Effect of CMT Welding Heat Input on Microstructure and Properties of 2A14 Aluminum Alloy Joint

Cold metal transfer (CMT) welding is an attractive welding technology for thin sheet aluminum alloys because of its low heat input, arc stability and spatter-free behavior during the welding process. The present research is mainly concerned with the effect of different heat input on microstructure and mechanical properties of CMT welding 2A14 aluminum alloy in 3 mm thickness. The results indicate that a welded joint with good quality can be achieved when the welding current is 105 A and welding speed is 8 mm/s. The weld width and porosity gradually increase along with the constantly increasing welding heat input. The center of the welded joint consists of a large number of fine equiaxed dendrites, and the gray matrix is uniformly distributed accompanied by a large number of dots and blocks as a white second phase, corresponding to the composition of the Al2Cu phase. The microhardness of welded joints under different welding heat input maintains relative stability and presents a certain softening degree; the base material is the highest, followed by the heat-affected zone.