1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

300

600

900

1200

1500

1800

0 50 100 150 200

Co

olin

g ra

te /

Ks-

1

Tem

pera

ture

/K

Time /μs

Temperature2

Cooling rate2

0 51 2 3 4

Tokyo Institute of Technology School of Materials and Chemical TechnologyKumai-Muraishi laboratory

・A welding method for metal plates with high speed and incline collision.・A solid-state welding.・A useful method for dissimilar metal welding. ・A characteristic wavy interface and a few intermediate layer are formed.

Explosive welded sample(Al side)

Explosive welded sample(SS400 side)

Flyer plate: Al (A1100)Parent plate: Fe (SS400)Size: 300×300×6mmImpact velocity: 600 m/sImpact angle: 14.6 °Observation: OM, SEMHardness test: Nano indentation

Schematic illustration of Euler/Lagrange coupling model

Impact velocity(V) and impact angle(α) were obtained.

Schematic illustration of Open FOAM

Thermal history and welded interface formation were obtained

Step 1Behavior of the detention

(Euler/Lagrang coupling model) (ANSYS AUTODYN)

Step 2Welded interface formation and

thermal distribution (SPH model) (ANSYS AUTODYN)

Step 3Heat conduction (OpenFOAM)

2000 K

300 K

Explosive welding

Purpose

Schematic illustration of SPH method

Wavy interface and the temperature were obtained.

Al

SS400

Al

SS400Al

SS400Al

SS400

Al

SS400

500 μm

500 μm

500 μm

2000 K

300 K

Welding direction

Introduction

Experimental method

Numerical analysis method

Numerical analysis results

Microstructure and thermal history of explosive welded pure aluminum / SS400 steel joint

ProblemIt is important to examine the thermal history near the welding interface. But thermal history has not been revealed enough.

The purpose of this research is to investigate the thermal history near the welding interface using both experimental and numerical analysis method.

Wavelength: 925 μm, Amplitude: 127 μm

Wavelength: 685 μm, Amplitude: 127 μm

Al

SS400

Wavy interface and thermal distribution can be reproduced by SPH method.

Wavy interface of the specimen

Wavy inter face of the SPH method analysis

Thermal distribution of the wavy interface

Conclusions

Result of the nanoindentation test near the welded interface

Al

SS400 SS400

Al

The region with martenstic structure corresponds to the area of high temperature and high cooling rate according to the numerical analysis.

・Microstructure change and thermal history of the explosive welded pure aluminum and SS400 steel joint were investigated by using both numerical and experimental analysis. ・The numerical analysis revealed that the region with

martensitic structure in SS400 corresponded to the area in which the highest temperature and the highest cooling rate were observed except for the local melting area.

Experimental results

Result of The Open FOAM analysis

Thermal distribution

Hardness of SS400 Matrix

AB

C

D

AB

C

D

CB D

Hardness 7.36 GPa(very high hardness)

FerriteMartensite Hardness 3.29 GPa

(a little high hardness)

2µm 2µm 2µm

A

Near a void

Near a interface

Far from a interface

Welding direction

2.84GPa

cementite＋

Thermal history and cooling rate at various locations2µm

Welded interface formation

0 μs

40 μs

150 μs

0 μs

40 μs

150 μs

Marks of nanoindentation test

Hardness distribution (GPa)

Result of The SPH analysis

100 μm

α-Ferrite (0 - 1183 K)

Austenite etc. (1184 - 1810 K)Al-solid (0 - 933 K)

Intermediate layer Liquid phase

position of the nanoindentation testCorrosion condition: 3%naital 15 s

Observed area

Al

SS400

Explosive

1.E+04

1.E+05

1.E+06

1.E+07

300

600

900

1200

1500

1800

0 50 100 150 200

Co

olin

g ra

te /

Ks-

1

Tem

pera

ture

/K

Time /μs

Temperature3

Cooling rate3

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

300

600

900

1200

1500

1800

0 50 100 150 200

Co

olin

g ra

te /

Ks-

1

Tem

pera

ture

/K

Time /μs

Temperature4

Cooling rate4

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

300

600

900

1200

1500

1800

0 50 100 150 200

Co

olin

g ra

te /

Ks-

1

Tem

pera

ture

/K

Time /μs

Temperature5

Cooling rate5

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

300

600

900

1200

1500

1800

0 50 100 150 200

Co

olin

g ra

te /

Ks-

1

Tem

pera

ture

/K

Time /μs

Temperature6

Cooling rate6

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

300

600

900

1200

1500

1800

0 50 100 150 200

Co

olin

g ra

te /

Ks-

1

Tem

pera

ture

/K

Time /μs

Temperature7

Cooling rate7

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

300

600

900

1200

1500

1800

0 50 100 150 200

Co

olin

g ra

te /

Ks-

1

Tem

pera

ture

/K

Time /μs

Temperature8

Cooling rate8

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

300

600

900

1200

1500

1800

0 50 100 150 200

Co

olin

g ra

te /

Ks-

1

Tem

pera

ture

/K

Time /μs

Temperature9

Cooling rate9① ② ③

④ ⑤

⑥ ⑦ ⑧

・Cooling rate is 104～105 K/s order at many place.・The location ⑤, at the top of wavy interface, exhibited a very high

temperature (1700 K) and a very high cooling.

Temperature riseAl

0 μs

150 μs

Al

SS400

150 μs

SS400

Heat conduction

Material location

Al

SS400

Result of the nanoindentation test at the tip of wavy interface