Metallurgical investigations of pulsed Nd:YAG laser welding of AISI 321 and AISI 630 stainless steels

In this paper, pulsed Nd:YAG laser welding of 321 austenitic stainless steel and 630 (17-4PH) precipitation hardening stainless steel is being studied. The joints had a circular geometry and butt welded. Studies were focused on the effects of laser power, beam diameter and pulse duration on the depth and width of the welds. Microstructures of the welded joints were investigated by optical and scanning electron microscopy. The results show that both weld depth and weld width increase with voltage. In addition, the pulse duration have bilateral effects on the weld bead depth and width. Very fine cellular and dendritic structures were achieved in the weld zone. The martensitic microstructure was achieved in the weld metal adjacent to the AISI 630 side and austenitic-ferritic microstructure was obtained near the AISI 321 side. The microhardness tests showed that the maximum hardness was produced for the 630 stainless steel side and the minimum hardness was occurred for the 321 stainless steel side.