Effect of laser power on performance of dissimilar joints between Cu-Ni coated low carbon steel and stainless steel

In order to study the effect of laser power on performance of dissimilar lap joints of austenite stainless steel and Cu-Ni coated low carbon steel, Nd:YAG laser with 300W power was used to weld stainless steel and Cu-Ni coated low carbon steel. Optical microscope was adopted to observe the joint and measure the size of weld spot, and universal tensile machine was used to test the bond strength. The results indicate that the size of cross section of weld spot increases with the increase of laser power. The variation of laser power has no influence on the concentration of copper within weld joint which leads to the formation of weld crack. The increasing laser power leads to the transition of laser welding mode from conduction to keyhole. The transition causes the significant growth of weld size and the improvement of bond strength. The research is useful for studying the influence of laser power on laser welding between Cu-Ni coated low carbon steel and stainless steel.