RESEARCH ON CHARACTERISTICS OF WELDING FOR Al/Ti DISSIMILAR ALLOYS WITH TRAILING ULTRASONIC

In this dissertation, Tungsten Inert Gas Welding (TIG) between Ti-6Al-4V and AlMg6 was conducted by using 380 filler metal by the condition of different parameters, welding technology, and the ambiance was full of Ar gas. Formation of intermetallic was controlled effectively with changing welding parameters of metal flush, and using of ultrasonic oscillating obtained favorable weld line. Hybrid characteristic of welding and brazing joint were obtained. The difficulty of burning question during Al to Ti was solved. The parameter rules of influence on weld appear, interfacial reaction and mechanical properties were clarified. It provided a foundation for controlling joint quality. Microstructure characteristics of Al/Ti joints had been analyzed by optical microscopy, SEM, ED. Joint strength was measured via tensile test. The results showed that an intermetallic compound layer had formed at the brazing interface between mixed seam metal and titanium. The intermetallic compound layer at interfacial top includes an acicular Ti-Al-Si intermetallic layer and a continuous Ti-Al intermetallic layer nearby titanium alloy. The microstrcture can be improved by using of ultrasonic oscillating, and it made the mechanical properties better than before. According to the research on the characteristics relation of interfacial reaction layer growth, the interfacial reaction layer growth and preventing formation of intermetallic layer growth was controlled by using of ultrasonic oscillating. The problems of the joining of Al to Ti was restrained, and the optimized mechanical welding parameters was obtained. The results provides a academic basis for Al/Ti dissimilar alloying.