This paper describes a butt-welding of AZ31B magnesium alloy plate to commercially pure titanium (CPTi) plate by the solid state welding using a rotating probe with a thread. The effect of the right-hand and left-hand thread on the tensile strength and microstructure was investigated. The following results were obtained in this study.
The probe with a thread increased the tensile strength of a joint by about 79% or less compared with without a thread. There were little differences in the maximum tensile strength of the joints made by the right-hand thread and the left-hand thread. Using the probe without a thread, the fragments of CPTi were produced in a continuous form, but using the probe with a thread, the fine fragments of CPTi tended to scatter in Mg alloy matrix. The increase in the tensile strength of the joints using the probe with a thread was considered to be due to the sufficient plastic flow of Mg alloy caused by the fine fragments of CPTi scattered in Mg alloy matrix. However, the tensile strength of the joint was lower than that of the parent material and the fracture path occurred around the interface. X-ray diffraction analysis revealed a deformation texture with the (002) basal plane near the interface of the magnesium side. It seems that both of the decrease in Al concentration in the Mg alloy and the formation of the deformation texture with the (002) basal plane caused the tensile strength lower, compared with parent material.