United States Steel
Automotive Solutions to Light Weighting
Generation 3 Steels - A Guide to
Applications of Gen3 AHSS
August 25, 2016
Michael Davenport
Director – Product Application Engineering
Introduction
Gen3
Characterization
Gen3 Guide
Summary
United States Steel Corporation
Why are Gen3 Steels Required?
“ The day of the passenger car made
primarily of iron and steel is on the wane”
giving ground to aluminum, magnesium
and plastics.
Introduction
Gen3
Characterization
Gen3 Guide
Summary
United States Steel Corporation
2
What is the Automotive Material of Choice?
CARS Magazine
October 1953
“ The day of the passenger car
made primarily of iron and steel is
on the wane” giving ground to
aluminum, magnesium and
plastics.
Introduction
Gen3
Characterization
Gen3 Guide
Summary
United States Steel Corporation
3
Steel Innovation
1970s – Body-on-Frame
Body-Frame-Integral
1980s – Uncoated
Galvanized Rust Resistant
1990s – Mild Steel
High Strength and Bake Hard
Steel
“ The day of the passenger car
made primarily of iron and steel is
on the wane” giving ground to
aluminum, magnesium and
plastics.
2000s – Mild & High Strength
GEN1 AHSS and PHS
Today – GEN3 Advanced High Strength Steels
Introduction
Gen3
Characterization
Gen3 Guide
Summary
United States Steel Corporation
4
What is Gen3?
70
Generation 2
60
UTS x TE =
25000
Elongation (%)
50
IF
IF - HS
40
Mild
30
ISO
BH
20
HSL
A
10
MART
Generation 1
0
300
0
600
900
1200
1600
Tensile Strength (MPa)
USS CR 1180 Gen 3 Target
Introduction
Gen3
Characterization
Gen3 Guide
Summary
United States Steel Corporation
5
Data Needed to Turn Coils into Parts
Microstructure – EBSD Image Quality Map
Bake
hardening /
Aging
High strain rate
ture
nite, and
Gauge and width
capability
ght gray
Denise,
Janet, Kyle &
Stephanie
Mechanical
Properties
Microstructure Characterization
CONFIDENTIAL - United States Steel Corporation
Your case studies and
template designs are
beautiful and central
to this book.
5
Fatigue
1.0
True Major Strain
Plane Strain
0.5
Forming Limit
Curve
Aisling, Denise,
Tyler & Ivan
The book wouldn’t have
happened without your
rocking design skills and
tenacity.
Safe
Compatibility with paint system
-0.5
0
True Minor Strain
0.5
FLD
Hole expansion
ratio
Dynamic
Crush
Spot Weld
Dynamic
Bending
Introduction
Hydrogen
embrittlement
Gen3
Characterization
Gen3 Guide
Summary
Fracture toughness
evaluation
United States Steel Corporation
6
Mechanical Properties – Formability and High Strength
66% Higher Strength
25% Shorter crush distance
1200
300
250
800
Crush Force (kN)
Engineering Stress [MPa]
1000
600
400
USS: 590MPa
USS: Gen3 980MPa
200
DP590 (1.6mm)
200
980Gen3 (1.0mm)
150
100
50
0
0
0
5
10
15
20
Engineering Strain (%)
25
0
50
100
150
200
Displacement (mm)
250
300
980 Gen3 make 37% weight save and better crush performance possible
Introduction
Gen3
Characterization
Gen3 Guide
Summary
United States Steel Corporation
7
Mechanical Properties – Formability and High Strength
5% Higher formability with 980 Gen3
DP590
70
980GEN3
0.2
True Thinning Strain
65
Cup Height at Fracture (mm)
Uniform strain distribution with 980 Gen3
0.1
60
DP590
980 Gen3
0
55
DP590
980GEN3
0
20
40
Distance (mm)
60
980 Gen3 has 5% higher formability and better strain distribution than DP590
Introduction
Gen3
Characterization
Gen3 Guide
Summary
United States Steel Corporation
8
Welding 980Gen3 - Characterization of Parameters
No softening in HAZ observed
Wide range of welding parameters
19
600
D
2.2 kAmp
A
17
500
16
B
Hardness, HVN
Weld Time, Cycles
18
E
2.1 kAmp
400
15
14
F
2.2 kAmp
C
300
13
6
7
8
9
10
Weld Current, kAmp
200
0
10
20
30
Indentation
40
50
Welding 980Gen3 steels can be achieved with a wide range of welding parameters and uniform hardness behavior.
Introduction
Gen3
Characterization
Gen3 Guide
Summary
United States Steel Corporation
9
Dynamic Crush – Critical for Energy Absorption
Part Testing
Structural Analysis
Energy absorption (kJ)
20
15
10
Test 1
5
Test 2
Simulation
0
0
Part correlation
Introduction
Gen3
Characterization
50
100
150
Displacement (mm)
200
Test/Simulation correlation
Gen3 Guide
Summary
United States Steel Corporation
10
Guide to Applications of Gen3
Global
Formability
Material
Portfolio
Forming
Local
Formability
Functional
Objectives
Assembly
Impact
Crack
Resistance
Structural
Components
Introduction
Gen3
Characterization
Gen3 Guide
Summary
United States Steel Corporation
11
Material Portfolio – Hance Diagram View
Introduction
Gen3
Characterization
Gen3 Guide
Summary
United States Steel Corporation
12
Understand the Components Functional Objectives
q Functional Objective
§  Form into complex shapes
§  Minimize Intrusion
§  Absorb Energy
q  Application
§  Load beam reinforcements
§  B Pillar reinforcements
§  Roof rail inner reinforcements
§  Front Roof Header & Bow roof
§  Panel Body side sill reinforcements
§  Reinforcement Front & Rear rails
§  Reinforcement floor cross members
Introduction
Gen3
Characterization
Gen3 Guide
Summary
United States Steel Corporation
13
Understand Global Formability
Splits in 780MPa UTS
Result with USS solution:
•  Safe forming with upgrade &
downgage
•  Good correlation between CAE and
trial
•  13% weight reduction
Splits
•  Minimal springback without any
adjustment to production die
980 Gen3 for global formability
Safe
Introduction
Gen3
Characterization
Gen3 Guide
Summary
United States Steel Corporation
14
Understand Local Formability – Edge Stretch & TFS
980MPa UTS selected by
strength only
Result with USS solution:
•  Safe Forming
•  Improved crack resistance
Splits
980MPa UTS selected by
microstructure and TFS
Safe
Introduction
Gen3
Characterization
Gen3 Guide
Summary
United States Steel Corporation
15
Local Formability - Bending Under Tension & TFS
Determination of minimum die radius
Future Paper
Introduction
Gen3
Characterization
Gen3 Guide
Summary
United States Steel Corporation
16
Local Formability - Crack Propagation & TFS
Future Paper
Introduction
Gen3
Characterization
Gen3 Guide
Summary
United States Steel Corporation
17
Local Formability - Crack Propagation & TFS
Future Paper
Introduction
Gen3
Characterization
Gen3 Guide
Summary
United States Steel Corporation
18
Guide to Applications of Gen3
Forming
Material Portfolio
Functional Objectives
• Form into complex
shapes
• Minimize Intrusion
• Absorb Energy
Assembly
Impact
Structural Component
Introduction
Gen3
Characterization
Gen3 Guide
Summary
Global Formability
Local Formability
Crack Resistance
United States Steel Corporation
19
Full Engineering Solution Provider
Introduction
Gen3
Characterization
Gen3 Guide
Summary
United States Steel Corporation
20