Tendances & évolutions sur matériaux et traitements aux USA

AIR LIQUIDE - BODYCOTE seminar, in Lyon, Octobre 16 & 17

Richard D. Sisson Jr.Director of CHTE

1

� Status of the industry – automotive, aerospace etc.

� Identify the trends in thermal treatment

Outline

�Discuss these topics

�What did I miss?

2

• “It payeth not for a prophet

to be too specific”

3

Status of the Industry

• Low Pressure Processes have been and are being

used, expansion seen for new equipment

• High Pressure Gas Quenching – not used for critical

partsparts

• Energy savings and the enviroment are a priority

• Cycle time reductions are also a priority

• High Quality is demanded

• Not eager to be the first adopter!

4

Main trends in US industry regarding HT

process and materials?

• Low pressure process versus atmospheric treatments

• Low temperature process (nitriding,..)• Low temperature process (nitriding,..)

• Quenching : gaseous versus / liquid

• Sintering process : developing or not ?

• 3D-manufacturing of metallic components : booming ?

5

Emerging industry needs

• Automation and Robotics

• Advanced Materials

– Fixtures, baskets, rollers and tubes

– Gas quenched parts need high hardenability

• Modeling and Simulation + Data

• Sensors and Controls

• Process Intensification

– Reduced cycle times

– Single part flow

• Heat Generation Methods

– Better burners

– Magnetically assisted induction

• Microwaves and Infrared

• Workforce development – education and training

6

Recent CHTE Projects

• A standard test for gas quench performance and

steel hardenability at slower cooling rates

• NDE for surface hardness and case depth

• Induction v. Furnace tempering• Induction v. Furnace tempering

• Life extension and cost reduction for furnace alloys,

baskets, fixtures, rollers

• Energy savings

• Upgrades to software – CarbTool, CarbonitrideTool

7

Heat Treatment Processes

TTTT 5. Aging/Tempering

2. Solutionizing/Austenization and/orSurface treating

t=t2 hr

TTTT

timetimetimetime

5. Aging/Tempering

3. Quenchingt=t5 hr

Room temperature

1. heating4. heating

Low pressure process versus

atmospheric treatments

• Low Pressure carburizing has been accepted in Europe due to

environments regulations and concerns

• In the USA the aerospace industry has nearly fully adopted

LPC but not high pressure gas quenching

• The US automotive industry is moving towards full adoption • The US automotive industry is moving towards full adoption

of LPC

• High Pressure Gas Quenching is lagging due to issues with

steel hardenability, residual stresses and distortion and new

alloy steels

• Asia?

9

Low temperature processes

(nitriding,..)

• Nitriding and ferritic carbonitriding use is

increasing to reduce residual stress and

distortion

– Surface treat through hardened alloys after – Surface treat through hardened alloys after

machining

• Low pressure surface treating is being

developed – nitriding – pulsed treatment?

• Plasma activation of the gas maybe useful?

10

Quenching : Gaseous: N2, He, H2 v. Liquid: oil and polymers• Issues:

– Safety

– Environmental regulations and concerns (OSHA and EPA in the USA)

– Performance

• Cooling rates – HTCs (T)

• Phase transformation kinetics

• Residual stress and distortion

• Surface cleanliness

• US industry slow to use

– LPC plus reheat and press quench?

– Critical parts?

11

Sintering processes : developing or not ?

• Process improvements for carburized steel

processes

12

3D-manufacturing of metallic

components : booming ?• YES - 3D processing is booming for metals and

some ceramics – media hype

– Aerospace is heavily invested

– Biomedical is investing

– Automotive is investing

• Issues

– Post processing of 3D printed metals needs

development – performance poorly understood?

– May only replace powder metal parts?

13

Industry Needs -1

• Automation and Robotics

– The Thermal Processing industry lags other industries in implementing these technologies

– Fork Lifts?

• Advanced Materials

– Fixtures, baskets, rollers and tubes – life and cost and energy

• Life extension by reduced oxidation and carburization resistance – alumina formers

• Ceramics and C-C composites

– Gas quenched parts need high hardenability

• New alloys like ferrium 63 being adopted

• Modeling and Simulation + Data

– US industry is slow to use the available models

– Slow to use model based controls

• Sensors and Controls

– Long lived sensors for atmosphere measurements

– Carbon flux sensors are needed for LPC

– The precision and accuracy needs to carefully defined

14

Industry Needs - 2

• Process Intensification

– Reduced cycle times – higher temperatures, grain growth issues?

– Single part flow - heat treat one part when needed

• Heat and Atmosphere Generation Methods

– Better burners

– Magnetically assisted induction – Magnetically assisted induction

• High magnetic fields enhance many processes

– Plasma atmosphere conditioning

• Microwaves and Infrared

– Rapid heating rates may reduce cycle times

• Workforce development – education and training

– Where will the future industry leaders come from?

