Microstructure and properties of T2 copper/304 stainless steel laser brazed joint

Laser welder was used to weld T2 copper and 304 stainless steel with Cu-Mn-Ni brazing filler metal. Macroscopic morphology of brazed seam, mechanical properties of brazed joints and element diffusion of brazing filler metal were tested and analyzed by scanning electron microscope and tensile testing machine. The results showed that the influence of welding current on formation of brazed seam was the largest,the pulse frequency was second, and the pulse width was the least in laser brazing copper/stainless steel. The corresponding orthogonal test range were 17.35, 15.66 and 7.91, respectively. Good diffusion and solid solution were formed between the brazing filler metal and the base metal. Fe and Cr elements in the weld bead diffused obviously and there existed granular copper-based solid solutions. Under the optimal brazing parameters, shear strength of brazed joints reached 35.75 MPa.