增材制造TC4合金的电子束焊接头组织和性能研究

Microstructure and Mechanical Properties of Electron Beam Welding Joints of Additive Manufactured TC4 Alloy

对电子束熔丝增材制造TC4钛合金进行了电子束焊接,分析了接头的组织特征和力学性能。结果表明,母材区的显微组织由网篮状α+β相组成,热影响区由β转变组织和马氏体α′组成,且距焊缝越近马氏体含量越高。焊缝区由大量细长的马氏体组成,且由焊缝顶部至底部马氏体越来越细小。母材区硬度最低,热影响区的硬度随距焊缝中心线距离的减小明显增大,焊缝区显微硬度最高。焊后接头断裂在母材一侧,接头抗拉强度为875 MPa,伸长率为7%,接头断裂形式为韧性断裂。

TC4 titanium alloy fabricated by the electron beam additive manufacturing were welded by electron beam welding, and the microstructure and mechanical properties of the joints were analyzed. The results reveal that the microstructure of the base metal zone is composed of basket-wave shaped α+β phase, and the heat affected zone is composed of β-transformed structure and α′martensite. With closer to the weld joint, the martensite content is increased. A large number of elongated α′martensite exists in the weld zone, and the martensite is finer from the top to the bottom of the weld. The hardness of the base metal zone is the lowest, while the weld zone is the highest, and that of the heat-affected zone is increased significantly with the decrease of the distance from the center line of the weld. Joints are broken on the side of the base material, where the ultimate tensile strength and the elongation of the joint is 875 MPa and 7%, respectively, and the fracture type is characterized by ductile fracture.