针对12 mm厚超低碳贝氏体(ULCB)钢,采用中小功率CO2激光与气体金属电弧(GMA)复合进行了多层焊接试验。试验结果表明,采用3层焊接,且每层热输入均匀变化时即可获得良好的焊缝成形。焊接过程中,打底焊时激光焦点要严格控制在焊缝坡口钝边金属之内,填充层对激光焦点位置的要求并不严格;为了充分发挥激光的作用,应采用较高的送丝速度。此外,焊缝的拉伸力学性能测试结果表明,超低碳贝氏体钢激光-GMA电弧复合焊接接头的抗拉强度可达到母材的95％以上,甚至部分焊缝超过母材,其平均抗拉强度达到829.5 MPa。当试样断于焊缝时,焊接缺陷是造成焊缝强度下降的主要原因。

Ultra-low carbon bainitic (ULCB) steel plates with 12 mm thickness were welded by using CO2 laser-gas metal arc (GMA) paraxial hybrid process and multipass technique. The experimental results indicated that the good weld can be obtained by controlling the change of heat input on each pass when adopting three passes welding. In hybrid welding process,the focal point position is very important for the first filling pass and should be in the scale of the rootface. For the other filling passes the focal point position could be changed in a large scale. At the same time,in order to increase the utilization of laser energy,the higher wire feeding rate was used. Furthermore,the mechanical property tests showed that the tensile strength of weld in laser-GMA hybrid welding was over 95% as much as that of the base metal,and even to exceed partially the tensile strength of base metal. The tensile strength of the joint is 829.5 MPa when the specimens were failed in base metal. When the specimens were failed in welds,the defects led the specimens to fracture mainly.