Through comparison analysis of the laser weld bonding and laser welding of dual phase steel to aluminum alloy, the adhesive layer action of its effect on dissimilar metals in steel-on-aluminum overlap configuration are discussed. By collecting and analyzing plasma shape and welding spectra, it is found that the color of plasma with high density induced by laser weld bonding is bright, a certain angle is formed between plasma and the sample surface, the surface of aluminum alloy with high reflectivity is improved by the decomposition products of adhesive layer, thus laser energy absorbed by plasma is reduced. However, the relative intensity of spectra and electron density of plasma is increased, which shows that laser energy absorption rate is increased by adding adhesive layer. The adhesive layer also has the effect of increasing weld penetration and width. The result of the shearing experiments shows that the average shear strength of welded joint increases compared to that without adhesive addition. Because of the upper dual phase steel layer with faster cooling rate, and laser energy absorption of the lower aluminum alloy increased, thus the diffusion from the lower Al to the upper steel side is suppressed, the volume fraction of Al on both sides of weld width increase, transverse area of steel and aluminum increase, the bonding rate is improved, in addition, the weld and adhesive layer undertake the shear load together, which can improve the mechanical properties of weld joint with adhesive addition. © 2016 Journal of Mechanical Engineering.
