Chang Jinghuan, Cao Rui, Yan Yingjie
State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metal, Lanzhou University of Technology, Lanzhou 730050, China.
Materials (Basel). 2019 Jul 29;12(15):2413. doi: 10.3390/ma12152413.
Cold metal transfer process is applied to join titanium and Q235 steel with copper filler metal. Scanning electron microscope (SEM), energy dispersive spectrometer (EDS) analysis, micro-hardness tests, and tensile strength test were performed to investigate the joining mechanism and strength of joints. The results show that the stacking order of two base metals affected the joining modes and strength. For top Q235 steel to bottom Ti-TA2 lapped joint, there was no distinct interface reaction layer between the steel base metal and the weld metal; dispersed TiFe intermetalics (IMCs) IMCs between the steel base metal and the Ti base metal greatly improved the strength of joint; the tensile force of the joint could reach up to 93% that of steel-steel joint using the same welding parameters. Additionally, the joints were fractured in dimple mode at the steel base metal. For top Ti-TA2 to bottom Q235 steel lapped joint, the increasing volume fraction of Ti-Cu IMCs at the Ti-Cu weld metal interface contributed to the strength of joint degradation. The joints under tensile loading are initiated at the Ti-Cu weld metal interface between the weld metal and Ti base metal, then propagated to weld metal, finally fractured with brittle mode.
采用冷金属过渡工艺，以铜作为填充金属来连接钛和Q235钢。通过扫描电子显微镜（SEM）、能谱仪（EDS）分析、显微硬度测试以及拉伸强度测试来研究接头的连接机制和强度。结果表明，两种母材的堆叠顺序影响接头的连接方式和强度。对于上层为Q235钢、下层为Ti-TA2的搭接接头，钢母材与焊缝金属之间没有明显的界面反应层；钢母材与钛母材之间弥散分布的金属间化合物（IMCs）TiFe极大地提高了接头强度；在相同焊接参数下，该接头的拉伸力可达钢-钢接头拉伸力的93%。此外，接头在钢母材处呈韧窝断裂模式。对于上层为Ti-TA2、下层为Q235钢的搭接接头，Ti-Cu焊缝金属界面处Ti-Cu金属间化合物体积分数的增加导致接头强度降低。拉伸载荷作用下，接头裂纹在焊缝金属与钛母材之间的Ti-Cu焊缝金属界面处萌生，然后扩展至焊缝金属，最终呈脆性断裂。
