Weldability of Ti and Al Dissimilar Metals Using Single-Mode Fiber Laser

Ti and Al have great differences in lattice structure, melting point, heat conductivity, coefficient of linear expansion, etc., and Ti and Al intermetallic compounds such as Ti3Al, TiAl, TiAl3 are easily formed at the contacting surface between Ti and Al. Thus, welding or joining of Ti and Al is considered to be extremely difficult. Nevertheless, in this study, dissimilar welding of Ti and Al using single-mode fiber laser with extremely high welding speed was tried, and the microstructural characteristics of the interface zone in Ti and Al weld were investigated. Especially, full penetration lap welding of Ti and Al was tried with single-mode fiber laser. The strengths of the dissimilar weld were evaluated by the tensile shear test. To recognize the formation of intermetallic phases in the weld fusion zone and the relationship between intermetallic phases and the tensile strength, the lap-welded areas of Ti and Al sheets were observed by scanning electron microscope (SEM) and analyzed by using X-ray diffractometer (XRD). The research results suggest a great formation possibility of a strong Ti/Al dissimilar weld with intermetallic compounds reduced by using a single-mode fiber laser under the condition of an extremely high welding speed.