Abstract
Pure titanium and AZ31B magnesium alloy sheets were butt joined by friction stir welding method (FSW) with different joining parameters by tool rotating speed and changing probe position from the joint interface. Al-rich titanium layer with under 2 μm in thickness was formed at a joint interface in pure titanium side in the following FSW conditions (travel speed: 300 mm/min, tool rotating speed: 1500 rpm , probe position: 1.2 mm into titanium). Near the joint interface, the grain of titanium was deformed by both heat effect and stirring force , and vickers hardness of titanium increased to 200 HV 0.05 in comparison with base metal hardness 150 HV 0.05 because of work hardening. However AZ31B showed no obvious hardness change. Tensile strength of the joint increased with changing the prove position into the titanium side and the maximum strength 156 MPa was obtained at probe position of 1.2 mm into titanium side. Fracture occurred in the stir zone of AZ31B.
