采用光学显微镜和场发射扫描电镜观察了TC4钛合金激光焊接接头的显微组织,测量了接头焊缝中心到母材的显微硬度。结果表明,母材由α相和其相界上断续分布的粒状β相组成。焊接接头组织由粗大等轴晶区、柱状晶区、细等轴晶区和热影响区过热组织组成。粗大等轴晶区组织形态有层片状α+β、魏氏体α和网篮状α+β3种,其显微硬度略低于柱状晶区和细等轴晶区,但比母材高;柱状晶区和细等轴晶区组织为针状马氏体,柱状晶区显微硬度相对较高。热影响区显微硬度与母材相差不大。 The microstructure of TC4 titanium alloy laser welded joint was observed by optical microscope and field emission scanning electron microscope, and the microhardness of the joint weld center to the base metal was measured. The results show that the base metal is composed of α phase and granular β phase which is discontinuously distributed on its phase boundary. Welding joint organization by the coarse equiaxed zone, columnar zone, fine equiaxed zone and heat affected zone overheating organization. The morphology of the coarse equiaxed zone is lamellar α + β, westenite α and basket α + β. The microhardness is slightly lower than that of the columnar zone and fine equiaxed zone, but higher than the base metal ; Columnar zone and fine equiaxed zone were acicular martensite, while columnar zone had relatively higher microhardness. HAZ microhardness and base metal or less.