The q uality specified

in other than the rim (tooth) section is often less

stringent. Minor discontinuities in finish machined

teeth, if present, are often contour ground for re-

moval, in preference to cosmetic weld repair. Ap-

proval by the customer may be required.

D ry or wet fluorescent magnetic pa rticle inspec-

tions are routinely performed t o meet specified sur-

face quality requirements. Other nondestructive

testing, such as radiograph and ultrasonicinspection,

is performed to evaluat e internal integrity of the rim

(tooth) section when specified. Metho ds of testing,

test locations, and acceptance standards are estab-

lished between the purchaser and manufacturer.

Recommended ASTM specifications for nonde-

structive inspection test procedures are:

ASTM E709---80, Magnetic Particle Examination

ASTM E 125---63 (1980), Reference Photographs

for M agnetic Particle Indi cations on Ferrous Castings

ASTM A609---83, Ul trasonic Examination of

Carbon and L ow A lloy Steel Castings


graphs for H eavy Walled [ 2 to 41/2 i nch) (51 to 114

mm )] Steel Castings


graphs for H eavy Walled [ 4 1/2 to 12 in ch(114 to 305

mm )] Steel Castings


graphs for Steel Castings U p to 2 inch (51 mm) in

Thickness

4.8.3.6 Additional Information for Cast Steel.

Information is available in:ASM Handbook series, Volume 5, 8th edition,

Steel Founder’s Society of America (SFSA) Publica-

tion

ASM Handbook, Volume 11, 8th edition, Non-

destructive I nspection and Qu ality Control

4.8.4 CastIron. Ca st Iron is the generic term for

the fa mily of high carbon, silicon, iron alloys. The

fa mily of cast irons is classified by the following cate-

gories.

4.8.4.1 GrayIron. G ray iron conta ins (typically

over 3.0 percent) carbon, which ispresent as graphite

flakes. It is chara cterized by the gra y color occurring

on a fracture surface. Refer to Grayand DuctileIron

Castings H andbook for additional information.

(1) Material considerations. C ast ironsf or gears

are made by t he electric arc furnace, cupola, or in-

duction practice and should be free of shrink, poros-

ity, gas holes, entrapped sand and hard a reas in the

tooth portion.

Repair welds in areas to be machined should

have machinability eq uivalent to the casting. Repair

welds in the t ooth portion should only be performed

with the approval of the gear purchaser.

(2) Hea t Treat ing. Ca st iron castings are gener-

ally furnished as cast unless otherwise specified.

Stress relieving may be deemed necessary to hold

close dimensional to lerances. It is recommended

t ha t ca st ings b e hea t ed t o 1000 t o 1100 _ F(538---593 _ C), holding at temperature up to onehour per inch of maximum section and furnace

cooled to below 600 _ F (315 _ C ).


24/79


2004---B 8916ANSI/AG MA

(3) Chemical Analysis. U nless otherwise speci-

fied, t he chemical a nalysis is left to the discretion of

the casting supplier as necessary to produce castings

to the specification.

(4) Mechanical Properties. Ca st iron gears are

rated a ccording to AG MA practice based on ha rd-

ness. Therefore, hardness determines the rating of

the gear.

Minimum hardness requirements for t he classes

of cast iron a re sho wn in Ta ble 4---8.

Hardness tests should be made in accordance

with ASTM E 10. Ha rdness tests should be made on

the mid rim thickness or mid face width of the too th

portion diameter. At least one hardness test should

be made o n each piece, and sufficient hardness tests

should be made to verify that the part meetsthe mini-

mum hardness specified. Specified minimum hard-

ness must be maintained to the finish machined di-

mensions fo r a cceptance.

Tensile tests should only be required when speci-

fied. Tensile t est requirements a re shown in Table

4---8, an d t esting should be perfo rmed in accord ance

with ASTM A48, Standard Specifications for G ray

Iron Casting .

Tensile test coupons are cast in separate molds in

a ccordan ce with the provisions of ASTM A48. The

size of the cast test coupon is dependent upon the

thickness of the tooth portion of the casting as fol-

lows:

Thicknessof Too thSection,

As CastDiameter,

in (mm)

MachinedDiameter, ASTM A48

Test B ar ,in (mm)in (mm)

0.25---0.50 0.88 0.50 A

(6. 4--- 12. 7) (22. 4) (12. 7)

0.51---1.00 1.20 0.750 B

(12.8---25.4) (30.5) (19.0)

1.01---2 incl. 2.00 1.25 C

(25.5---50.8) (50.8) (31.8)

NOTE: See ASTM A48 for tolerances on a s

cast and machined diameter and retest con-

siderations if bar fails to meet requirements.

Table4---8

MinimumHardness and TensileStrength

Requirements

for GrayCast Iron

ASTMClass

Number

BrinellHardness

Ten sileStrength

ksi (MPa)

1

20 155 20 (140)

30 180 30 (205)

35 205 35 (240)

40 220 40 (275)

50 250 50 (345)

60 285 60 (415)

1 See ASTM A48 for additional information.

4.8.4.2DuctileIron. D uctile iron, sometimes re-ferred to as nodular iron, is characterized by the

spheroidal shape of the graphite in the meta l matrix,

produced by innoculation with ma gnesium and rare

eart h elements. A wide ra nge of mechanical proper-

ties a re produced through control of the alloying ele-

ments and subsequent heat treatments. (Refer toGray and D uctile Iron H andbook .)

(1) Material Considerations. Ductile iron cast-

ings are made by the electric arc furnace, cupola or

induction practice and should be free of shrink, po-

rosity, gas holes and entrapped sand and hard areas

in the tooth portion.

Repair welds in areas to be machined should

have eq uivalent ma chinability as the casting. Repair

welding in the tooth portion should only be per-

formed with the approval of the gear purchaser.

