大厚度TA17钛合金磁控窄间隙TIG焊接头组织和力学性能

Microstructure and Mechanical Properties of Welded Joints of TA17 Ti Alloy by Magnetically Controlled Narrow-Gap TIG Welding

对120 mm厚的TA17钛合金板进行了磁控窄间隙TIG焊接试验,系统表征了该焊接接头不同区域的显微组织和力学性能,并阐明接头显微组织演变过程及其对力学性能的影响。结果表明沿接头横向存在显著的组织不均匀性:靠近焊缝的母材区主要由拉长的α晶粒和沿晶界分布的β相构成,接头热影响区组织为粗大α集束构成的魏氏组织,熔合区为细小α片层交错组成的网篮组织。沿接头厚度方向,显微组织差异较小,接头上层熔合区观察到少量马氏体片层组织。接头熔合区硬度显著低于母材区的,拉伸过程中熔合区优先发生屈服,随后成为塑性变形集中区域,导致接头强度和塑性较母材降低。

The magnetically controlled narrow-gap TIG welding experiment was conducted for the 120 mm thick TA17 titanium alloy plate.The microstructure and mechanical properties of different regions of the welded joint were characterized systematically,and the evolution process of the microstructure and its influence on the mechanical properties were clarified.The results show that the microstructures of the joint in the transverse direction have significant difference.The base metal area near the weld zone is mainly composed of elongatedαgrain andβphase which is distributed along grain boundary.The heat affected zone is the Widmannian structure composed of largeαcluster,and the fusion zone is a net basket structure composed of interlacedαlamellar.In the thickness direction of the joint,there is almost no difference in the microstructure,and a small amount of martensite lamellar microstructure is observed in the upper fusion zone of the joint.The hardness of the fusion zone is significantly lower than that of the base metal zone.During tensile process,the fusion zone yields first,and then becomes the area where the plastic deformation concentrates,resulting in the decrease of the joint strength and plasticity.