POSSIBILITY OF LINEAR WELDING OF THIN METAL PLATE BY

UNDERWATER EXPLOSIVE WELDING

Akihisa Mori*, Kazumasa Shiramoto,Masahiro Fujita

Faculty of Engineering, Sojo University

*E-mail: makihisa@mec.sojo-u.ac.jp

EPNM2012

IntroductionUnderwater explosive welding;　 A welding method using underwater shock wave generated by the detonation of explosive in the water.

（ Advantage ）・ Easy to control the pressurizing

conditions by only changing the distance between the explosive and the flyer plate.

・ A flyer plate is accelerated at a high-velocity immediately with in a small stand-off distance.

Schematic　of　the　underwater　shockwave　welding　method　when　the　high-explosive　is　

used.

Flyer plate

Base plate

Possible to weld a thin plate which is difficult to weld by the conventional explosive welding method.

The method to weld partially be developed to make a large-size sample, when the size of thin plate is limited.

The underwater explosive welding technique is suitable to weld the whole thin plate.

Motivation

Thin plate/foil

(size is limited, brittle materials)

Amorphous film ,etc.

Detonating codeDetonating code

Detonating code (fuse):/ flexible code with an explosive core

/ detonation velocity: 6310m/s

/ diameter: 5.4mm

/ common usage;

ignition of explosive

Core: Pentaerythritol tetranitrate

(PETN)

Covering materials:

Thread, paper, asphalt

(for waterproof)

KAYAKU JAPAN Corp.

Welding of lap jointsWelding of lap joints ((Ref: B. Crossland , Explosive welding of metals and its application)

In the past report, no welding area is generated when the line explosive is set on the flyer plate.

Because the flyer plate is collided to base plate without an angle or with a small angle in this area.

Weldability window proposed by Wittman and DeribasRef. M.A.Meyers, Dynamic Behavior of Materials

Horizontal collision point velocity, Vc

Col

lisi

on a

ngle

,

Velocity of welding, Vc

Dyn

amic

ang

le o

f ob

liqui

ty,

2sin

2

VcVp

Velocity of welding, Vc

Dyn

amic

ang

le o

f ob

liqui

ty,

2sin

2

VcVp

2sin

2

VcVp (1)

(2)(3)

(4)Relation of the collision velocity Vp, the collision angle β and the horizontal collision velosity Vc

2V2V cp

sin

To obtain the good welding in explosive welding, the collision angle β and the horizontal collision velocity Vc, or the collision velocity, Vp are in the area enclosed with four boundary lines shown the upper figure.

Setup of underwater explosive welding Setup of underwater explosive welding technique using detonating codetechnique using detonating code

Base plate

　 Reflector

Anvil

Explosive holder

Flyer plate

Detonating code

Spacer

Front of the underwater shock wave

Distance from the center of detonating code to the sample

Thickness of spacer = Stand off distance

Width of gap

The front of underwater shock waveDetonating direction

（ 6km/s ）

Detonating code(D.C.)

Sample setup

　

l = 0 mm, 9 mm, 14mm

w=5 mm, 10mm

11 mm

Stand-off

x = 0 mmx = 0 mmWelding direction

Flyer: Al (0.3mm) 304ss (0.1mm)

Base: Cu (0.3mm)

hc

hc: distance from the center of explosive to the surface of sample

l : distance from the explosive holder to the edge of gap

Experimental assembly

ReinforcementWater

Bottom plate

Reflector

Guide

　

Bottom plate

Reflector

Anvil

Base plateSpacer

Flyer plate

Detonating code

50 mm

70 mm

Explosive holder

50 mm

Experimental results

Flyer : Al (0.3mm)Base: Cu(0.3mm)

gap gapw =10mm

x10 x5

50 μm 50 μm 50 μm

50 μm 50 μm 50 μm

Spacer(304SS)

Al

Cu

Spacer

Al

Cu

x10 = 0.0 mm x10 = 5.0 mm x10 = 10.0 mm

x5 = 0.0 mm x5 = 2.4 mm x5 = 4.8 mm

Trapped metal jet

w =5mm

l = 9 mmStandoff : 0.1mm(stainless steel)hc = 6.3 mm

Experimental results

x10 x5

50 μm 50 μm 50 μm

50 μm 50 μm 50 μm

SpacerAl

Cu

Spacer

Al

Cu

x10 = 0.0 mm x10 = 2.3 mm x10 = 4.6 mm

x5 = 0.0 mm x5 = 2.7 mm x5 = 4.9 mm

Trapped metal jet

Spacer

l = 9 mm

gap gapw =10mm w =5mm

Flyer : Al (0.3mm)Base: Cu(0.3mm)

Standoff : 0.1mm(stainless steel)hc = 9.3 mm

200μm

Experimental results

l = 9.0 mm, w = 5 mm

200μm200μm200μm

Flyer : Al (0.3mm)Base: Cu(0.3mm)

Standoff : 0.038mm(amorphos film)hc = 6.3 mm

200μm

100μm

Experimental results

l = 9.0 mm, w = 5 mm

Flyer : 304 stainless steel (0.1mm)Spacer : 304 stainless steel (0.1 mm)hc = 6.3 mm

