MATERIALS & PROCESS DESIGN FOR HIGH TEMPERATURE CARBURIZINGIntegrating Processing & Performance

Goal: Integrate model-based robust control of the HTC with concurrent design of novel HTC steels for higher performance and processability

Challenge: Need mechanistic model to achieve robust control and performance Data to validate optimal processing

Benefits: 10X reduction in process cycle time, reduces scrap from quench distortion, enhanced performance through optimized steels, broader applications through deeper cases.

FY05 Activities: Robust application of new process model, demonstrate enhanced performance.

Participants:WPI (CHTE)NU (SRG)Midwest Thermal-VacGMQuesTek Innovations

Barrier-Pathway Approach

Barriers• Lack of industry

process control

• Lack of optimized steels

• Limited performance data

• Limited applications

Pathways• Mechanistic process

model for robust control

• Concurrent materials & process design (including final surface treatment)

• Industry test program

• Deeper cases

Critical Metrics• Acceptable part-to-part

variability (H, %C)

• Enhanced case hardness, residual stress, grain coarsening resistance, hardenability (reduced distortion)

• Fatigue Strength(single-tooth, RCF)

• New markets(camshafts, tool & die)

MATERIALS & PROCESS DESIGN FOR HIGH TEMPERATURE CARBURIZINGIntegrating Processing & Performance

MATERIALS & PROCESS DESIGN FOR HIGH TEMPERATURE CARBURIZINGIntegrating Processing & Performance

AIM Technology Acceleration

Higher Performance Energy Efficient Powertrain

Reduced Scrap (Eliminate Quench Distortion)

Process Energy Savings – 20 trillion BTU/Yr

CycleTime Reduction – 10X

Benefits (est.)

Gas Carburizing vs. Vacuum Carburizing

Limited by saturation of Austenite or formation of continuous filmsFaster (higher carbon potential/temp)More homogeneousVery predictable and reproducible

Surf

ace

carb

on c

onte

nt

0.85

1.0

0.2

%C

Time

Hold

Diffuse

Gas

0.85

1.0

0.2

%C

Time

Boost Intermediate diffuse

Final diffuse

Vacuum

Limited by soot formation

Midwest Thermal Vac

Features of Vacuum Carburizingand Capabilities of Software in Use

1) Diffusivity, D(C,T), varies with C content and time

2) Flux, J(t), varies with time

3) Carbide formation and dissolution

4) Multiple phase diffusion process (only after continuous film formation)

Simple 1-D:D(T)

J=constant

DICTRA 1-DD(C,T)

J(t)

Carbide formation and dissolution

Multiple phase diffusion

DEFORM 2D/3DD(C,T)

J (t)

Weight Gain and Surface Carbon Measurement for C61

Large enough surface area required for accurate weight gain measurement (for average or instant flux calculation)

Too long boost → carbide formation

Too long boost → retained austenite and plate martensite

Phases and Morphology after Long Boost for C69

Carbides on grain boundaries and left surfaceRetained austenite in casePlate shape martensite in case

5 um

20 um

Simulated Carbon and Measured Hardness Profile for C61

5 0 0

5 5 0

6 0 0

6 5 0

7 0 0

7 5 0

0 .0 0 0 0 .0 1 0 0 .0 2 0 0 .0 3 0 0 . 0 4 0 0 . 0 5 0 0 .0 6 0 0 .0 7 0 0 .0 8 0

Vick

ers

Har

dnes

s [H

V 50

0 g]

D e p t h f r o m S u r f a c e [ in c h ]

Simple 1D simulation

Real profile

Sur

face

C (w

t%)

DEFORM 3D Simulation for C61 Carburized at 950C

Boost + short diffuseDepth: ~ 139umSurface Hardness: ~ HRC 58

Boost onlyDepth: ~ 110umSurface Hardness: ~HRC 65

Corner effect:High C potential of the gasCan even be induced in diffuse cycles with low C potential

GUI of Versatile and Multi-constraint Software

GUI of Versatile and Multi-constraint Software

Challenge:When to start a final diffuse trialDICTRA workspace management (for rollback or different final diffuse trials)Exportation from workspaceFile management (plotting for different final diffuse trials)

Toughest challenge: implement all these flexibilities and constraints into one code

Case Study (1mm Depth)

Surface C

(max: 3 wt%)

Total C in region

Case Study (1mm Depth)

C profileDesired Surface C: 0.55 wt%

Desired Case Depth: 1mm

Desired C at Case Depth: 0.14 wt%

14

ARCHITECTURE DESIGNARCHITECTURE DESIGN

KBE

Work Flow

Analysis

Information Repository

LSF/Java

Geometric Modeling

Structural Modeling

Thermal Modeling

Gamma Prime Model

Microsoft Excel

Gamma Prime Model

PrecipiCalc

eMatrix

Oracle

Microsoft Access

Analysis Components

Models provided by Pratt & Whitney, General Electric, Questek, and others. Integrated by Engineous into the DKB architecture via iSIGHT

DRM *Java/HTML

Exploration Tech.

* Distributed Resource Management

Networking

3RD Party tools to extend iSIGHT’s integration capabilities

Integration Infrastructure

Core Utilities

iSIGHT framework provided by Engineous Software

Documentum

Effect of Surface Treatments on Residual Stress

0

200

400

600

800

1000

1200

1400

1600

Laser Peened482C Temper200C TemperLN

-σsu

rface

(MP

a)

Treatments

C69 Full Cycle Carburization

C61 C69

Peening processes allow us to achieve -1.2 GPa, ~-1.5 GParesidual stresses on the surface of C61, C69, respectively.

