电压对金合金与钴铬合金激光焊接效果的影响

目的探讨不同电压对金合金与钴铬合金焊接效果的影响。方法按GB228标准制作金合金、钴铬合金原始试件，于中点处垂直长轴切断，保持脉冲持续时间4ms、光斑直径0．8mm，光斑重叠率75％，激光频率1Hz，分别在340V、360V、380V的电压下进行激光焊接，金合金和钻铬合金母材为对照组。每组1件试件，以3mm／min的拉伸速度进行拉伸试验，扫描电镜观察断裂试件的断裂面。结果340V未焊透，360V组与380V组均焊透。扫描电镜观察发现，钻铬合金对照组断口为解理断裂，金合金对照组断口为韧性断裂。3组实验组试件的断面均出现韧性断裂、解理断裂和沿晶断裂3种断裂，呈现以脆性断裂为主的混合断裂方式。当焊接电压为340V时，拉伸断面大部分呈脆性断裂特征。当焊接电压为360V时，断裂区有较多的韧窝状结构，仅有微量气孔，当焊接电压为380V时，金属过度融化甚至气化，气孔的量增多。韧性断裂区域面积比360V组（21．72％）明显大于380V组（7．41％），而沿晶断裂所占比例360V组（37．42％）明显小于380V（52．73％）。结论在脉冲持续时间4ms、光斑直径0．8ram，光斑重叠率75％，激光频率1Hz，360V的电压焊接参数下激光焊接钴铬合金、金合金可以获得较好的焊接效果。

Effect of voltage on the laser welding results of CoCr alloy and gold alloy

Objective To investigate the effect of voltage on the laser welding results of CoCr alloy and gold alloy. Methods CoCr alloy and gold alloy original specimens were prepared and cut through at the middle point perpendicular to the long axis. The two alloys were welded together by laser under the voltage of 340V, 360V and 380V, respectively,and under the same pulse duration 4 ms, spot diameter 0. 8mm, flare overlap rate 75% and laser frequency 1Hz. CoCr alloy and gold alloy served as control group. Tensile test was performed at a speed of 3mm/min. The microstructure and metallographic structure of the fractured surface were observed by electron microscope. Results 360V and 380V groups showed complete welding, 340V group did not. CoCr alloy was cleavage fracture and gold alloy ductile rupture. The experimental groups all exhibited three different fracture surface, cleavage fracture, ductile rupture, intergranular fracture. 360V group had a larger percentage of ductile rupture and smaller percentage intergranular fracture. Conclusion Good welding results between CoCr alloy and gold alloy could be obtained under the voltage of 360V,oulse duration 4 ms and soot diameter 0. 8mm.