30 mm退火态TC4钛合金EBW接头组织与性能研究

为了提升钛合金的焊接效率和质量，采用电子束焊接方式对30 mm退火态TC4钛合金进行焊接试验，并对焊接接头进行力学性能检测、显微组织分析及残余应力测试，通过扫描电镜对断口形貌进行分析，研究完全退火态TC4钛合金EBW接头组织与性能。结果表明，接头焊缝区由针状马氏体α′相和分布在原始β晶界的α相组成，接头热影响区由初生α相、针状马氏体α′相以及少量β相组成。EBW接头抗拉强度平均值略高于母材，EBW接头第二层焊缝区及热影响区冲击功均低于母材，同时两种接头断口形貌均发现大量韧窝，为韧性断裂。接头最大残余拉应力值约为150 MPa，在平行和垂直焊接方向，残余拉应力最大值均出现在焊缝上表面附近区域，而残余压应力最大值均出现在焊缝下表面附近区域。

Microstructure and Properties of 30 mm Annealed TC4 Titanium Alloy EBW Joints

In order to improve the welding efficiency and quality of titanium alloy, the electron beam welding was used to weld the 30 mm annealed TC4 titanium alloy, and the mechanical properties, microstructure and residual stress of the welded joint were tested. The fracture morphology was analyzed by scanning electron microscope, and the microstructure and properties of the fully annealed TC4 titanium alloy EBW joint were studied. The results show that the joint weld zone is composed of acicular martensite α ’phase and α phase distributed in the original β grain boundary, the joint heat affected zone is composed of α phase, acicular martensite α′ phase and small amount β phase composition. The average tensile strength of EBW joint is slightly higher than that of the base metal. The impact energy of the second layer of weld zone and heat affected zone of EBW joint is lower than that of the base metal. Meanwhile, a large number of dimples are found on the fracture morphology of both joints, which is ductile fracture. The maximum residual tensile stress of the joint is about 150 MPa. In the parallel and vertical welding directions, the maximum residual tensile stress appears near the upper surface of the weld, while the maximum residual compressive stress appears near the lower surface of the weld.