Laser Welding for Dissimilar Metals Stainless Steel AISI 304H, to Low Carbon Steel DIN St33, by Nd: YAG Laser

Abstract

In this research dissimilar welds were made of low carbon steel (DIN St33) 0.5 mm thickness and austenitic stainless steel (304H) 0.5 mm thickness by Nd: YAG laser beam welding (LBW). The effect of laser parameters (i.e peak power and welding speed) on joint strength, microhardness and microstructure has been investigated experimentally. Five level of peak power 5, 5.5, 6, 6.5 and 7 kW respectively, were varied (keeping constant pulse duration 4.7 ms, pulse repition rate 1.5 Hz and welding speed 0.5 mm/sec). For the effect of welding speed five levels of welding speed 0.3, 0.8, 1, 1.3, and 1.5 mm/sec respectively, were varied (keeping constant peak power 5.5 kW, pulse duration 5.2 ms and pulse repition rate 2.8 Hz. The experimental investigation included, tensile shear test, microhardness, microstructure and EDS analysis. It was found that the best welding condition, for maximum joint strength (408N), is 6.5 peak power, it was found for the effect of welding speed, that the best welding condition, for maximum joint strength (433N) is 1 mm/sec. Hardness tests showed that the highest hardness value appears in (WZ).