钛合金超音频直流脉冲GTAW焊缝组织性能

摘要

Based on butt welding during Ti-6Al-4V（TC4） titanium alloys plate with the thickness of 1.5mm,microstructure of weld face and properties of welded joint were investigated by ultrasonic frequency pulse gas tungsten arc welding（GTAW）.Compared with conventional direct current GTAW process,the experimental results show that ultrasonic frequency pulse current causes the energy concentration with an obvious pinch effect of arc plasma and the increasing escape speed of gas pore.Grain refining and the elimination of gas pore are due to the enhancement of fluid flow by ultrasonic frequency pulse GTAW process for Ti-6Al-4V titanium alloys.The main structure of subcrystal is the basketweave microstructure composed of rod-shaped martensite or the interlaced microstructure composed of both rod-shaped and plate phase.Similarly,ultrasonic frequency pulse GTAW process could also improve the elongation and reduction of area.%基于1.5 mm厚Ti-6Al-4V（TC4）钛合金平板对接试验,研究分析了超音频直流脉冲氩弧焊焊缝金相组织及焊接接头力学性能.结果表明,与常规直流钨极氩弧焊（gas tungsten arc welding,GTAW）相比,由于超音频直流脉冲方波电流的作用,气泡逸出速度增大,Ti-6Al-4V钛合金焊缝的气孔敏感性降低,熔池高温液态金属流动性增强,电弧能量集中,焊缝晶粒细化明显,其亚晶组织以短棒状a＇马氏体组成的网篮状组织或a＇片状组织与短棒状a＇相交织的状态为主,焊接接头断后伸长率和断面收缩率显著提高.