Transcript Introduction to Hot Stamping and Trends

Introduction to Hot Stamping and Trends
By
Dr. Eren Billur, Post-doctoral Researcher
and
Dr. Taylan Altan, Director and Professor
Presented at ESI Hot Forming Die Engineering Seminar
October 15th, 2013
Center for Precision Forming (CPF)
www.cpforming.org / www.ercnsm.org
© Copyright Center for Precision Forming (CPF). All Rights Reserved.
Center for Precision Forming - CPF
CPF is supported by NSF and 16 member
companies, interested in metal forming.
Interlaken
Technology Corporation
IMRA
2
CPF – Current Projects
• Material Characterization
• Friction / Lubrication
• Process Simulation / Forming Al & AHSS
• Die Wear in Forming AHSS
• Edge Quality in Blanking / Shearing
• Hot Stamping of UHSS
• Servo Drive Presses and Hydraulic Cushions
3
Sponsors & Partners of Hot Stamping Research
Interlaken
Technology Corporation
TSG
IMRA
Tooling Systems
Group
4
Crashworthiness
Crumple Zone
Passenger Zone
Crumple Zone
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Images from: media.Daimler.com
Crashworthiness
Passenger Zone
Roof rail
Crumple Zone
A-pillars
B-pillars
Door beams
Intrusion Resistance
Ultra High Strength
Absorbing Energy
High Strength + Elongation
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Ref: Hilfrich 2008.
Summary of Hot Stamping
Mild Steels
70
L-IP
Conventional High
Strength Steels
Better Formability
Total Elongation (%)
60
50
40
30
20
Aust.
SS
IF
TWIP
Advanced High
Strength Steels
Mild
BH
Al
CMn
2nd Generation
AHSS
Higher Press Forces
TRIP
Al
Aluminum Alloys
(hs)
10
0
MART
0
200
400
600
800
1000 1200 1400
Ultimate Tensile Strength (MPa)
1600
1800
2000
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Summary of Hot Stamping
Mild Steels
70
L-IP
Conventional High
Strength Steels
Total Elongation (%)
60
50
Aust.
SS
IF
40
BH
CMn
2nd Generation
AHSS
Al
Al
20
(hs)
10
0
Advanced High
Strength Steels
Lightweight Potential for
Intrusion Resistance
Mild
30
TWIP
Higher Springback
Aluminum Alloys
MART
0
25
50
75
100
125
150
175
3
Specific Strength (MPa/(k g/m ))
200
225
250
8
Summary of Hot Stamping
Heated >950 C
Austenite
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Indirect Process:
2
Total Elongation (%)
60
50
IF
3-5 min.s
Mild in Furnace
40
TWIP
Quenched in the die
>27 C/s
Direct Process:
BH
30
CMn
20
Mn-B Alloyed steel
(as delivered)
Ferrite & Pearlite
10
0
Aust.
SS
0
200
400
1
TRIP
Quenched
Martensite
MART
600
800
1000 1200 1400
Ultimate Tensile Strength (MPa)
1600
1800
2000
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Hot Stamping - Trends
Mass % of hot stamped
steel in BIW
Audi
A3
Volvo
XC90
SAAB
9000
VW
Passat
19%
1984
≈
7%
2003
Volvo
XC90
44%
Volvo
26%
V40
VW
Golf VII
28%
20%
2006
2012
2014
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Ref: Lund 2009, Holzkamp 2011, Lindh 2011, Bielz 2012, Mattsson 2012, VW Media Services.
Hot Stamping - Trends
Parts per year (in millions)
550
500
450
400
350
300
250
200
150
100
50
0
>20
Parts/
Vehicle
8-10
Parts/
Vehicle
6 Parts/
Vehicle
450 million
per year
(2013)
4 Parts/
Vehicle
3 million
per year
(1987)
1987
Ref: Oldenburg 2010, Hund 2011.
95 million
per year
(2007)
8 million
per year
(1997)
1997
Year
210+ lines
around the world
+55 planned
2007 ’08 ’09 ’10 ’11 ’12 ’13 11
Hot Stamping - Trends
Passenger
Zone
Deformation
Zone
(a) Front view
before crash
(b) Side view
after crash
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Ref: Macek 2006, Image from: IIHS.
Hot Stamping - Trends
22MnB5
1500 MPa
(215 ksi)
HSLA 340
(50 ksi)
Tailor Rolled Blanks Tailor Welded Blanks
Ref: Rehse 2006, Hilfrich 2008, Lee 2012, Images from: IIHS, VW Media Services.
Tailored Hot
Stamping
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Hot Stamping - Trends
550 C
Tailored Heating
(Austenitizing)
20 C
Tailored Quenching
Ref: Breidenbach 2009, Hedegärd 2011, Süß 2011, Steinhoff 2013. Image from: IIHS.
Post Tempering
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Hot Stamping - Trends
900
800
Temperature ( C)
700
A+F
600
A+P
500
400
A+B
Ms
A+M
300
Mf
200
100
Time to cool (s)
Cooling Rate ( C/s)
Hardness (HV)
8
100
475
27 40 80 133 266
3
30 20 10 6
474 417 278 232 182
1143
0.7
163
4000
0.2
150
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Finite Element Simulation of Hot Stamping
Our simulations aim to predict the final properties of hot
stamped components:
1) Presence of defects: cracks, wrinkles or local necking,
2) Hardness distribution (both in uniform and in tailored parts),
3) Cooling channel analysis,
4) Distortion of the final part.