*Data Courtesy: B. Tiemens

1 2 3 40

200

400

600

800

1000

1200

1400

1600

SurfaceMaxium

Shot peenedTemperedstage IV

TemperedStage I

Quenched

-σsu

rface

(MP

a)

Effects of Surface Treatments

IN 718, Zhuang & Halford, International Journal of Fatigue, 2001 (23), S31

On Residual Stress

Res

idua

l Stre

ss (M

Pa)

Distance from surface (um)

Res

idua

l Stre

ss (M

Pa)

4340 steel sheet with both sides laser peened. The mid-thickness of the sheet is at 0.75mm

C69 LPC61 SP

Pyrowear53 SP

Pyrowear53 LP

Surface Optical Image after Peening

100µm

100µm

100µm

100µm

Surface Residual Stresses in Materials

0 100 200 300 400 500 600 700 800 9000

200

400

600

800

1000

1200

1400

1600

1800

2000

4340 Laser Peened

unpeened

720

C61 SPMaxSurface

C61

AISI 4140shot peened

C69

M50 M50NiLAISI 52100

AISI 4340

-σsu

rface

(MP

a)

Surface Hardness (VHN)

Pyrowear53 SP

Pyrowear53 LP

C69 LP 1.5GPa

1.0GPa

APS Experiment

E ~ 80 keV

Conical Slit

3D Probe of Strain/Stress

Conical Slit 2D Detector

C69

Ultimate Bending Strength

Displacement (mm)

0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00

Appr

oxim

ate

Ben

ding

Str

ess

(MPa

)

0

1000

2000

3000

4000

5000

Appl

ied

Tens

ile L

oad

(N)

0

2e+4

4e+4

6e+4

8e+4

1e+5

Premium Steel

C69

Single Tooth Bending Fatigue Performance

log (Cycles)

3 4 5 6 7

Max

imum

App

lied

Tens

ile S

tres

s (M

Pa)

1000

1200

1400

1600

1800

2000

2200

Premium SteelC69

Baseline Steel

C61

Ultimate Bending Strength

Displacement (mm)

0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00

Appl

ied

Tens

ile L

oad

(N)

0

2e+4

4e+4

6e+4

8e+4

1e+5

Appr

oxim

ate

Ben

ding

Str

ess

(MPa

)

0

1000

2000

3000

4000

5000C61-'04

C61-'03

Premium Steel

Single Tooth Bending Fatigue Performance

log (Cycles)

3 4 5 6 7

Max

imum

App

lied

Tens

ile S

tres

s (M

Pa)

1000

1200

1400

1600

1800

2000

2200C61 - '04

Premium Steel

C61 - '03

Baseline Steel

Role of LoadSurface Residual Stress of Fatigue Tracks

Fatigue TrackNon-fatigue trackMaterial

823±4Relaxation: -42%

1085±6Relaxation: -23%

1410±31418±33Pyrowear53, LP

756±3Relaxation: -20%

?1569±7946±21119±5Pyrowear53, SP

Hoop (MPa)Axial (MPa)Hoop (MPa)

Axial (MPa)

Residual stress relaxation of laser peened material is greater than that of shot peened material.

ID Number

Task / Milestone Description Planned Completion

Actual Completion

Comments

1a ThermoCalc Modeling 7/31/05 90% 1b Process Experiments 7/31/05 80% 1c Industrial Experiments 7/31/05 35% 1d Hardenability 10/31/03 10% 2a Redesign Alloys 10/31/04 60% 2b Grain Stability 10/31/04 60% 3a RCF and Wear 7/31/05 50% 3b Residual Stress 7/31/05 35% 3c Redesign for Performance 7/31/05 30% 3d Forming Dies 7/31/05 20% 3e Forging/Casting Dies 7/31/05 0%

Microstructural Design Example: C69• Gears

– 0.015” to 0.050” case– 0.040” typical

• Camshafts– 0.100” typical

50

52

54

56

58

60

62

64

66

68

0 0.02 0.04 0.06 0.08 0.1 0.12Case Depth (inches)

Roc

kwel

l Har

dnes

s

50

52

54

56

58

60

62

64

66

68

0 0.02 0.04 0.06 0.08 0.1 0.12

Case Depth (inches)

Roc

kwel

l Har

dnes

s

Current Sales Ferrium® C61

CamshaftsRing and Pinion

Commercialization History of Carburized Alloys

• Product Sales– Ring and Pinion– Camshafts

• Application Trials– Gears

• Racing• Aerospace• Helicopter• Marine

– Dog Rings (racing)– Input Shafts (racing)– Roll Forms– Cutlery– Skate Blades

• Markets Surveyed– Ball Screws

– Tool and Die

– Golf Clubs

Materials to be studied at WPI

• 8160 gears -- GM• 5120 gears -- GM• 8620 shafts -- Deere• SAE 4118/4122 -- CAT• SAE 9310 -- CAT• Fe-Mo-Ni (P/M)-- Hoeganaes Corp.• Fe-Cr-Mn-Mo (P/M) -- Hoeganaes Corp.

Carburization trial will be conducted at Surface Combustion,OH, using their low pressure carburizing facilities.

FY05 (Y4) Plans

•AIM / iSIGHT robust process design

•Residual stress optimization of C69

•Performance testing of PM-C69Ti

•Prototype characterization of new LC alloys

•Quantify CCT

•Expand deep case applications (cams; tool & die)

•CHTE dissemination of process control (vendors & steels)