EPNM 2012 POSSIBILITY OF LINEAR WELDING OF THIN

EPNM 2012 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

Introduction Underwater explosive welding; 　A welding method using underwater shock wave generated by the detonation of explosive in the water. （Advantage） Flyer plate ・ 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. Base plate Schematic of the underwater shockwave welding method when the high-explosive is used. Possible to weld a thin plate which is difficult to weld by the conventional explosive welding method.

Motivation The underwater explosive welding technique is suitable to weld the whole thin plate. The method to weld partially be developed to make a large-size sample, when the size of thin plate is limited. Amorphous film , etc. Thin plate/foil (size is limited, brittle materials)

Detonating code (fuse): / flexible code with an explosive core / detonation velocity: 6310 m/s / diameter: 5. 4 mm / common usage; ignition of explosive KAYAKU JAPAN Corp. Core: Pentaerythritol tetranitrate (PETN) Covering materials: Thread, paper, asphalt (for waterproof)

Welding 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 Deribas Ref. M. A. Meyers, Dynamic Behavior of Materials Relation of the collision velocity Vp, the collision angle β and the horizontal collision velosity Vc Collision angle, b (4) (1) æbö V p = 2 Vc sin ç ç è 2ø (3) (2) Horizontal collision point velocity, Vc 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 technique using detonating code The front of underwater shock wave Detonating direction （6 km/s） Detonating code(D. C. ) Front of the underwater shock wave Explosive holder Detonating code Distance from the center of detonating code to the sample Thickness of spacer = Stand off distance 　Reflector Flyer plate Anvil Width of gap Spacer Base plate

Sample setup Welding direction 11 mm x = 0 mm Flyer: Al (0. 3 mm) 304 ss (0. 1 mm) Base: Cu (0. 3 mm) hc Stand-off 　 w=5 mm, 10 mm l = 0 mm, 9 mm, 14 mm 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 Water Reinforcement Guide Reflector Bottom plate Explosive holder Flyer plate Spacer Base plate Bottom plate Reflector Detonating code 70 mm 50 mm Anvil

Experimental results w =10 mm gap Flyer : Al (0. 3 mm) Base: Cu(0. 3 mm) w =5 mm l = 9 mm x 10 Spacer (304 SS) gap Standoff : 　0. 1 mm (stainless steel) hc = 6. 3 mm x 5 Al Cu 50 μm x 10 = 0. 0 mm x 10 = 5. 0 mm 50 μm x 10 = 10. 0 mm Al Trapped metal jet Spacer Cu 50 μm x 5 = 0. 0 mm 50 μm x 5 = 2. 4 mm 50 μm x 5 = 4. 8 mm

Experimental results w =10 mm gap Flyer : Al (0. 3 mm) Base: Cu(0. 3 mm) w =5 mm l = 9 mm x 10 gap Standoff : 0. 1 mm (stainless steel) hc = 9. 3 mm x 5 Al Spacer Cu 50 μm x 10 = 0. 0 mm x 10 = 2. 3 mm 50 μm x 10 = 4. 6 mm Al Spacer Cu 50 μm x 5 = 0. 0 mm 50 μm x 5 = 2. 7 mm Trapped metal jet 50 μm x 5 = 4. 9 mm

Experimental results l = 9. 0 mm, w = 5 mm Standoff : 　 0. 038 mm (amorphos film) hc = 6. 3 mm Flyer : Al (0. 3 mm) Base: Cu(0. 3 mm) 200μm

Experimental results l = 9. 0 mm, w = 5 mm 200μm 100μm Flyer : 304 stainless steel (0. 1 mm) Spacer : 　304 stainless steel (0. 1 mm) hc = 6. 3 mm

Experimental results l = 9. 0 mm, w = 5 mm 200μm 100μm Flyer : 304 stainless steel (0. 1 mm) Spacer : 　Aluminum foil (0. 011 mm) hc = 6. 3 mm 50μm

Experimental setup Front of the underwater shock wave Explosive holder Detonating code Distance from the center of detonating code to the sample Thickness of spacer = Stand off distance 　Reflector Anvil Width of gap Cover plate Amorphous Spacer Base plate

Amorphous film/ copper combination l = 9. 0 mm, w = 5 mm, Cover: Al, standoff: 0. 038 mm Amorphous (MBF 20, 38μm) Cu(0. 3 mm) l = 0. 0 mm, w = 10 mm, Cover: 304 SS (0. 1 mm), standoff: 0. 011 mm Amorphous (MBF 20, 38μm) Cu(0. 3 mm) Welded length (without cracks ) : about 1. 2 mm

Numeical model materials Starting point of detonation (2) solver (1) Water Euler (2) Reflector （304 SS） Euler (3) Detonating code Euler (4) Base plate （Cu） Lagrange (5) Cover plate （Al） Lagrange (6) Spacer （Al 0. 1 mm） Lagrange (7) Flyer （Amorphous film） Shell (5) (3) (1) (6) (4) x = 0 mm x = 10 mm gap (7)

Numerical results Lower limit X *) standoff distance = 0. 1 mm

Numerical results *) standoff distance = 0. 1 mm

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

Future plan 200μm 20μm

Thank you for your attention Research center for advances in impact engineering, SOJO University Water tank in explosion room TEM Experimental devise to detonate explosives in vacuum

Setup of underwater explosive welding technique using detonating code Propagating direction of underwater shock wave (welding direction) Detonating direction （6 km/s） The front of underwater shock wave Reflector Explosive holder D. C. Anvil Plan view gap Flyer plate Spacer Base plate Top view Detonating code(D. C. ) 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

Simulation model Φ 5. 5 mm 60 mm 9 mm 15 mm 11 mm 10 mm 35 mm 15 mm

ゲージ設定 ゲージ間隔: 0. 5 mm x =0 mm 0. 5 mm Simulation model(Gauge)

Experimental results w =10 mm Flyer : Al (0. 3 mm) Standoff : 　0. 3 mm hc = 9. 3 mm w =5 mm gap l = 9 mm x 10 x 5 Al Cu 50 μm x 10 = 0. 6 mm 50 μm x 10 = 4. 1 mm x 10 = 7. 7 mm Al Cu 50 μm x 5 = 0. 5 mm 50 μm x 5 = 2. 1 mm 50 μm x 5 = 4. 7 mm

Amorphous film/ copper combination l = 0. 0 mm, w = 10 mm, Cover: 304 SS (0. 1 mm), standoff: 0. 011 mm Amorphous (MBF 20, 38μm) Cu(0. 3 mm) Welded length (without cracks ) : about 1. 2 mm

200μm 20μm

Numerical analysis(AUTODYN-2 D) Starting area of detonation Flyer (Al 1100 -H 12) Spacer (PVC or S. S. 304) Void Water Explosive holder DF S. S. 304 Al 1100 -H 12 Measuring point (0. 5 mm-interval) PVC *) Excluding the base plate

Numerical analysis(AUTODYN-2 D)

Parameters with horizontal position (A 2, A 4) 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. Parameters, such as the horizontal collision point velocity, collsion angle, with horizontal position are shown in the upper figure.

Weldablity window obtained by numerical results Numerical results agree well with the experimental results ( A 2: welded length = 5. 7 mm, welding conditions become same values, compared with the 0. 3 mmstandoff case.