Induction hardening of gearwheels made from … 1627 Workshop Hannover, 30.09.-02.10.13 Induction...

IRTG 1627 Workshop Hannover, 30.09.-02.10.13

Induction hardening ofgearwheels made from42CrMo4 hardening andtempering steel byemploying water-air spray coolingProject A3 IRTG 1627 „Virtual Materials and Structures and their validation“


Contents

Introduction

Motivation

Modelling of spray cooling and verification

Objectives

Conclusion/Outlook

Experimental investigations


Induction hardeningPrincipleHardening of the surface layer

Heating for ferrite-austenite transformation

Rapid cooling for martensite formation

Heating duration of 0.1 s to 1 s

No phase transformation in the core

AdvantagesEnergy saving

Increase of wear resistance and fatigue strength

Minimization of size changes

Reduction of post-hardening machining Time-temperature profiles duringinduction hardening

900

Time in s

Tem

pera

ture

in °

C

1

surface

core


Induction heating by simultaneous dual frequency method

Induction heating with MF Induction heating with HF

Working principleSimultaneous transmission of two oscillating electromagnetic

fields to a component surface layer

Tooth crest region: high frequency (HF) of 150 kHz to 350 kHz for hardening depths of 0.3 mm to 1 mm

Tooth root region: middle frequency (MF) of 10 kHz to 25 kHz for hardening depths up to 2 mm

A: Inductor current (HF, MF)B: HF-, MF-currents in the workpieceC: Heating of tooth crest by HF and of

tooth root by MFσ: Current penetration depth

Heating by an inductor


QuenchingState of the artInduction hardening by employing water-polymer solutions

Soft spot formation

Complicated handling

Bad skin compatibility of polymer solutionsAlternativeSubstitution of water-polymer quenching by water-air spray cooling

Water-air spray coolingGood controllability of the quenching processSelf-tempering (tempering from the residual heat)

Renunciation of polymer-solutionEnviromental compatibilityCost saving

Low distortion

Quenching by water-polymer solution

Quenching by water-air spraycooling


Contents

Introduction

Motivation


Objectives

Conclusion/Outlook



Problem definition

Motivation Complicated handling of the quenching process by water-polymer solutions

High procurement and disposal costs of polymer-solutions

Need of an economic quenching method with high controllability

Until now engineering of spraying fields is based on empirical investigations

Spraying field concept for induction hardening machine


Project objectives

Integration of water-air spray cooling in the process of induction hardening

Numerical model of induction hardeningby water-air spray cooling Consideration of thermal, microstructural and

mechanical interactions

Model implementation in commercialsimulation software ANSYS Workbench 13.0 Macros in Ansys Parametric Design Language (APDL)

Simulation results verification by experiments


Contents

Introduction

Motivation


Objectives

Conclusion/Outlook



Experimental setup and test workpieceSprayfield Variability of nozzle number from 6 to 12 Water and air pressure adjustable from

0.1 MPa to 0.6 MPa Variability of distance between the workpiece

and the nozzles Control by an industrial PC using LabView

Spur and helical gearwheels of 42CrMo4


Induction hardening by employing spray cooling


Experimental results

water-polymer water-air sprayResidual stresses

Hardness profiles in the tooth crestMacrograph of induction hardened gearwheelby employing spray cooling

Distortion


Cost analysis of the quenching process

0

1000

2000

3000

4000

5000

6000

7000

calc. depreciation calc. interest room costs energy costs maintenance andrepair costs

Mac

hine

rela

ted

over

head

cos

ts in

€/a spray field

polymersprinkler

Machine-hour schedules Spray field approx. 4 € Polymer sprinkler approx. 5 €

Quenching costs per gear0.0078 €0.01 €


Self-tempering (tempering from the residual heat)

Residual stresses

Distortion

Tempered martensite in the tooth crest

Hardness profiles in the tooth crestFurnace tempering Self-tempering


Contents

Introduction

Motivation


Objectives

Conclusion/Outlook



Model-relevant processes

Induction heating

Quenching by water-air spray cooling

Microstructure

Temperature

Temperature

Residual stresses

DistortionHardness

11 Temperature induced

phase transformation2

2Transformation heat

3

3 Thermal stresses

4 Deformation heat

4

5

5

Transformation stresses6

6

Stress induced transformation


Temperature profile approximation after heating


Verification of heating simulation results

1 2 34

5 6

Measured surfacetemperature

EXP [°C] FEM [°C]926.38 932.64

Point 1 Point 2 Point 3 Point 4 Point 5 Point 6

EXP [°C] 828.60 726.40 599.50 999.50 414.70 56.90

FEM [°C] 831.91 724.24 615.20 854.56 369.47 44.38

Simulated surfacetemperature


Modelling of austenite formation

Volume fraction of austenite fordifferent heating rates [Miokovic et al. 2006]

6000 K/s

Variable Valuea -3.04E-12b 1.77E-08c -4.40E-05d 0.06083996e -50.4051351f 25039.0195g -6905494.06h 815651113


Modelling of spray cooling

Temperature dependent heat transfercoefficients during quenching [Krause et al. 2008]

Temperature development during cooling

Wär

meü

berg

angs

koef

fizie

nt in

W m

-2K

-1

Temperatur in °C

0 100 200 300 400 500 600 700 800 9000 100 200 300 400 500 600 700 800 9000

5000

10000

15000

20000

25000

0

5000

10000

15000

20000

25000

1

2

3

4

5

6

7

Wasserdruck Luftdruck1 0,5 MPa 0,3 MPa2 0,6 MPa 0,5 MPa3 0,6 MPa 0,3 MPa4 0,6 MPa 0,6 MPa5 0,3 MPa 0,6 MPa6 0,3 MPa 0,3 MPa7 0,1 MPa 0,3 MPa

