IWJC-Korea 2017
April 12th , 2017, Gyeongju

Laser Roll Welding of Dissimilar
Metal Joints
Muneharu KUTSUNA(Advanced Laser Tehnology Research Center)
Hitoshi OZAKI( Mie University)

1． Introduction
Needs for multi material structures

Fe - Al equilibrium phase diagram

BrittleIMCDuctile IMC

Mechanical Properties of Intermetalic
Compounds in Fe-Al series
Hardness and fracture toughness ** M.Yasuyama and K.Ogawa, JJWS,1996

Flow curves under compressive loading *（Yasuyama et al Fe-rich IMC are ductile Al-rich IMC are brittle
 Therefore, if amount of Fe-rich ductile IMC in interface
layer is increased at the expense of Al-rich brittle IMC, thejoint strength may improve.

Mutual Diffusion Coefficient
DFe in Al = 1.2 10-5 m2/s

DAl in Fe = 5.2 10-4 m2/s

EFe in Al = 135,000 J/mol

EAl in Fe = 246,000 J/mol
for 900oC-1100oC

for 20oC-642oC
3.0Diffusion Coefficient, 10-9 cm2/s

DFe in Al
DAl in Fe

2.0

1.00.0-1.00200

400

600

Temperature, oC

8001000

Growth of Intermetallic Compound

Time-Temperature-Phase (TTP) Diagram

Pressure: 31.5 MPa

２．Laser Roll Welding for Fe-Al joint
2.4kW CO2 laser with TEM 01* mode

Reflecting Mirror Angle : 57.5oDistance between Beam
Spot center and Roller : 17 mm
Beam Diameter: 2.5 mm minor
3.5 mm major
Shielding Method: Argon Gas shield
Insert material used
: Aluminium brazing flux,
K AlF4:K2AlF6.H2O

Direction of table travel

Details of Sheet Clamping

Classification of Welding Processes
Self-melting Zone

Fusion Zone

AAPressureAA
1．Fusion welding 融接A Pressure
AorB

2．Solid-state welding 固相接合
Brazing / Soldering materials

AAor

B
3．Brazing ろう付

orB

4． One side Melting Fusion Welding=Laser roll weldingProcess Features of LRW
1) formations of ductile intermetallic compounds such as FeAl and Fe3Al or
eutectic phase after self-melting in the interface layer;2) keeping the intermetallic compound layer thickness less than 10 µm;
3) the idea of using a sharp intensified fast moving heat source to just cause
wetting and diffusion for a very short period to form a metallic bond.
4) Heating is only one metal sheet by laser

３．Laser Roll Welding of SPCC steeland Aluminum Alloys

Research Background
Automobile industry aims at• Improving fuel efficiency of vehicle• Minimizing environmental pollution (CO2Gas)
One of the ways isto reduce vehicle weight by
Use of high strength steels• Amount of steel in the vehicle should be reduced
by using aluminum alloys which have highstrength-to-weight ratio•

For example, use of steel-aluminum hybrid structures.

Set up of SPCC steel and A5052 AlloyTensile test specimen

SPCC base metal was brokenErichsen Test Specimen
SPCC SteelAluminumWelding Condition of LRW
Laser Power
1.0 kW 〜 2.0kW
Travel Speed
1.0〜 3.2 m/min
Beam spot dia.
3mm 〜 5mm
Roll Pressure
100 〜 202 MPa
Shielding Method Argon Gas shielding
Insert Material used Aluminium brazing
flux,
KAlF4:K2AlF6.H2O

3.1 Experiment
1) Materials used
SPCC steel for car body ; Thickness 0.7 and 1.0 mm
Size : 23mm x 200mm and 40mm x 200mm
Preparation: Polishing with Emery paper #120
Coating: Graphite coating
A6022 and A6K21 : Thickness 1.2 mm
Size : 23mm x 200mm and 40mm x 200mm
Preparation: Polishing with Emery paper #400
Coating: FL-7 flux for Al brazing

2) Laser Facility used
3kW Single mode Fiber laser (IPG)Laser Roll Welding Machine3) Welding condition
Specimen

Laser

Defocusing Travel

No.