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Finite Element Simulation of Hot Stamping
Fluid Mechanics
Heat generation due to
plastic deformation.
Mechanical Field
- Mechanical material
properties,
- Volume change due
to phase
transformation.
Thermal expansion.
Phase
Microstructure
transformation
depends on
depends on
temperature.
stress and strain.
Heat transfer to the
coolant medium.
Thermal Field
- Thermal material
properties,
- Latent heat due to
phase
transformation.
Microstructure Evolution
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Ref: Åkerström 2006, Porzner 2012.
Finite Element Simulation of Hot Stamping
Only needed in tailored parts
Gravity
Holding
Forming
Die Quenching
Springback
Air
Quenching
Mechanical
Thermal +
Mechanical
Thermal +
Mechanical
Thermal + Metallurgical
Mechanical
Thermal +
Metallurgical
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Predicting Defects
Crack prediction in a Side Member Reinforcement
Colors other than gray:
Thinning >20%.
Part stamped at the participating
company
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Predicting Defects
Die Segment 1
Die Segment 2
Die Segment 3
Blank (Ti = 850 C)
Heated Dies (Ti = 450 C)
Cooled Dies (Ti = 20 C)
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Predicting Defects
Crack / wrinkle prediction in a tailored part
With one-piece blankholder
With two-piece blankholder
15 kN
20 kN
5 kN
Crack
Wrinkles in
the soft area
Non-symmetric
draw-in
No wrinkles or
cracks
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Hardness Distribution
Die Quenching Optimization
Martensite phase fraction
1.00
0.85
0.71
0.57
0.42
0.28
0.14
0.00
Min =
Max =
0.00
1.00
4 seconds die quenching
10 seconds die quenching
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Hardness Distribution
Heat Transfer Coefficient (W/m 2C)
100
140
Air Quenching Stage
Maximum Austenite (%)
Convection
120
80
100
60
80
60
40
40
20
20
0
Ref: Shapiro 2009.
Radiation
0
10 20020
400 40 600
30
50
Temperature
Time (s) (C)
60800 70
1000
80 23
Hardness Distribution
Results
Soft zone:
310 – 330 HV
920 – 1020 MPa
(~135 – 150 ksi)
Literature:
[George 2011] , 400°C dies = 790-840 MPa
[Feuser 2011], 450°C dies = ~850 MPa
Hardened zone:
485 – 515 HV
1500 – 1590 MPa
(~220 – 230 ksi)
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Cooling Channel Analysis
Cooling channel performance
1.3 mm 22MnB5 “roof rail”
Mass produced for a European car.
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Cooling Channel Analysis
Cooling channel performance – tailored part
1.2 mm 22MnB5 “B-pillar”
1605
300
925
920
1595
915
1589.4 MPa
1590
910
1590.3 MPa
1585
905
250
Temperature ( C)
1600
Minimum UTS (MPa)
Maximum UTS (MPa)
921.4 MPa
Max
219 C
200
150
100
50
Min
20 C
903.8 MPa
1580
900
1
2
3
4
5
6
Part # (Cycle)
7
8
9
10
0
0
20
40
60
80
Time (s)
100
120
140
160
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Distortion Analysis
Ongoing work: Distortion in Tailored Parts
stra in
au steni tisati on
0.0 15
0.0 1
ma rten sitic
tra nsformati on
+Initial,
undistorted grid
0.0 05
+Interstitial dissolved
carbon
0
+ carbon, tetragonal distorted
grid
200
-0.0 05
Ref: Porzner 2012.
Material 1
400
600
800
100 0
120 0
Material 2
temperatu re
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Summary and Conclusions
Several case studies were used to develop, calibrate and
validate material models, conversion factors and methods to
predict:
1)
2)
3)
4)
Defects (cracks, wrinkles, local necks),
Vickers hardness, yield and ultimate tensile strengths,
Cooling channel / heating cartridge performance,
Distortion in a non-uniform part.
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What is next?
1) New materials with
High Strength (USIBOR 2000, even higher strength:
MBW1900, HPF 2000)
More lightweight potential
and increased
productivity.
22MnB5 (USIBOR 1500,
MBW1500, HPF1470)
2) New coatings: better
corrosion properties and
friction conditions.
Engineering Stress (MPa)
2000
1500
1000
500
High Elongation (DUCTIBOR 500,
MBW500)
0
0
5
10
Engineering Strain (%)
Ref: Lanzerath 2011, Vietoris 2011, Ferkel 2012, Lee 2012.
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3) New heating, forming
and quenching methods
to improve productivity.
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Competition: DP, TRIP, TWIP, and
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3gAHS Steels with high YS and UTS.
Deliverables / Hot Stamping
As of September 2013:
- 15 CPF Reports (Literature review and FE simulations),
(5 in the last 6 months) [confidential to members],
- 6 Stamping Journal R&D Updates
(+1 more in progress),
- 6 Conference Proceedings (+1 more submitted),
- 1 Book Chapter in “Sheet Metal Forming: Vol 2:
Processes and Applications”, (see next slide),
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- And a new “Hot Stamping” book in progress!
Questions / Comments?
For more information , please contact:
Dr. Eren Billur ([email protected]), Ph 614-292-1785
Dr. Taylan Altan ([email protected]), Ph-614-292-5063
Center for Precision Forming –CPF (www.cpforming.org)
339 Baker Systems,1971 Neil Ave,
Columbus, OH-43210
Non-proprietary information can be found at web sites:
www.cpforming.org
www.ercnsm.org
References can be sent upon request.
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