Current Light-weighting technologies
on Aluminum alloys for Automotive body structures

Dr. Tadashi Aiura
KOBE STEEL, Ltd.
1
T. Aiura, Aluminium 2014 Conference, 08 October 2014.

Contents
The background on light weighing requirementsof automotive body structures
Light weighting technologies of Closure Panels
by Aluminum Alloy
Advantages of Aluminum on Closure panel applications
Effect of additive on high paint bake response of 6xxx alloy.
Forming & Joining technologies

Prospects on aluminum alloy applications
for light weight Automotive bodies in the future

2
T. Aiura, Aluminium 2014 Conference, 08 October 2014.

Background of Light Weight requirement
Regulation

Environment

CAFE
fuel economy

CO2 and NOX・Aluminum・High strength steel

EU ： Regulation

CO2 emissions-2008：140g/km-2012：130g/km-2020: 95g/km

LightWeight・Safety- IIHS: e.g. Bumper test
- NHTSA: e.g. SINCAP+ Compensation- Euro-NCAP・Comfortable
T. Aiura, Aluminium 2014 Conference, 08 October 2014.

・CFRP
・Magnesium・Stability
・Drivability- Front weight reduction- Lower center of gravity- Electric control system
3

CO2 Emission Control
Fuel Economy

ReduceWeight of Car body
Actual net weighｔ hasincreased due tosafety and comfort
system.

AluminumLight Material

Aluminum wroughtHigh Strength SteelHigh Strength SteelThin gauge
Aluminum casting

2000

2010

2020
PHV, EV

HEV

Diesel CVT Turbo

1990
Steel1980

G.E

Improve
Efficiency of Power Train
4T. Aiura, Aluminium 2014 Conference, 08 October 2014.

Aluminum applications

Suspensions

Doors

PanelsFramesEngine block

120Kg/Car
４５ alloys

Wheel

Re-infores

Structures
HE

Radiaters
Tubes
Braking systems

BMW5： Aluminum Fr structures

CoversMult
Conecters
T. Aiura, Aluminium 2014 Conference, 08 October 2014.

5Aluminum applications for Closure panels

ﾛｰﾄﾞｽﾀｰT. Aiura, Aluminium 2014 Conference, 08 October 2014.

6

■ Comparisons of Steel and Aluminum
60

SteelHigh Strength
Steel (HSS)

Advanced High Strength Steel(AHSS) >780MPa

Elongation (%)

50

MildIF

40

Al-Mg
30

HSLA

Dual Phase

TRIP

20

Al-Mg-SiMS

10

Hot Stamping

Aluminum Al-Zn-Mg
00

200

400

600

800

1000

1200

Ultimate tensile strength (MPa)Aluminum Alloy
Cold Stamping

Roll Forming
Hot Stamping

T. Aiura, Aluminium 2014 Conference, 08 October 2014.

1400

1600

1800

Comparisons of parts cost by materials
HOOD Panels
Cost/hood
コスト（部品）
80000円/個

CFRP
CFRP製フードhood40000
難燃Mg合金製

Magnesium

30000

PA66・PPE製
PPE

20000

10000
２０Kg

オールAL製Aluminum

１５Kg
GA４００製

Steel

10Kg

5Kg

Netweight Kg/hood
部品重量（重軽）8T. Aiura, Aluminium 2014 Conference, 08 October 2014.

Contents
The background on light weighing requirementsof automotive body structures
Light weighting technologies of Closure Panels
by Aluminum Alloy
Advantages of Aluminum on Closure panel applications
Effect of additive on high paint bake response of 6xxx alloy.
Forming & Joining technologies

Aspects on light weighting for Automotive bodyin future
9T. Aiura, Aluminium 2014 Conference, 08 October 2014.

Development of Aluminum Sheetfor Automotive Body PanelHistory of aluminum alloys developed
for automotive body sheets
Past
JPN : 7xxx

Now and Future

5xxx

Development alloy

6xxx alloy (outer/inner panels)
5xxx alloy (inner panels)

Conventional alloy

EU : 2xxx

6xxx

6xxx alloy (outer/inner panels)
5xxx alloy (inner panels)

Conventional alloy

USA : 2xxx

6xxx

106xxx alloy (outer/inner panels)

T. Aiura, Aluminium 2014 Conference, 08 October 2014.

New 6xxx alloy development

Strength (after paint baking)To improve required performance for 6xxx,
Kobe Steel is working continuously with our customers.

7xxx(Al-Mg-Zn)

Application
6xxx(Al-Mg-Si)

5xxx(Al-Mg)

Key words

PanelFormability
Paint bake responseHemming
Natural aging control
Roping free

Structural parts

Strength
Energy absorption

Formability
11T. Aiura, Aluminium 2014 Conference, 08 October 2014.

Motivation of Paint Bake Response improvement
Manufacturing process of parts at car manufacturers
Stamping

Sub
Assembly

Paint-baking

Assemblyat 170oC.

Mechanical properties of Al sheets
Lower strength for better
hemming performance.

Higher Paint Bake Responseeven at low temperature.

Microstructure (Transmission Electron Micrograph)
Before paint bake

After paint bakeStrengthening
precipitates
20nm
12T. Aiura, Aluminium 2014 Conference, 08 October 2014.

