1986 年 4 巻 4 号 p. 697-703
A suitable friction welding condition to obtain the joint between pure copper and pure aluminium, which had joint efficiency over 100%, was decided. And the welded joint was pressed in the direction of diameter. Mechanical properties, i.e., tensile strength, bend ductility and hardness, micro-structure and fracture behaviour of the as-welded joint and the pressed joint were investigated.
Reduction R was defined as follows:
where d: diameter of joint before pressworking,
t: thickness of pressed joint.
Main results are summarized as follows.
(1) Tensile strength of the welded joint increases with an incraese of reduction ratio and tensile fracture of the joint, pressed in the reduction ratio of above 20%, always takes place in aluminium base metal.
(2) In the cases of reduction ratios of 40% and 48%, the joints have sufficient ductility so that they are able to be bent up to 90° without cracking in bend test. It seems that improvement of ductility by pressworking is owing to spherical projection of weld interface from copper side to aluminium side.
(3) When the pressed joint is broken in tensile test, fracture takes place in aluminium at the position adjacent to weld interface, that is, it takes place in the alloyed layer and aluminium base metal and at the boundary between alloyed layer and aluminium.