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 with Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet (Y3Al5O12)) laser device and the effect of laser power on mechanical and microstructural properties of welded sheets was investigated. Laser welds were conducted using SISMA SWA300 Nd:YAG laser welding machine in the flat position with the butt joint. DP600 and DP1000 steels 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 and optical microscope tests were performed. As a result of the study, in high laser power values, good quality welds were obtained. In microstructural studies, it was observed that three different regions were formed in the weld section; fusion zone (FZ), heat affected zone (HAZ) and base material (BM). These three regions were composed of 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 were measured in these different regions, particularly in the FZ highest microhardness values were measured due to effective martensite formation.

Keywords

• Pulsed Nd:YAG laser welding,DP600 steel,DP1000 steel,Laser power,Mechanical properties,Microstructure

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