– Education and training needs for shop floor, engineers and managers?

15

A few CHTE developments

• Nitriding – alloy specific Lehrer Diagrams

• Software for Carburizing and Carbonitriding

• Energy Savings via PHAST

• NDE for hardness and case depth• NDE for hardness and case depth

• Gas Quench Standards

16

� Previously only determined experimentally� Now using Thermo-Calc software, create for any steel

Nitriding Simulation

Lehrer diagram from literature1 (left) and created in Thermo-Calc (right) for pure Fe.

E. Lehrer, Z. Elektrochem. 1930

18

� KN vs. W(N) for set T-From Lehrer diagram & isopleth

� From KN in the process, Ns is obtained

� Constant KN defines Nc and Nd

Nitriding Simulation

hcp : εFe4N : γ’bcc : αfcc1: (Fe0.63Cr0.36)1(N,Va)1fcc2: (Cr0.57Fe0.25Mo0.16)1(N)1 Lehrer Diagram (top) and Isopleth (bottom) of AISI 4140

steel calculated using Thermo-Calc

�The compound layer growth kinetics obeys the parabolic law

25

30

AISI 4140, as-wash

T=550°C, Kn=8atm-1/2

Nitriding Simulation

y = - 5.5818+0.0658x

0

5

10

15

20

0 50 100 150 200 250 300 350 400 450

Co

mp

ou

nd

La

ye

r T

hic

kn

ess

(µµ µµm

)

Time1/2 (s1/2)

�Compound layer thickness is simulated based on parabolic law.�Dd=5x10-9cm2/s is adopted for diffusion zone�Dd is constant and only depends on the nitriding temperature

10

12

We

igh

t P

erc

en

tag

e o

f N

14hrs

30hrs

AISI 4140, as-wash

T=550°C, Kn=8atm-1/2

0.5

0.6

We

igh

t P

erc

en

tag

e o

f N

14hrs

Nitriding Simulation

0

2

4

6

8

10

0 20 40 60 80 100

We

igh

t P

erc

en

tag

e o

f N

Depth from Surface (µm)

45hrs

60hrs (predicted)

0

0.1

0.2

0.3

0.4

0.5

0 200 400 600 800 1000 1200 1400

We

igh

t P

erc

en

tag

e o

f N

Depth from Surface (µm)

30hrs

45hrs

60hrs (predicted)

Gas Nitriding

Tem

per

atu

re

Stage 2T2=548°C

t =50 hr

Stage 1T1=527°C

t1=10 hr

� Nitriding process

22

time

Tem

per

atu

re t2=50 hrt1=10 hr

dissociation rate:24-26%

dissociation rate:79-82%Room Temp

Gas Nitriding

� Nitrogen concentration and microhardness profiles

AISI 4140 AISI 1045

23

485

535

Mic

ro h

ard

ne

ss

HV

AISI 4140

360

380

400

Mic

ro h

ard

ne

ss H

V

AISI 1045

Gas Nitriding

� Microhardness vs %N

24

335

385

435

0.05 0.25 0.45 0.65 0.85

Mic

ro h

ard

ne

ss

HV

Nitrogen concentration wt%N

260

280

300

320

340

0.03 0.13 0.23 0.33 0.43 0.53

Mic

ro h

ard

ne

ss H

VNitrogen concentration wt%N

Gas carburizng

Temperature (°F) Carbon Potential Time (min) Simulation results

5120

1700 1.1 T1 Surface Carbon 0.8322

� Recipe of gas carburizing process

25

1

1700 0.85 T2 Case Depth (C=0.35wt%) (cm) 0.0889

1550 0.85 T3 Case Depth (C=0.35wt%) (in') 0.035

4320

1700 1.1 T1 Surface Carbon 0.6894

1700 0.7 T2 Case Depth (C=0.35wt%) (cm) 0.0887

1550 0.7 T3 Case Depth (C=0.35wt%) (in') 0.035

Gas carburizing

� Carbon concentration profiles

650

700

750

800

850

0.4

0.5

0.6

0.7

Mic

roh

ard

ne

ss H

V

Ca

rbo

n c

on

cen

tra

tio

n w

t%C

4320

Carbon Concentration

Microhardness

650

700

750

800

850

0.5

0.6

0.7

0.8

0.9

Mic

roh

ard

ne

ss H

V

Ca

rbo

n c

on

cen

tra

tio

n w

t%C

5120

Carbon Concentration

Microhardness

26

350

400

450

500

550

600

650

0

0.1

0.2

0.3

0.4

0 200 400 600 800 1000 1200M

icro

ha

rdn

ess

HV

Ca

rbo

n c

on

cen

tra

tio

n w

t%C

Depth µm

400

450

500

550

600

650

0

0.1

0.2

0.3

0.4

0.5

0 200 400 600 800 1000 1200 1400 1600

Mic

roh

ard

ne

ss H

V

Ca

rbo

n c

on

cen

tra

tio

n w

t%C

Depth µm

Specification Surface carbon: 0.70 ± 0.05 case depth: 0.889mm at C=0.35 wt. %

Carbon flux

(g/cm2/s)

