The welding of dissimilar metals is one of the available measures to reduce production weight or to save rare metals and a manufacturing cost. To increase the applications of dissimilar metals welding to various fields, superior properties such as excellent corrosive properties and high strength of Ti and low weight and low cost of Al should be utilized. But in the weld fusion zone of Ti and Al, intermetallic compounds such as Ti3Al, TiAl, TiAl2 and TiAl3 are easily formed, and especially, and brittle TiAl2 and TiAl3 make such dissimilar metals joining very difficult. However, it was clarified that an ultra-high speed welding could suppress the formation of intermetallic compounds in the previous study.
Full penetration dissimilar lap welding of Ti and Al with single-mode fiber laser was tried at various high welding speed in this study, and the weld plume and microstructural behavior of the welded zone in the dissimilar Al and Ti weld bead was investigated. To confirm the mechanism of Al and Ti dissimilar laser lap welding, intermetallic compounds in the weld fusion zone and plume behavior during an welding process were observed and analyzed using a scanning electron microscopy, high speed cameras and a spectrometer. Ti3Al intermetallic compound phase existed in all the weld fusion zones produced under any conditions, but the formation areas of such intermetallic compounds could be reduced by the ultra- high welding speed of 50 m/min. It was consequently found that the effect of weld plume on weld fusion zone during high speed laser dissimilar lap welding.