TC4钛合金微束等离子弧焊接接头疲劳性能研究

Study on fatigue performance of TC4 titanium alloy micro plasma arc welding joint

运用微束等离子弧焊接方法对TC4钛合金薄板进行堆焊,通过测试母材及焊接接头在振动载荷下的疲劳裂纹扩展速率发现,焊接接头的抗裂纹扩展能力比母材强。观察并分析母材及焊接接头的金相组织及疲劳断口可知,焊缝区的网篮组织中存在许多细长α′针状马氏体,会阻碍裂纹的扩展,提高焊缝抗裂纹扩展能力;热影响区组织中的α′针状马氏体比焊缝区数量更多,形态更加短小,是其拥有比焊缝区更好的抗裂纹扩展性能的原因。

In the paper, the micro-plasma arc welding method was used to weld TC4 titanium alloy sheet and test the fatigue crack growth rate of parent metal and welded joint under vibration load. The result showed that the ability to resist crack growth of welded joint was better than the base metal. Though the observation and analysis the microstructure and fatigue fracture of the parent metal and welded joint, it got results that the existence of such many needle type α′ martensite improved the resistance properties to crack propagation in the welded-zone. In the heataffected zone, the α′ martensite was shorter and more complex than those in the welded-zone, which led better propagation resistance than welded-zone material.