高强钢的光纤激光焊接性能

为了研究焊接参数对光纤激光焊接熔深和熔宽的影响,采用2 kW光纤激光器对780 MPa高强钢板进行了焊接.研究了离焦量、焊接速度、脉冲频率和峰值功率占比对熔深和熔宽的影响,并对不同焊接速度得到的焊缝组织进行了光学显微镜、SEM和硬度分析.研究表明,在离焦量范围为-5~+1 mm时,随着离焦量的增加,熔深的变化不大,熔宽逐渐减小;焊接速度小于150 mm/min的情况下,熔深和熔宽与焊接速度成反比,而与焊接结合速度成正比;方形波或三角形波激光焊接时,脉冲频率对熔深和熔宽的影响很小.在方形波脉冲激光焊接时,影响焊接熔深的主要因素是暂载率而不是脉冲频率.经研究确定焊缝金属中存在柱状贝氏体(BC)组织.

Fiber laser welding properties of high strength steel

In order to investigate the effect of welding parameters on both welding penetration and width in the fiber laser welding process, a 2 kW fiber laser was used to weld the 780 MPa high strength steel plates. The effect of defocusing distance, welding speed, pulse frequency and peak power ratio on the welding penetration and width was determined, and the microstructure of welding seam obtained at different welding speed was characterized with the optical microscope(OM), scanning electron microscope(SEM)and hardness tester. The results show that in the defocusing distance ranging from -5 mm to +1 mm, the welding penetration has no significant change with increasing the defocusing distance, but the welding width gradually decreases. When the welding speed is lower than 150 mm/s, both welding penetration and width are inversely proportional to the joining speed but in direct proportion to the jointing speed. In both square wave and triangle wave laser welding processes, the pulse frequency has little effect on the welding penetration and width. In the square wave pulse laser welding process, the main factor affecting the welding penetration and width is the duty cycle rather than the pulse frequency. It is confirmed that the columnar bainite(B_C)exists in the weld metal.