Laser brazing of a dissimilar joint of austenitic stainless steel and pure copper

Abstract

In many industries, there are applications that require the joining of stainless steel and copper components; therefore, the welding of dissimilar stainless steel/copper joints is a common process. For this investigation, the optimal brazing conditions and suitable filler metals for laser brazing of stainless steel/copper lap joints were studied. Tensile shear force increases with increases in the laser spot diameter or in the laser irradiation angle, which is associated with increased bonding width; however, as bonding width approaches 2 mm, tensile shear force reaches a saturated value due to fracturing at the HAZ of the Cu base plate. In order to obtain joints with high tensile shear strength, laser brazing was optimized by using Cu -Sibased filler metal under the following conditions: laser power, 4 kW; spot diameter, 3 mm; laser irradiation angle, 808; irradiation position shift, 0.6 mm; brazing speed, 0.30 m/min; and filler metal feed speed, 0.30 min. Concerning filler metals, it was found that the Ni -Cu type showed relatively large tensile shear force even at high welding speeds in comparison with those of the Cu-Si, Cu, Cu-Ni, Ni -Cu and Ni types, respectively.