Physical Simulation of the

Thermo-Mechanical Rolling

Process

Blake M. Whitley

bwhitley@mines.edu

Date: May 14, 2015

Advisor: John G. Speer

Group: Bar and Forging Steels, ASPPRC

Colorado School of Mines

Colorado School of Mines

Golden, Colorado

ASPPRC:

An Industry-University

Cooperative Research Center

Established 1984

Advanced Steel

Processing and

Products

Research Center

(ASPPRC)

Concentrate on research at the interface

between producers and users of steel

ASPPRC Participants: May 2015

Steel Producers AK Steel

ArcelorMittal Steel

Baosteel

CSN

Evraz Inc., N.A.

Gerdau

Kobe Steel

Nucor Steel Co.

POSCO

SABIC

SSAB Enterprises, LLC

Tata Steel Europe

Ternium

TimkenSteel

TMK IPSCO

United States Steel

voestalpine Stahl GmbH

Heavy Equipment Mfg. Caterpillar Inc.

Deere & Co.

Automotive Manufactures Fiat Chrysler Automobiles

Ford Motor Co.

General Motors Co.

Suppliers Bekaert

Johnson Controls

Other Chevron Energy

CBMM N.A. (Niobium)

Evraz Stratcor (Vanadium)

Los Alamos National Lab

Precision Castparts Corp.

ASPPRC 1990

ASPPRC Sponsor Locations (2015)

Many international facilities of corporate participants not shown

8

Gleeble® 3500

Capabilities:

• Heating rates of 10,000 ºC/s

• Quench with compressed

gas or pressurized water

• Up to 10 tons of force

• Displacement rates up to

1,000 mm/s

Ideal for:

• Hot Tension/Compression

• Casting/Solidification Studies

• Dilatometry

• Forging Studies

• Weld HAZ Simulation

• Hot Rolling Simulation

Bar Rolling Mill Schematic

Reheat

Furnace Roughing Mill Cooling

Section Reducing Block

Precision Sizing

Block

T~1200 ºC T~1100 ºC T~800-1000 ºC T~800-1000 ºC

3

1045 Al (HR & TMP)

10V45 (HR & TMP)

10V45 Nb (HR & TMP)

2” Bars

Industrial Bars

*Based on mill data from the Gerdau, Monroe bar mill. (2012)

10

Experimental Plan- Torsion Variables

Rolling Pass Area (mm2) Strain (reduction in area)

Initial 22500

Roughing R1 17825 0.20778

R2 13225 0.25806

R3 9500 0.28166

R4 6793 0.28495

R5 5000 0.26395

R6 3848 0.23040

R7 (dummy) 3848 0.00000

T~1050-1100C R8 (dummy) 3848 0.00000

Waterbox

3848

Reducing RB1 (dummy) 3848 0.00000

Block RB2 (dummy) 3848 0.00000

RB3 2734 0.28950

RB4 1964 0.28164

RB5 1524 0.22403

RB6 1452 0.04724

RB7 1385 0.04614

RB8 1340 0.03249

Te

mp

era

ture

(ºC

)

1300

1200

1100

1000

900

800

700

600

500

400

300

200

100

0

Distance from Reheat Furnace (m)

0 200 20 40 60 80 100 120 140 160 180

HR

Roughin

g

Center

Mid-radius

Surface

5

Te

mp

era

ture

(ºC

)

1300

1200

1100

1000

900

800

700

600

500

400

300

200

100

0

Distance from Reheat Furnace (m)

0 200 20 40 60 80 100 120 140 160 180

Fin

ishin

g

& S

izin

g

Waterbox

Cooling

Center

Mid-radius

Surface

TMP

6

13

1045 Al 10V45 10V45 Nb

HR

TMP

*All images taken at bar surfaces

100 μm 100 μm

100 μm

100 μm

100 μm 100 μm

Characterization of As-Received Bars (Gerdau-Monroe)

