激光焊熔焊区力学性能及热反应区组织结构的变化

Mechanical properties of weld area soldered by lasers and structural changes in hot reaction zone

目的 测试和分析不同激光焊接条件下 3种不同材料的焊接深度、强度和热反应区组织结构的变化。方法 对钴铬合金、镍铬合金、纯钛 3种测试棒采用不同电压和脉冲持续时间焊接 ,与对照组进行比较分析。结果 电压与钴铬合金、镍铬合金的焊接深度和强度呈正比 ,均值为 :2 5 0v时 335MPa～ 330v时 5 73MPa。热反应区晶粒生长小 ,激光束终点呈山峰状 ,中心留有焊接空白区。电压与纯钛的焊接深度呈正比 ,与其强度呈反比 ,均值为 :2 5 0v时 2 2 1MPa～ 330v时 15 4MPa。热反应区晶粒生长较大 ,伴有相变体膨胀、晶间氧化、组织呈蜂窝状改变。结论 激光对钴铬合金、镍铬合金的焊接性能优良 ,但对铸造后的纯钛焊接性能有待进一步探讨。

Objective To analyse and measure the welding depths and strengths of three kinds of welding materials under different laser welding conditions as well as the structural changes of the heat affected zone. Methods Under different voltages and pulse duration three kinds of measuring sticks, including Co Cr alloy, Ni Cr alloy and pure titanium were welded and their strengths were compared with that of control group. At the same time, the structure of the heat affected zone was analysed by means of the gold phase method. Results The welding depth and strength of Co Cr alloy were in direct proportion to the setting voltage, with averages of 335MPa(250V) to 573MPa(330V). At the heat affected zone, the crystal particle was small and the end point of welding by laser bean presented the shape of the mountain peak and the interval of finger shape. The center of measuring sticks had a black zone with the circle shape. The setting voltage was in direct proportion to the welding depth of pure titanium and in inverse proportion to the welding strength with averages of 221MPa(250V) to 154MPa(330V). The crystal particle in the heat affected zone grew large and the solid phase expanded, the interval of the crystal oxidised, and the structure showed honeycomb changes. Conclusion The laser welding is favourable to the welding properties of Co Cr and Ni Cr alloys, but its effect on the welding properties of pure titanium needs further discussion.