IMPACT WELDING OF ALUMINUM TUBE TO A STAINLESS STEEL TARGET – EFFECT OF DEFORMATION OF TUBE ON BONDING CONDITION - H. DATE Department of Mechanical Engineering Tohoku Gakuin University 1-13-1 Chuo, Tagajo 985-8537, Japan ABSTRACT A tubular aluminum projectile, subjected to a longitudinal impact, was impact-welded onto a stainless steel target using a gas gun at impact velocities of 200 m/s or more. The bonded area was estimated using acoustic tomography. The microstructures and element distribution in the joint were analyzed by means of SEM and Energy dispersive X-ray spectroscopy. It appeared that the aluminum projectile was bonded to stainless steel target at an impact velocity from 200 to 300 m/s. The compound layer was observed at the joining interface of aluminum/stainless steel by SEM. The bonding strength of aluminum/stainless steel joint showed a maximum of 190 MPa at 230 m/s and decreased with lower impact velocity. The bonding strength at impact velocities of 220~ 240 m/s was stronger than fracture strength of the aluminum projectile. KEYWORDS tube impact-welding, aluminum/stainless steel joint, compound layer, bonding strength INTRODUCTION The bonding technique of a tube to a tube or a plate is one of important techniques in mechanical engineering. It has been reported previously by Date and others that a cylindrical projectile with a flat end subjected to a longitudinal impact was bonded to a target plate at impact velocities of 200 m/s or more using a gas gun [1]. A tube was also impact-welded on a flat target using the same gas gun [2]. However the bonding mechanism of the tube could not be deduced by the results of the bar, since the two deformation processes during impact were different. Here, the impact welding of an aluminum tube to a stainless steel target was carried out and the bonding mechanism was examined by the bonding area, deformation process, bonding strength and the compound layer at the joining interface. The differences of the bonding mechanisms of the bar and the tube were clarified with some of the points described above and the proper phenomena about the tube were found out in the experiment.
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