(2) Hea t Treating. D uctile iron castings shall be

heat treated by annealing, normalizing and temper-ing or quenching a nd tempering or as ---cast a s re-

quired t o meet the specified mechanical properties.

These heat treatments produce ferritic, pearlitic or

martensitic structures.

(3) Chemical Analysis. U nless o therwise speci-

fied, t he chemical a nalysis is left to the discretion of

the casting supplier as necessary to produce castings

to the specification.

(4) Mechanical Properties. Typical mechanical

propert ies are shown in Table 4---9. Ot her pro perties

may be as agreed upon by the gear manufacturer and

casting producer.

Tensile test coupo ns should be poured fro m the

same ladle or heat and be given the same heat treat-

ments a s the castings they represent. Test coupon

mold design shallbe in accordance with ASTM A536.

Size of the Y ---block mold, if used, is a t the optio n of

the producer unless specified by the gear manufac-

turer.


25/79


2004---B 8917ANSI/AG MA

Tensile tests should be perf ormed in accorda nce

with ASTM D esignation E8, Standard M ethod of Ten-

sion Testing of M etallic M aterials . The yield strength

is normally determined by the 0.2 percent offset

method. For required retesting, if tensile bar fa ils to

meet requirements, refer to ASTM A536.

Hardness tests should be performed in accor-

dance with ASTM D esignat ion E 10, Standard Meth-

od of Test for Brin ell H ardness of M etalli c M aterials .

H ardness tests should be made on the mid rim thick-

ness or mid fa ce width of the tooth portion diameter.

Number of hardness tests per piece is based on the

diameter of the casting as follows:

Outside D iameterof Casting, in(mm)

Number o fH ard ness Tests

To 12 (305 ) 1

O ver 12 (305) to 36 (915) 2

O ver 36 (915) t o 60 (1525) 4

O ver 60 (1525) 8

When two hardness tests are required, one

should be mad e on t he cope side over a riser and the

other on the drag side approximately 180 degrees

away between risers. When four hardness tests are

required, t wo tests should be ma de on the cope side,

one over a riser and the ot her approximately 180de-

grees away between risers, and two testson the drag

side 90 degrees away from the testson the copeside.

When eight hardnesst ests are specified, they shallbe

made 90 degrees apart on both cope and drag side.

For solid cylindrical pieces, with length over di-

ameter of one or more, the number of ha rdness tests

should be as follows:

DiameterToot h Po rtion , in(mm) Number o fH a rdness Testsof

To 3 (76) incl. 1

O ver 3 (76) t o 6 (152) incl. 2

Over 6 (152) 4

NOTE: The hardness tests shall be spaced

uniformly a round the circumference.

When many smallpieces are involved, all poured

from the same ladle or heat, and heat treated in a

single furnace load , a sample testing plan is generally

used with the approval of the

gear manufacturer.

4.8.4.3 Austempered Ductile Iron. Austemp-ered D uctile Iro n (ADI ) is a d uctile iron with higher

strength and hardness tha n conventional ductile

irons. The higher properties of AD I a re a chieved by

closely controlled chemistry a nd an austempering

heat treatment. This treatment results in a unique

microstructure of bainitic ferrite and larger amounts

of carbon stabilized austenite. With variation in aus-

tempering temperature and transformation time,

several ranges of engineering properties can be

achieved.

Table4---9Mechanical Propertiesof DuctileIron

BrinellHa rdness Ra nge

ClassStrength

Elongationin 2 inch

AGMAFormer

percent min

ASTMG r a d e

Designation

RecommendedHea t Treat ment

Min. Yield

ksi (MP a ) ksi (MP a ) (50 mm)

1Mi n. Tensile

Strength

60 --- 40--- 18 A --- 7--- a An ne ale d Fe rrit ic 170 ma x. 60 (415) 40 (275) 18. 0

65---45---12 A---7---b As---Cast or Annealed 156---217 65 (450) 45 (310) 12.0

Ferrit ic---Pe a rlitic

80---55---06 A---7---c Normalized Ferritic---Pearlitic 187---255 80 (550) 55 (380) 6.0

100---70---03 A---7---d Quench & Tempered Pearlitic 241---302 100 (690) 70 (485) 3.0120--- 90--- 02 A --- 7--- e Q ue nch & Te mpe re d R a nge 120 (830) 90 (620) 2. 0

Ma rtensitic Specified

1 See ASTM A536 or SAE J 434 for further info rmation.

NOTE:Ot her tensile properties and hardnesses should be used only by agreement between gear manufa cturer

and casting producer.

ADI has been utilized in several significant ap-

plications, such as automotive ring gears and pinions,

but is still an emerging technology. AD I permits low-

er machining and hea t trea t cost and replacement of

more costly forgings for certa in a pplications.


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2004---B 8918ANSI/AG MA

Test programs ar e currently underwa y which will

more clearly define operational properties of ADI.

4.8.4.4 MalleableIron. M alleable iron is a heat

treated white (chilled) iron which can be produced

with a range of mechanical properties depending on

the alloying practice and heat treatment. This has

generally been replaced by ductile iron. (Refer toASTM A220.)

4.8.5Powder Metal (P/M). Powder metal parts

are formed by compressing metal powders in a die

cavity and heat ing (sintering) the resulta nt compact

to metallurgically bond the powder particles. Sec-

ondary operationssuch as repressing or sizing may be

used to obta in precise control of shape and size or to

improve mechanical properties.

The powd er meta l process is used to re duce cost

by eliminat ing machining operat ions

ANSI-AGMA 2004-B89-Gear Materials and Heat Treatment Manual

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Transcript of ANSI-AGMA 2004-B89-Gear Materials and Heat Treatment Manual