Mechanical properties and microstructure features of linear friction welded TC4 titanium alloy joint

The linear friction welding (LFW) experiment of TC4 titanium alloy was carried out with homemade LFW machine (XMH-160).Joints with 100% joining rate were obtained under the optimum parameters based on the experiments.All the tensile test specimens fractured in the base metal of TC4 at a place far form the weld, which indicated that the mechanical properties of the weld are higher than those of the base metal.The microstructure of the joint was observed, and it showed that the thickness of the weld is about 60 μm at the central zone and around 110 μm at the marginal zone, and the metal streamline are distributed symmetrically on both sides of weld.The weld consists of the superfine α+β strucure, and the zone close to the weld consists of αand β phases deformed in different degree, but they did not grow up obviously.The microhardness of the weld is higher than that of the base metal markedly. It is the microstructure features of the weld that contribute to the higher tensile properties and microhardness than those of the base metal.