Weld appearance, microstructure evolution and microhardness of welded joint in the TC4 additive manufactured component TIG welding

Abstract

In this work, TC4 titanium alloy CMT additive thin-walled components is selected as base metal to study the weld formation, microstructure evolution, and microhardness of TIG welded joint. The results showed that the thin-walled components could obtain a good formation after TIG welding. The weld seam was mainly consisted of equiaxed and columnar of β grain. The maximum texture intensity of β phase in the weld surface was only 10.746. Therefore, there was no obvious preferred growth direction in the weld seam. The heat affected bands (HAB) in the zone of weld seam was disappeared due to the base metal no undergone multiple heating cycles after melting. In the weld cross-section and weld surface, the average hardness of base metal is about 334.5 HV and 358.8 HV, respectively. The hardness of weld seam was greater than that of the base metal. The hardness of weld surface was greater than that of weld cross-section. The change of hardness of welded joint was mainly caused by β grain size and α phase.