200μm

100μm

Experimental results

l = 9.0 mm, w = 5 mm

Flyer : 304 stainless steel (0.1mm)Spacer : Aluminum foil (0.011 mm)hc = 6.3 mm 50μm

Experimental setup

Base plate

　 Reflector

Anvil

Explosive holder

Cover plate

Detonating code

Spacer

Front of the underwater shock wave

Distance from the center of detonating code to the sample

Thickness of spacer = Stand off distance

Width of gap

Amorphous

Amorphous film/ copper combination

Amorphous (MBF20, 38μm)

Cu(0.3mm)

l = 9.0 mm, w = 5 mm, Cover: Al, standoff: 0.038mm

Cu(0.3mm)

l = 0.0 mm, w = 10 mm, Cover: 304SS (0.1mm), standoff: 0.011mm

Welded length (without cracks ) : about 1.2 mm

Amorphous (MBF20, 38μm)

Numeical modelmaterials solver

(1) Water Euler

(2) Reflector （ 304SS ） Euler

(3) Detonating code Euler

(4) Base plate （ Cu ） Lagrange

(5) Cover plate （ Al ） Lagrange

(6) Spacer （ Al 0.1mm ） Lagrange

(7) Flyer （ Amorphous film ）

Shell

(1) (6)

(5)

(4)

(3)(2)

Starting point of detonation

(7)gapx = 0 mm x = 10 mm

Numerical results

X

Lower limit

*) standoff distance = 0.1mm

Numerical results

*) standoff distance = 0.1mm

Summary

In this study, experimental and numerical results of for the underwater explosive welding method using the detonating code are introduced.

By the observation using the optical microscope, the good welding was achieved in case of a thin aluminum plate and a thin copper plate combination, even if the standoff if the standoff was extremely short.

In the materials combination of amorphous film and a copper plate, the welding was succeeded although cracks were generated.

200μm

20μm

Future plan

Research center for advances in impact Research center for advances in impact engineering, SOJO Universityengineering, SOJO University

TEMTEM

Water tank in explosion roomWater tank in explosion roomExperimental devise to detonate Experimental devise to detonate

explosives in vacuumexplosives in vacuum

Thank you for your attentionThank you for your attention

Setup of underwater explosive welding technique Setup of underwater explosive welding technique using detonating codeusing detonating code

Plan view

The front of underwater shock wave

Top view

Propagating direction of underwater shock wave (welding direction)

Reflector

Explosive holder Flyer plate

Base plate

Spacer

Anvil

Detonating direction

（ 6km/s ）

gap

In this setup, an underwater shock wave acts for the flyer plate diagonally. Then, the welding is achieved in the limited area because the flyer plate is collided with a certain angle

D.C.

Detonating code(D.C.)

Simulation model

60mm

35mm

11mm

10mm 15mm

15m

m

9mm

Φ5.5mm

ゲージ設定

Simulation model(Gauge)

x =0mm0.5mm

ゲージ間隔 :0.5mm

Experimental results

x10 x5

50 μm 50 μm 50 μm

50 μm50 μm 50 μm

Al

Cu

Al

Cu

x10 = 0.6 mm x10 = 4.1 mm x10 = 7.7 mm

x5 = 0.5 mm x5 = 2.1 mm x5 = 4.7 mm

Flyer : Al (0.3mm)Standoff : 0.3mmhc = 9.3 mm

l = 9 mm

gapw =10mm w =5mm

Cu(0.3mm)

Amorphous film/ copper combination

l = 0.0 mm, w = 10 mm, Cover: 304SS (0.1mm), standoff: 0.011mm

Welded length (without cracks ) : about 1.2 mm

Amorphous (MBF20, 38μm)

200μm

20μm

Numerical analysis(AUTODYN-2D)

Al 1100-H12

PVC

DF

Water

S.S. 304

Explosive holder

VoidSpacer (PVC or S.S. 304)

Flyer (Al1100-H12)

Starting area of detonation

*) Excluding the base plate

Measuring point (0.5mm-interval)

Numerical analysis(AUTODYN-2D)

Parameters with horizontal position (A2, A4)

2

4

6

8

10

12

14

16

0

500

1000

1500

2000

2500

3000

3500

0 5 10 15 20 25 30 35

Col

lisi

on a

ngle

,

/ deg

rees

Hor

izon

tal c

olli

sion

poi

nt v

eloc

ity,

Vc

/ ms-1

Horizontal potion, x / mm

Vc [#A4]Vc [#A2]Beta [#A4]Beta [#A2]

stable areaarea closed

to the spacer area closed to the spacer

unstable area

unstable area

Welding direction

Parameters, such as the horizontal collision point velocity, collsion angle, with horizontal position are shown in the upper figure.

As shown in this figure, parameters are changing linearly with the horizontal position, excluding the position slightly far from the spacer and around the end side.

Weldablity window obtained by numerical results

2

4

6

8

10

12

14

16

18

0 500 1000 1500 2000 2500 3000 3500 4000

Col

lsio

n an

gle,

β/

deg

rees

Horizontal collision point velocity, VC / ms-1

#A4: SOD 0.3mm #A2: SOD 0.1mm

1020

406080100120140160180200 kJ/m2DKE=

Lower limit

Numerical results agree well with the experimental results ( A2: welded length = 5.7mm, welding conditions become same values, compared with the 0.3mm-standoff case.