T2铜/304不锈钢激光焊接接头组织及性能研究

Structure and Properties of T2 Copper/304 Stainless Steel Laser Welded Joint

针对铜/不锈钢异种材料激光焊接过程中的物理性能差异较大、冶金相容性较差等问题,利用光学显微镜、扫描电子显微镜、能谱仪,结合拉伸、硬度等试验研究了不同光束偏移量对焊接接头组织及性能的影响。结果表明:焊缝在金属蒸发作用力及马兰戈尼对流效应的共同影响下呈半沙漏状形貌;光束偏向铜侧时,焊缝由于液相分离导致富铁相弥散分布,造成焊缝成分和硬度分布不均匀,熔覆金属中铜的含量较多使得接头强度较低;光束偏向钢侧时焊缝组织为奥氏体和富铜相,焊接接头的强度较高,抗拉强度最高可达240 MPa,与铜母材相当;当光束偏移量为-0.4 mm时,可得到综合性能最优的焊接接头。

The effect of various beam offsets on the microstructure and the properties of welded joints was studied using optical microscope, scanning electron microscope, and energy dispersive spectrometer, combined with tensile and hardness tests to investigate the challenges caused by large differences in physical properties and poor metallurgical compatibility in the laser welding of dissimilar materials such as copper/stainless steel. The results show that the weld is semi-hourglass shaped under the influence of an evaporation force and Marangoni convection effect. When the beam is biased towards the copper side, the iron-rich phase disperses in the weld due to the liquid phase separation, resulting in an uneven distribution of the weld composition and hardness. In addition, the more copper content in the deposited metal, the lower the joint strength. When the beam is biased towards the steel side, the microstructure of the weld is austenite with a copper-rich phase, and the strength of the welded joint increases. Moreover, the maximum tensile strength can reach240 MPa, equivalent to the copper base metal. Therefore, the best comprehensive performance of the welding joint can be obtained when the beam offset is-0. 4 mm.