1st Boost

(min)

1st Diffuse

(min)

2nd Boost

(min)

2nd Diffuse

(min)

Cooling

(min)

Hold

(min)

4320 1.09E-06 28 60 11 72 35 20

Specification Surface carbon: 0.80 ± 0.05 case depth: 0.889mm at C=0.35 wt. %

Vacuum carburizing

� Recipe of vacuum carburizing process

Specification Surface carbon: 0.80 ± 0.05 case depth: 0.889mm at C=0.35 wt. %

Carbon flux

(g/cm2/s)

1st Boost

(min)

1st Diffuse

(min)

2nd Boost

(min)

2nd Diffuse

(min)

Cooling

(min)

Hold

(min)

5120 5.36E-07 91 57 0.0 0.0 65 20

27

Vacuum carburizing

� Carbon concentration profiles

600

650

700

750

800

850

0.5

0.6

0.7

0.8

0.9

Mic

roh

ard

ne

ss H

V

Ca

rbo

n c

on

cen

tra

tio

n w

t%C

5120

Carbon Concentration

Microhardness

600

700

800

0.5

0.6

0.7

0.8

Mic

roh

ard

ne

ss H

V

Ca

rbo

n c

on

cen

tra

tio

n w

t%C

4320

Carbon Concentration

Microhardness

28

350

400

450

500

550

600

0

0.1

0.2

0.3

0.4

0.5

0 200 400 600 800 1000 1200 1400 1600

Mic

roh

ard

ne

ss H

V

Ca

rbo

n c

on

cen

tra

tio

n w

t%C

Depth µm

300

400

500

600

0

0.1

0.2

0.3

0.4

0 200 400 600 800 1000120014001600

Mic

roh

ard

ne

ss H

V

Ca

rbo

n c

on

cen

tra

tio

n w

t%C

Depth µm

650

700

750

800

Mic

roh

ard

ne

ssH

V

5120

630

680

Mic

roh

ard

ne

ssH

V

4320

Vacuum carburizing

� As quenched microhardness vs %C

29

y = 568.86x + 367.01

R² = 0.9682

450

500

550

600

650

0.2 0.4 0.6M

icro

ha

rdn

ess

Carbon concentration %C

y = 481.66x + 389.69

R² = 0.9973480

530

580

0.2 0.4 0.6

Mic

roh

ard

ne

ss

Carbon concentration %C

Energy Usage of Furnaces

30PHAST

Non-destructive Testing for Surface Hardness and Case Depth

Dec Dec 55thth, 2012, Worcester MA, 2012, Worcester MA

Lei Zhang, Mei Yang, Richard D. Sisson Jr. 31

Objective� Identify a hardness measurement technique that can

be applied accurately, rapidly and directly to parts, either non-destructively or with minimal invasiveness.

Objective and scope

32

Scope� Identify candidate nondestructive hardness

measurement techniques and experimentally evaluate the effectiveness.

700

800

900

1000

0.7

0.8

0.9

1

con

cen

trat

ion

/C%

Comparison of simulation and experimental results

for 1018 steel

Carbon concentrationCarbon simulationMicrohardness

�Carbon and microhardness profiles

Standard sample design

Mcr

oh

ard

nes

sH

V

33

0

100

200

300

400

500

600

700

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

Car

bo

n c

on

cen

trat

ion

/C%

Depth /mm

Mcr

oh

ard

nes

s

• Barkhausen noise• MWM• ACPD• Case Depth Detector

Electro magnetic properties

– Only conductive materials can be inspected

– Depth of penetration is limited– Surface finish and roughness

may interfere

NDT technology we apply

34

Hardness(case depth)

StressMicro-

structure

Gas Quench Standard

• Jominy – like test?

• Grossman tests?

– Characterize steels by a critical HTC

– Use simulations and experimental data– Use simulations and experimental data

35

Summary

• Interesting and exciting times for the thermal

process industry

– Optimized model based controls

– Single part flow– Single part flow

– Magnetically enhanced processes

– Plasma activated atmospheres

– NDE for hardness and case depth

– New materials

36