Bar Rolling Mill Schematic

8

10V45 Nb

Experimental Alloys

15

Alloy C Mn Si Ni Cr Mo Ti

1045 Al 0.45 0.72 0.24 0.08 0.12 0.04 0.001

10V45 0.45 0.82 0.28 0.07 0.15 0.03 0.001

10V45 w/ Nb 0.46 0.85 0.2 0.08 0.14 0.03 0.001

Alloy Nb V Al N S P Cu

1045 Al 0.001 0.003 0.021 0.0097 0.025 0.010 0.13

10V45 0.001 0.089 0.000 0.0127 0.027 0.011 0.15

10V45 w/ Nb 0.020 0.092 0.000 0.0124 0.030 0.018 0.16

1045 base steel with 3 microalloying variations:

16 C. M. S. G J Richardson, D N Hawkins, Worked Examples in Metalworking. London: The Institute of Metals, 1985.

3

*aa

**

aa

= equivalent true strain

= shear strain

= effective radius, 0.724*radius

= angle of twist

= gauge length

*a

*a

a

How to Simulate Industrial Bar Rolling?

Time-Temp Profiles

Tem

pera

ture

Time

6 Roughing Passes at 1200 ºC

Total Shear Strain = 3.13

6 Finishing Passes

Total Shear Strain = 2.05

Tnr

HR

TMP

21

7

18

Equivalent True Stress-Strain

•For a subsize 1045 Al

torsion specimen

deformed under

conventional rolling

conditions (1000 ºC

finishing).

•Hardening observed

during roughing steps.

•Combination of hardening

and softening observed

during finishing steps.

1200 ºC

1000 ºC

19

Peak-Torque at each Pass

Peak Torques per Pass

•Composite effects –Strain hardening

–Dynamic recrystallization

•Two Processing

Conditions –Conventional finishing

–TMP finishing

•Three Chemistries –1045 Al

–10V45

–10V45 Nb

HR

1045 Al

10V45

10V45 Nb

10V45

1045 Al

10V45 Nb

TMP (800 ºC)

HR (1000 ºC) Roughing (1200 ºC)

20

1200 ºC

1000 ºC

800 ºC

Peak-Torque at each Pass

HR

HR

HR

21

Time-Temperature Rolling Profile

(Gleeble Torsion)

Surface Temperature

•Thermal Processing –Austenitized at 1200 ºC for

20 minutes

–Roughing deformations

–Air-cooling simulation to

1000 ºC

•Two Processing

Conditions –Conventional finishing

–TMP finishing

*Measured by optical pyrometer

Hot

22

10V45

Hot Roll

air cool

TMP

air cool

Microstructural Characterization of

Torsion Specimens

Hot Roll

N2 quench

23

TMP

Air Cool

Microstructural Variation Across

Torsion Specimens

Surface Effective Radius Center

1 mm 10V45

24

Microstructural Characterization of

Torsion Specimens- 1045 Al

HR + Air Cool HR + Quench

Surface

TMP + Air Cool

Effective

Radius, r*

Center

Austenite Deformation in Tension

25

(a) (b) (c) (d)

• Normal strains,

typical of

industrial bar

rolling

• Linear strain paths

• Minimal strain

gradients

**In collaboration with A. Araujo, ASPPRC

Austenite Deformation in Shear

26

(a) (b) (c) (d)

• Shear strains,

such as those

employed during

torsion

simulations

• Nonlinear strain

paths

• Defined strain

gradients (radially)

**In collaboration with A. Araujo, ASPPRC

27

Prior Austenite Grain Size (PAGS)

A

C

B

10V45 Nb

A B

C

28

PAGS Assessment

1045 Al 10V45

Austenitized

(1200 °C)

10V45 Nb

Hot Rolled

TMP Rolled

1045 Al

Other Alloys after TMP, Quench, PAGs

10V45 Nb

29 10V45

30

Physical Simulation of the Thermo-Mechanical

Rolling Process

Blake M. Whitley

bwhitley@mines.edu

Thanks for your attention!

Advanced Steel Processing & Products Research Center (ASPPRC)