The Influence Of Parameters To The Welding Joint In TC4 Titanium Alloy Micro-plasma Arc Surfacing Process

This paper analyzes the effects of parameters in a TC4 titanium alloy sheet micro-plasma arc surfacing process on the joint forming. Results of experiments applied show that the wire feeding speed and welding current have larger influence on joint forming, there is no difference on the effect of different thickness of sheet.Distance from the welding gun to the piece has smaller influence on joint forming,while different thickness of sheet will bring a large difference on joint forming.Experimental results show that TC4 titanium micro-plasma arc welding seam is mainly composed of baskets organization consisting of ?' martensite phase and a few? phase; Heat affected zone is mainly composed of ? 'phase, the primary ? phase and? phase, and the organization distribute unevenly. The number of organizations is larger near the fusion line in heat affected zone; Different welding parameters change the microstructure of weld seam. Welding parameters have little effect on phase; The hardness of welding joint decrease gradually from weld seam- heat affected zone-basic metal. Welding parameters have smaller influence on the hardness of welding joint. The tensile strength of the welded joints is slightly higher than the tensile strength of the base metal. The weld seam performs the brittle rupture characteristic. The fracture toughness of the weld zone is poor compared to the parent material.Stress relief heat treatment process has less effect on joint microstructure and phase composition, also has a certain improving effect on hardness. Fracture locations of heat treatment tensile specimens have a difference with the non heat treatment tensile specimens. The influence of heat treatment on specimen's fracture toughness is not obvious.