Effect of Laser Power on Mechanical and Microstructure Properties of Pulsed Nd:YAG Laser Welded Dissimilar DP600- DP1000 Steel Sheets

Abstract

In the present study, dissimilar dual-phase (DP) steel sheets (DP600-DP1000) were double-sided welded withNd:YAG (Neodymium-doped Yttrium Aluminum Garnet (Y3Al5O12)) laser device and the effect of laser poweron mechanical and microstructural properties of welded sheets was investigated. Laser welds were conductedusing SISMA SWA300 Nd:YAG laser welding machine in the flat position with the butt joint. DP600 and DP1000steels with a 1 mm thickness were selected for the experiments. Laser power was changed from 20% to 75%,and other welding parameters were kept constant. To evaluate the welded samples, tensile, microhardness andoptical microscope tests were performed. As a result of the study, in high laser power values, good quality weldswere obtained. In microstructural studies, it was observed that three different regions were formed in the weldsection; fusion zone (FZ), heat affected zone (HAZ) and base material (BM). These three regions were composedof different phase structures; FZ: martensite, bainite and retained austenite, HAZ: martensite, bainite, ferrite,retained austenite and tempered martensite, BM: ferrite and martensite. Also, different hardness values weremeasured in these different regions, particularly in the FZ highest microhardness values were measured due toeffective martensite formation.