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FEM SIMULATION OF SURFACE HARDENING TECHNIQUES - 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
INTRODUCTION
SURFACE HARDENING TECHNIQUES
CASE STUDY#1 : HEAT TREATMENT OF A BEVEL GEAR
CASE STUDY#2 : INDUCTION HARDENING OF A SPUR GEAR
CONCLUSION & PERSPECTIVES
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
OUTLINE
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
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
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
INTRODUCTION
Recent challenges - Predict the ‘in-use’ properties of the forgings
- Simulate the entire manufacturing process including all pre & post-forming operations (from initial heating to final heat treatment) Today’s presentation - Illustrate a wide range of heat treatment simulations - Application to surface hardening on forged components
INTRODUCTION
SURFACE HARDENING TECHNIQUES
CASE STUDY#1 : HEAT TREATMENT OF A BEVEL GEAR
CASE STUDY#2 : INDUCTION HARDENING OF A SPUR GEAR
CONCLUSION & PERSPECTIVES
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
OUTLINE
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
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
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
SURFACE HARDENING TECHNIQUES
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
SURFACE HARDENING TECHNIQUES
Application of surface hardening on gear components Very located and non-constant contact area
Need to increase hardness on the surface
Need 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.howstuffworks.com/transport/engines-equipment/gear2.htm
INTRODUCTION
SURFACE HARDENING TECHNIQUES
CASE STUDY#1 : HEAT TREATMENT OF A BEVEL GEAR
• CARBURIZING -> QUENCHING -> TEMPERING
CASE STUDY#2 : INDUCTION HARDENING OF A SPUR GEAR
CONCLUSION & PERSPECTIVES
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
OUTLINE
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
CASE STUDY#1 : AUTOMOTIVE BEVEL GEAR
Complete forming sequence description Two warm forging stages
Piercing-Flash trimming, Machining
Heat treatment operations (carburizing-quenching-tempering)
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
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 850°C
– Initial carbon rate in the part : 0.20%
– Atmosphere enriched in carbon : 0.8%
• Quenching
– Oil bath : 20°C during 2min
– HTC : 5500 W/°C.m2
• Tempering
– To relieve internal stresses : 200°C during 40min
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
CASE STUDY#1 : CARBURIZING STAGE
Objectives of the carburizing stage Increase of carbon concentration on surface
Increase quenchability for low carbon steel
0.20% carbon
~
Low
quenchability
0.80% carbon
~
High
quenchability
Isothermal diagram is shifted according to the carbon rate
from 0.20% to 0.8% of C
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
CASE STUDY#1 : CARBURIZING RESULTS
Carbon concentration (%)
after carburizing
Carburizing
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
CASE STUDY#1 : QUENCHING RESULTS
Phase distribution after oil quenching
(martensite-bainite-pearlite-ferrite) Residual stress distribution
(1st principal stress)
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
CASE STUDY#1 : PART DISTORTION
Distortion observed on the component after quenching due to plastic deformation
(magnification x10)
Quenching
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
CASE STUDY#1 : TEMPERING RESULTS
Effective stress relieving due to tempering
- before (left) & after (right) -
Von Mises stress (MPa)
Tempering
INTRODUCTION
SURFACE HARDENING TECHNIQUES
CASE STUDY#1 : HEAT TREATMENT OF A BEVEL GEAR
CASE STUDY#2 : INDUCTION HARDENING OF A SPUR GEAR
• LOCAL HEATING BY INDUCTION -> QUENCHING
CONCLUSION & PERSPECTIVES
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
OUTLINE
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
CASE STUDY#2 : STRAIGHT-CUT OR SPUR GEAR
Typical ‘in-use’ conditions with loading / unloading sequence
Alternative ‘compression vs. tension’ mode at the root of the teeth
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
CASE STUDY#2 : STRAIGHT-CUT OR SPUR GEAR
How to increase the resistance to fatigue loading for contact fatigue : increase local hardness
for bending fatigue : increase compressive residual stress
Objective : delay cracks propagation
Material characteristics
Resisting torque = 1000 N.m
Yield stress = 600 Mpa
Ultimate stress = 800 Mpa
Elongation at break = 5 %
Pressure distribution
Red => compression
Blue => tension
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
CASE STUDY#2 : HEAT TREATEMENT SEQUENCE
Heating (induction) Tempering (induction) Quenching (water jets)
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
INDUCTION HEATING : FEM SOLVERS
Heating
Electro magnetic solver FORGE® Solver Heating source
Temperature
Air
Inductor
Workpiece Only workpiece
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
INDUCTION HEATING : GLOBAL MESHING TECHNIQUE
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)
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
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.m2
– Media temperature : room temperature
– Time : 15min
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
CASE STUDY#2 : RESULTS
Heating (induction)
Heat power (W/m3) Magnetic field (A/m)
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
CASE STUDY#2 : RESULTS
Heating (induction)
Temperature (deg C) Austenite rate
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
CASE STUDY#2 : RESULTS
Heating (induction)
Low frequency High frequency Heating time is longer Heating time is shorter
Preferential heating zone: tooth base Preferential heating zone: tooth tip
𝑰𝒓𝒎𝒔= 4000 A
f = 5 kHz
Heating time = 10 sec
Austenite distribution Austenite distribution
Dual frequency ? 𝑰𝒓𝒎𝒔= 4000 A
f = 20 kHz
Heating time = 2 sec
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
CASE STUDY#2 : RESULTS Heating (induction) Quenching (water jets)
Martensite rate Temperature (deg C)
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
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 2 2,5 3
Depth
Residual stresses (Mpa) 𝒕𝒆𝒏𝒔𝒊𝒐𝒏
𝒄𝒐𝒎𝒑𝒓𝒆𝒔𝒔𝒊𝒐𝒏
0
100
200
300
400
500
600
700
800
0 0,5 1 1,5 2 2,5 3
Hardness (HV)
Depth
Final material properties by the quenching end
INTRODUCTION
SURFACE HARDENING TECHNIQUES
CASE STUDY#1 : HEAT TREATMENT OF A BEVEL GEAR
CASE STUDY#2 : INDUCTION HARDENING OF A SPUR GEAR
CONCLUSION & PERSPECTIVES
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
OUTLINE
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
CONCLUSION & PERSPECTIVES
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 transformation. - Induction hardening (heating + quenching). - Right compromise for process parameters.
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014
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, hardening, heat treating, …
Keep increasing our competitive advantages with : - Enhanced phase transformation models - Complementary surface treatment : nitriding, carbonitriding - Precipitate prediction incl. coupling with strain & stress
THANK YOU FOR YOUR ATTENTION
ADDRESS: 694, av du Dr. Maurice Donat
Parc de Haute Technologie 06255 Mougins cedex
France
CONTACT: +33 (0)4 9292 4200 +33 (0)4 9292 4201
[email protected] http://www.transvalor.com/
5th Asia Forge Meeting - Kaohsiung (Taiwan) - November 3-6, 2014