超声跨态处理对TC4钛合金激光焊缝组织与硬度的影响

Effect of Ultrasonic Vibration on Microstructure and Hardness of TC4 Titanium Alloy Laser Welding Joints

为改善TC4钛合金激光焊接质量,引进超声振动场辅助激光焊接工艺(超声跨态处理,UPPLW),通过改变超声场强度的方法,研究超声功率对接头宏观形貌、微观组织以及显微硬度的影响。结果表明,在辅加超声场作用下,随着超声功率的增加,焊缝表面出现团簇状凹坑且表面粗糙度降低;α′相针状马氏体含量更加密集,取向和排列更加杂乱,针状组织的平均长度因超声振动和辐射压力的作用而变短;焊缝区域的显微硬度增大,热影响区和母材区域的显微硬度基本保持不变。

In order to improve the laser welding quality of TC4 titanium alloy, ultrasonic processing across different phases based on laser welding was introduced to assist laser welding, and the effects of ultrasonic vibration field on the macromorphologies, microstructures and microhardness of the laser welding joints were studied by changing the ultrasonic vibration power. The results show that under the effect of the ultrasonic vibration field, with the increase of ultrasonic vibration power, clumped concaves appear on the welding surface, and the surface roughness of the welding joints is lower; meanwhile, the acicular α′-martensite content is more intense, and its orientation and arrangement are more cluttered; besides, the acicular α′-martensite average length is shorter because of ultrasonic vibration and radiation pressure. The microhardness of welding joints increases, but the microhardness of heat affected zone and the base metal area remain unchanged with the increase of ultrasonic vibration power.