PowerDistance（ W）

Ｄｆ（mm） ｍｍ/sec

ＡＴ－１

２２００

１６５

１５１００

Ａｒ１５＋１５ No Flux, Copper Backing

ＡＴ－２

２２００

１６５２０１００

Ａｒ１５＋１５ No Flux, Copper Backing

Ａｔ－８

２１００

１６５

１３８００

Ａｒ１５＋１５ With Flux, Copper Backing

ＡＴ－９２１００１６５１４８００

Ａｒ１５＋１５ With Flux, Copper Backing

ＡＴ－１０

２１００１６５１５８００

Ａｒ１５＋１５ With Flux, Copper Backing

ＡＴ－１１２１００

１６５

１６８００

Ａｒ１５＋１５ With Flux, Copper Backing

ＡＴ－１２２１００１６５１７８００

Ａｒ１５＋１５ With Flux, Copper Backing

ＡＴ－２５２２００

１６７

８１００

Ａｒ１５＋１５ With Flux, Copper Backing

ＡＴ－２６２２００

１６７

１０１００

Ａｒ１５＋１５ With Flux, Copper Backing

ＡＴ－２７

２２００

１６７

１２１００

Ａｒ１５＋１５ With Flux, Copper Backing

ＡＴ－２８２２００

１６７

１４１００

Ａｒ１５＋１５ With Flux, Copper Backing

ＦＡ－２２２００

１６７

１５１００

Ａｒ１５＋１５ With Flux, Copper Backing

ＦＡ－４

２２００１６７

１２１００

Ａｒ１５＋１５ With Flux, Steel Backing

ＦＡ－５

２２００１６７

１２１００

Ａｒ１５＋１５ With Flux, SUS Backing

ＦＡ－６

２２００１６７

１２１００

Ａｒ１５＋１５ With Flux, Alumi. Backing

ＡＫ－２５２２００１６７

８１００

Ａｒ１５＋１５ With Flux, Alumi. Backing

ＡＫ－２６２２００

１６７

１０１００

Ａｒ１５＋１５ With Flux, Alumi. Backing

ＡＫ－２７２２００

１６７

１２１００

Ａｒ１５＋１５ With Flux, Alumi. Backing

speedLoading Shielding

Remarks（Ｎ） Gas and flowrateCross section of Fe-Al jointＦＡ－６ ： Ａｌｕｍｉｎｉｕｍ Ｂａｃｋｉｎｇ

ＦＡ－２： Ｃｏｐｐｅｒ Ｂａｃｋｉｎｇ

Ｃｒｏｓｓ ｓｅｃｔｉｏｎ ｏｆ Ｆｅ－Ａｌ Ｊｏｉｎｔ

ＦＡ－５： Ｓｔａｉｎｌｅｓｓ Ｓｔｅｅｌ Ｂａｃｋｉｎｇ

Interface of joinｔ ＦＡ－６
SPCC steel

A6022 Alloy

Result of EPMAＦｅＡｌ

Re-zaSpecimenNo.

Laser Power（ W）

Defocusing
Distance
Ｄｆ（mm）

ＡＴ－２５

２２００

ＡＴ－２６

RemarkTravelspeedｍｍ/sec

Loading（Ｎ）

Tensilestrength（ＭＰa）

１６７

８

１００

１６９

With Flux, Copper Backing

２２００

１６７

１０

１００１５３

With Flux, Copper Backing

ＡＴ－２７２２００１６７

１２１００１１９With Flux, Copper Backing

ＡＴ－２８

２２００

１６７

１４１００１７９

With Flux, Copper Backing

ＡＫ－２５

２２００１６７

８１００１０２

With Flux, Al Backing

ＡＫ－２６２２００１６７

１０１００１６８

With Flux, Al Backing

ＡＫ－２７

２２００１６７

１２１００２１５With Flux, Al Backing

ＦＡ－２

２２００１６７

１５１００

３３０

With Flux, Copper Backing

ＦＡ－４

２２００１６７

１２１００１２６

With Flux, steel Backing

ＦＡ－５

２２００１６７

１２１００

１５３

With Flux, SUS Backing

ＦＡ－６

２２００１６７

１２１００２９４

With Flux, Al Backing

Tensile test specimen

Copper Backing

Stainless Steel BackingAluminium Backing

Conclusion
1) It is suggested that intermetallic compoundlayer that is formed mainly is ductile
FeAl . As the Backing material are Copper
plate or Aluminum alloy.
2) The tensile strength of laser roll welded
joint using copper backing is 330 Mpa.
It was broken at Base metal of SPCC steel