Researches on Microstructure and Tensile Properties of Laser Repaired β-riched Ti17 Titanium Alloy

In this paper,the wrought TC17 titanium alloys with small defect on the surface had been repaired by laser.The microstructure evolution and the microhardness distribution in the laser deposited zone(LDZ)、heat affected zone(HAZ)and the substrate zone(Substrate)were investigated comparatively.The results show that:the grain boundaries is blurred in the LDZ with the epitaxial growth ofβcolumnar crystal,neighboring gain is difficult to distinguish and the microstructure is small dendrites structure with rapid solidifition without alpha phase precipitation.The wrought substrate is composed of duplex microstructure.The HAZ experience a continuous microstructural transition from the SZ to the LDZ.Microhardness test results show that:the microhardness of LDZ withoutαphase is lowest,that of SZ is highest,and that of HAZ presents middle transition state.Tensile results show that the strength of laser repaired specimen is higher than that of forgings,but the plasticity is lower than the latter.