TC4钛合金窄间隙激光填绞股焊丝焊接接头组织及性能

Microstructure and mechanical properties of TC4 titanium alloy welded joint by narrow gap laser welding with filler stranded wire

采用实心绞股焊丝,通过窄间隙激光填丝焊对TC4钛合金进行焊接,分析了激光填丝焊接头各区域的微观组织及形貌,并测试了焊接接头的显微硬度、室温拉伸性能及冲击性能等力学性能。结果表明,焊缝截面整体成形良好,无明显未熔合和气孔等缺陷,母材由等轴α+β相组成,热影响区晶粒比母材稍大,热影响区由针状α′马氏体+初生α相组成,焊缝由粗大的原始β柱状晶和内部网篮状α′马氏体组成,焊接接头的抗拉强度平均值达940 MPa,拉伸断裂在母材,断口韧窝较浅,主要表现为韧性断裂特征,焊缝的显微硬度平均值为375 HV,高于母材及热影响区。

Narrow gap laser welding of TC4 titanium alloy was carried out with stranded solid wire,microstructure and morphologies of welded joints were analyzed,and mechanical properties of welded joints,such as microhardness,tensile properties at room temperature and impact strength,were tested.The results showed that weld cross section was well formed without obvious defects such as incomplete fusion and porosity.Base metal was composed of equiaxedα+βphases.Grains of heat-affected zone were larger than those of base metal,heat-affected zone consisted of acicularα′martensite+primaryαphase,and weld was composed of coarse primitiveβcolumnar grains and inner basketα′martensite.Average tensile strength of welded joints was 940 MPa.Tensile fracture located in base metal,and dimple of fracture was shallow,whose main characteristic was ductile fracture.Average microhardness of weld was 375 HV,which was higher than that of BM and HAZ.