Effect of Welding Speed on Properties of Laser Welded Joints of Commercially Pure Titanium TA2

Commercially pure titanium TA2 was laser welded at different welding speeds (1.0,1.2,1.6 m·min^-1). The effect of welding speed on microstructure, hole expanding property, stamping performance and tensile properties of joints was studied. The results show that the microstructure of weld center in the joint consisted of coarse α grains and a small amount of acicular α grains when the welding speed was 1.0 m·min^-1 or 1.2 m·min^-1, and consisted of acicular α grains when the welding speed was 1.6 m·min^-1. The microstructure of heat affected zone in the joint was composed of coarse α grains and irregular serrated α grains. The grain size of the joint decreased with the increase of welding speed. The hole expanding rate and cupping value of joints increased with the increase of welding speed. When the welding speed was 1.6 m·min^-1, the joint showed the best hole expanding property, stamping performance and forming performance. The yield strength, tensile strength and elongation of the joint increased first and then decreased with the increase of welding speed. When the welding speed was 1.2 m·min^-1, the joint had the best tensile properties. The fracture modes were all ductile fracture.