A new type of solid phase welding, in which torsional force is exerted on the interface together with axial force, has been applied to dissimilar aluminum alloys; one is AA6061 and the other is AA6061 reinforced by SiC particles, the volume fraction of which is in the range from I to 8%. The method is charcterized by lower welding temperature, shorter processing time and hence smaller amount of deformation, in comparison to the previous diffusion bonding. The performance of joints welded at various temperatures (523, 573 and 623K) and pressures (0-90MPa) was evaluated by tensile test, hardness test and microstructure observation. The tensile strength of joint shows linear dependence on the upset pressure, resulting in the magnitude as high as 90% of that for the base metal (AA6061). The joint, however, is much less ductile than any one of the Base metals though the ductility tends to increase with increase in the welding temperature. It is also found that the amount of SiC particles has almost no effect oil the joint efficiency.
