Study On The Microstructure And Property Of TC4 Alloy Joints Welded By The Electron Beam

TC4 alloy is a kind of alpha-beta titanium alloy (α-β) with middle strength developed since the 1950s. It is consisted of 6% alpha element aluminium and 4% beta element virginium. The combined properties of high strength, high specific tenacity and good creep property at high-temperature make this alloy the important structural material for the aerospace industries. TC4 alloy can be welded by many kinds of methods such as TIG, MIG, PAW and electron beam welding (EBW in short). Because of the high activeness of the titanium alloys, the inert gases or vacuum shielding is needed in fusion welding. Vacuum electron beam welding has many advantages of high depth-width ratio of seam, small angular distortion and good metallurgic quality and etc. These advantages of EBW make its use expanding in the welding of titanium and its alloys.The microstructure and properties of TC4 alloy joints welded by the electron beam were investigated in this paper with room-temperature impact test, room-temperature tensile test, room-temperature notch tensile test, high-temperature tensile test, endurant tensile test, microhardness test and metallographic analysis. The results showed that the microstructure of the welded seam was α' phase (acicular martensite) — which was transformed from the primary coarse p phase — and a little of remnant β phase. The welded seam had a structure like basket-weave. The microstructure of the HAZ was the mixture of fine acicular martensite and the primary a phase. The results of the property tests indicated that the joints with good performance at room-temperature and high-temperature of TC4 alloy might be obtained by means of electron beam welding (EBW in short). The welded seam had high impact toughness. The tensile...