TC4钛合金激光锁面对接焊的微观组织及力学性能研究

Study on Microstructure and Mechanical Properties of Laser Locking Surface Butt Welding of TC4 Titanium Alloy

采用激光焊接技术对TC4钛合金工字型法兰底板与蒙皮进行了锁面对接焊,研究了焊接接头的宏观成形、微观组织和力学性能。结果表明,采用激光锁面对接焊工艺的接头成形良好,没有咬边、裂纹和气孔等缺陷。焊缝组织为针状马氏体α′相和分布在原始β晶界的α相,热影响区由初生α相、针状马氏体α′相以及少量β相组成。焊缝和热影响区的硬度高于母材,最大硬度出现在热影响区靠近焊缝处。锁面对接接头拉伸性能良好,试样断于母材处,采用激光锁面对接焊工艺可以对工字型法兰底板与蒙皮进行高性能连接。

The I-shaped flange floor and skin of TC4 titanium alloy were joined by lock surface butt welding using laser welding technology. The macroforming, microstructure and mechanical properties of welded joints were investigated. The results indicate that the forming of welded joint is good without defects such as undercut, visible cracks or porosity. The microstructure of weld zone is mainly comprised of acicular martensitic α′ phases and α phases distributing at prior β grain boundaries and the HAZ is composed of primary α and acicular martensite α′ phases and a small amount of β phases. The microhardness of the HAZ and weld zone is higher than that of the TC4 base metal and the maximum hardness is located in the heat affected zone near the weld. The tensile properties of the locking surface butt joints are good, and the sample fractures at the base metal. Laser locking surface butt welding technology can join bottom plate of flange and skin with high performance.