Li Junzhao, Yu Hang, Yin Xin, Kong Bin, Wen Kai, Sun Qingjie, Wang Bingfeng, Zeng Xianshan
School of Materials Science and Engineering, Central South University, Changsha 410083, China.
Hunan Xiangtou Goldsky Titanium Metal Co., Ltd., Changsha 410083, China.
Materials (Basel). 2024 Sep 26;17(19):4722. doi: 10.3390/ma17194722.
Titanium and titanium alloys with a medium thickness of 5 to 12 mm are widely used for ocean platforms, military equipment and in other fields because of their light weight, appropriate strength and corrosion resistance. In this study, autogenous laser welding and narrow-gap laser welding processes were researched and compared, and the welding characteristics, weld microstructure and joint strength were analyzed. The results showed that autogenous laser welding had higher efficiency, narrower weld width and higher microstructure uniformity. Autogenous laser welding can achieve the single pass weld penetration at laser keyhole mode. The weld width of narrow-gap laser welded joint was 12.5 mm, which was nearly three times than that of autogenous laser welding. The grain size of autogenous laser welding was obviously smaller and more uniform in depth than that of narrow-gap laser welding. In the weld zone, the coarse columnar α grains grew from the fusion line, while in the heat-affected zone, equiaxed α grains with needle and sawtooth α morphologies were presented. The microhardness of the heat-affected zone was higher than in the weld zone and the base metal due to the denser needle microstructure. The tensile samples all fractured at the base metal, indicating the welded joint strength efficiency was greater than 1.
中等厚度为5至12毫米的钛及钛合金，因其重量轻、强度适中且耐腐蚀，被广泛应用于海洋平台、军事装备及其他领域。在本研究中，对自熔激光焊接和窄间隙激光焊接工艺进行了研究和比较，并分析了焊接特性、焊缝微观结构和接头强度。结果表明，自熔激光焊接效率更高、焊缝宽度更窄且微观结构均匀性更高。自熔激光焊接在激光小孔模式下可实现单道焊缝熔深。窄间隙激光焊接接头的焊缝宽度为12.5毫米，几乎是自熔激光焊接焊缝宽度的三倍。自熔激光焊接的晶粒尺寸明显更小，且在深度方向上比窄间隙激光焊接更均匀。在焊缝区，粗大的柱状α晶粒从熔合线生长，而在热影响区，呈现出具有针状和锯齿状α形态的等轴α晶粒。由于针状微观结构更致密，热影响区的显微硬度高于焊缝区和母材。拉伸试样均在母材处断裂，表明焊接接头强度效率大于1。