Properties of Developed 6xxx alloy
Chemical composition & mechanical properties of test materials (Lab)Tensile property: JIS13A Direction 0°RD

Chemical composition (wt%)

Before paint bakeRP0.2/Rm

A80%

n-value
(5%)

RP0.2
MPa

DBH
(*2-*1)
MPa

*1Rm
MPa

RP0.2
MPa

After Bake
*2SiMgCu

Addi-tive

Conventional

1.00.40.15-2371160.49270.30

215

99

Developed

0.80.4-0.06

186

790.42250.34

199120

Paint bake: 2%st.+185oC,20min

Bending test results (R=0.5, 180 deg.)
0°90°Natural aging for 1 month

Conventional

Visible small cracks

1.0mm
1.0mm

Developed

No cracks
13T. Aiura, Aluminium 2014 Conference, 08 October 2014.

Paint Bake Response at 170oC
Newly developed 6xxx alloy showed;-better hemming performance.
-higher Paint Bake Response even at low temp (170oC).
After natural aging for 1 week120

Vickers hardness （HV)110

Developed

Developed
Conventional

100Higher
BH response

9080

Conventional

7060
50Lower initial hardness
 Better hemming performance

40As SHT
0.1+PA

Just after1natural aging

10100

1000

Aging time at 170℃ (min)10000

Fig. TEM observations for the samples,
aged at 170oC for after 20 min.

14T. Aiura, Aluminium 2014 Conference, 08 October 2014.

Evaluation of atomic cluster distribution
Higher Paint Bake Response

Control ofatomic cluster

Approach・ Alloy designing>Contents of Mg and Si>Mg/Si ratio>Additional Elements (Sn)・ Manufacturing process designing

Evaluation technique
Mg atom
Si atom Atomic-scale characterization(3 Dimensional Atom Probe Tomography)

10nm

3DAP instrument in Kobe.
15T. Aiura, Aluminium 2014 Conference, 08 October 2014.

R&D strategy
Material development

Product design
Crush behavior
Thermal distortion control

Conventional

New concept

HIC=1902

D=60mm

2Acceleration (m/s )

2000
1500

Forming technology

Joining

HIC=1026

Conventional

Beam-typeWave-type00

10203040

5060

New concept

New die design concept for deep drawing

1000500

Wrinkle70

CAE

80Exp.

Displacement,x (mm)Hood inner designfor pedestrianprotection

EA
EAwithwithsidesideimpact;
impact; +16%+16%vs.
vs.conventional
conventionalAl
Aldoordoor
Costreduction
potential;
Cost reduction potential;
Decrease
Decreasenumber
numberofofparts
parts&&joints
jointsWeightreduction;-40%vs.
Weight reduction;-40% vs.SteelSteel

New door concept study
T. Aiura, Aluminium 2014 Conference, 08 October 2014.

@200oC
Warm forming
16

Multi Material Solutions
New Al- FCW (Al/Steel joining)
Optimization of
1. Flux (Type/Quantity)
2. Sheath chemistry
3. Welding parameters

Kobe 6K21

AlGA steel plate
Kobe 6K21

SteelLaser braze weldingAl

New Al-FCW (1.2Ø)FCW(Flux-cored wire)

Conventional brazing Al-FCW

GA steel plate

New Al-FCW

Kobe 6K21

SteelGA steel plate

Conventional brazing Al-FCW

Kobe 6K21

SheathFlux(Improves wettability)

MIG braze welding＊Joint development company（Production / sale)
Nippon Engineering Industry and Service: Neis Co. ltd
 Improved weld bead appearance Enable to use conventional aluminum welding equipment
T. Aiura, Aluminium 2014 Conference, 08 October 2014.

GA steel plate

New Al-FCW

Contents
The background on light weighing requirementsof automotive body structures
Light weighting technologies of Closure Panelsby Aluminum Alloy
Advantages of Aluminum on Closure panel applications
Effect of additive on high paint bake response of 6xxx alloy.
Forming & Joining technologies

Prospects on aluminum alloy applications
for light weight Automotive bodies in the future

18T. Aiura, Aluminium 2014 Conference, 08 October 2014.

Mercedes-Benz New C-ClassL(mm)

W
(mm)

H(mm)

W(kg)

EX

4690 1810 1435 1490

New4595 1770 1445 1500

T. Aiura, Aluminium 2014 Conference, 08 October 2014.

CO2Emission ｇ／km

ToyotaNissanHondaﾞ
FHI
Mazdaﾞ
BENZ
VWBMW
AUDI
Jagur1372kg

Improvement of CO2 Emission JC08MODE (GE LDV)
○GE
△HEV
□PHEV
◇EVRange Loverﾞ

IS250
ｼﾞｬｶﾞｰXJ
A6CMazda
RoadStar

A6HV

Legacyｲﾝﾌﾟﾚｯｻ

UP!

E
New C

ｲﾝﾌﾟﾚｯｻHVCamuri

Fit ﾄ

7-HEV
S

Q35

IS300H

Prius PHVFit HVi8i3

WeightLeaf

kg

T. Aiura, Aluminium 2014 Conference, 08 October 2014.

FCV

Tesla

T. Aiura, Aluminium 2014 Conference, 08 October 2014.

The Target parts of Aluminum alloy
Side panel

T. Aiura, Aluminium 2014 Conference, 08 October 2014.

22

Summary• The light weighting technologies of body structures will be still oneof the most crucial solutions for CO2 emission issue. Aluminum will
be one of the most capable materials. Nonetheless Cost andmaterial performance need to be improved to be applied widely.

• There is a big potentiality to improve the Bake Hardening responseof 6xxx alloys for Automotive parts, introducing additives. The
mechanism has been studied.
• The improvement of press forming performance, strength andcrush behaviors are crucial for further applications of aluminum inorder to be used for deep-drawing parts and structures.

23T. Aiura, Aluminium 2014 Conference, 08 October 2014.

Thank you for your attention.

24T. Aiura, Aluminium 2014 Conference, 08 October 2014.