Water Air

Temperature in °CHea

ttra

nsfe

rcoe

ffici

enti

n W

·m-2

K-1


Verification of cooling simulation results

T, °C

T, °CT, °CT, °C

T, °CT, °C

t, s t, s t, s

Point 1

Point 4

Point 2

Point 5

Point 3

Point 6


Modelling of austenite-martensite transformation

The Koistinen-Marburger equation:ξM = 1 – exp[-k(Ms – θ)]

ξM - martensite fractionk - constant related to steel compositionMs - martensite starting temperature

θ - temperature

Martensite formation during cooling

TTT-diagram of 42CrMo4 steel for continuous cooling[Werkstoffdatenblatt 42CrMo4 (1.7225) 2010]

Model assumption

No diffusional phase transformation


Modelling of hardness

Variable Valuea 324.878598b -0.00862882c 3.24E-05

Relationship between the hardness and the martensite fraction[Nürnberger 2010]


Verification of hardness simulation results

Schematic of hardness measurements Tooth crest

Tooth flank Tooth root


Modelling of residual stresses and distortion

(εij)tot = (εij)el + (εij)pl + (εij)th + (εij)tr + (εij)

(εij)tot total strain

(εij)el elastic strain

(εij)pl plastic strain

(εij)th thermal strain

(εij)tr transformation induced strain

(εij) transformation induced plasticity

Elastic-plastic model

Model assumptions

Low deformation heat

No stress induced transformation

tp

tp

Distortion Residual stresses


Contents

Introduction

Motivation


Objectives

Conclusion/Outlook



Conclusion/Outlook

ConclusionSubstitutionability of water-polymer quenching by water-air spray cooling in the

process of induction hardening was proved

Economic analysis of the quenching process

Self-tempering by employing spray cooling

Model describing the quenching process by water-air spray cooling after inductionheating was presented

Consideration of thermal, microstructural and mechanical interactions

Simulation results were verified by experiments

OutlookWear resistance and fatigue strength behaviour

Modelling of self-tempering


Thank you for your attention!


ReferencesKoistinen, D.P., Marburger, R.E.: A general equation prescribing the extent of the austenite-martensite transformation in pure iron-carbon alloys and plain carbon steels. Acta Metallurgica, Vol. 7, pp. 59 – 60, 1959

Krause, C., Wulf, E., Nürnberger, F., Bach, F.-W.: Wärmeübergangs- und Tropfencharakteristik für eine Spraykühlung im Temperaturbereich von 900-100 °C. Forschung im Ingenieurwesen, Vol. 72, pp. 163 – 173, 2008

Miokovic, T.; Schulze, V.; Vöhringer, O.; Löhe, D.: Prediction of phase transformations during laser surface hardening of AISI 4140 includingthe effects of inhomogeneous austenite formation. Materials Science and Engineering A 435-436, pp. 547-555, 2006

Nürnberger, F.: Vorhersage von Mikrostruktur und mechanischen Eigenschaften präzisionsgeschmiedeter Bauteile bei einer integriertenWärmebehandlung. Dissertation, Gottfried Wilhelm Leibniz Universität Hannover, 2010

Rodman, D., Krause, C., Nürnberger, F., Bach, Fr.-W., Haskamp, K., Kästner, M., Reithmeier, E.: Induction Hardening ofSpur Gearwheels Made from 42CrMo4 Hardening and Tempering Steel by Employing Spray Cooling. Steel Research International,Vol.82, Nr. 4, pp. 329 – 336, 2011

Gretzki, T.; Rodman, D.; Wolf, L.; Dalinger, A.; Krause, C.; Hassel, Th.; Bach, Fr.-W.: Economic surface hardening by spray cooling.HTM - Journal of Heat Treatment and Materials 66, Nr. 5, pp. 290–296, 2011

Rodman, D.; Krause. C.; Nürnberger, F.; Bach, Fr.-W.; Gerdes, L.; Breidenstein, B.: Investigation of the surface residual stresses inspray cooled induction hardened gearwheels. International Journal of Materials Research, Vol. 103, Nr. 1, pp. 73-79, 2012

Rodman, D.; Nürnberger, F.; Dalinger, A.; Schaper, M.; Krause, C.; Kästner, M.; Reithmeier, E.: Tempering Induction Hardened42CrMo4 Steel Helical Gearwheels from Residual Heat Using Spray Cooling. Steel Research International, pp. 1-11, 2013,DOI: 10.1002/srin.201300133

Rodman, D.; Boiarkin, V.; Nürnberger, F.; Dalinger, A.; Schaper, M.: Modeling of Spray Cooling during Induction Hardening of Spur Gearwheels Made from 42CrMo4 Hardening and Tempering Steel. Steel Research International, pp. 1-15, 2013, DOI: 10.1002/srin.201300201

Schwenk, W.R.: Simultaneous Dual-Frequency Induction Hardening. Heat Treating Progress, April/May, 2003


ReferencesWeise, A.: Entwicklung von Gefüge und Eigenspannungen bei der thermomechanischen Behandlung des Stahles 42CrMo4. Dissertation,Technische Universität Chemnitz, 1998

Werkstoffdatenblatt 42CrMo4 (1.7225). Dr. Sommer Werkstofftechnik GmbH, Anwendungsinstitut zur Einsatzoptimierung von Werkstoffen, Verfahren, Wärmebehandlung, Issum, 2010

Induction hardening of gearwheels made from … 1627 Workshop Hannover, 30.09.-02.10.13 Induction...

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