Microstructure and Mechanical Properties of TC17 Titanium Alloy Laser Welded Joint
In this paper,the laser welding of TC17 titanium alloy was carried out,and the macroscopic mor-phology,microstructure,microhardness and tensile properties of the joint were studied.The results show that TC17 titanium alloy base material is composed of β phase and equiaxed αp phase,and there is a lot of acicular secondary αs phase in β phase.The microstructure of heat-affected zone is complicated.With the decrease of distance from the weld zone,αp gradually decreases,β gradually increases,αs first disappears,then occurs,and finally disappears again.The microstructure of weld zone is mainly composed of columnar dendrites,and the porosity defects were mainly concentrated in the middle and lower part of the weld zone.From the base metal to the weld zone,hardness generally decreased.Affected by the αs phase,the microhardness of the heat-affected zone decreases first,then increases and then decreases.Due to the lowest hardness and porosity defects of weld zone,the tensile fracture of TC17 titanium alloy laser welded joint was in the weld zone.
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