The characteristics and reduction of porosity in high-power laser welds of thick AISI 304 plate

摘要

The porosity produced in the 304 stainless steel laser welds was investigated. The laser welding process was conducted at a laser power of 10 kW. Different welding speeds and shielding gases were used. The porosity in the welds was characterized. The welding processes were observed using a high-speed video camera. The mechanism of the elimination of the porosity was revealed. The suppression of the porosity was made in N-2 rather than Ar or He shielding gases. The porosity was mainly produced at the root and most of the porosity was less than 0.02 mm(3). No significant differences of the metallic plume, liquid melt pool, and laser keyhole were found when Ar or N-2 shielding gas was employed. The solubility of N-2 in the liquid melt pool contributed to the reduction or elimination of the porosity in the 304-L laser welds.