Correlation of high power laser welding parameters with real weld geometry and microstructure

Abstract

High power laser welding has exhibited tremendous advantages over traditional arc or plasma welding over last decades. However, there still exist microstructural heterogeneity in fusion zones (FZ) and heat affected zones (HAZ), as well as loosening of the grain boundary and structural defects, which would lead to the mechanical property discontinuity of whole welded components and eventually affect the service performances. In this paper, the effect of welding parameters on the weld shape, microstructure, element distribution and texture evolution was studied under high power laser ranging from 5kW to 9kW on 7mm thickness plates of SUS201 with bead-on-plate configuration. The results show that single variations of welding parameters could result in great changes of weld transverse profiles and three typical shapes of welds, including the Peanut-shaped welds (PWs), Nail-shaped welds (NWs) and Wedge-shaped welds (WWs), were summarized out according to the self-established shape factors. Relationships between welding parameters with weld shapes were preliminarily established with the help of optical microscopy (OM) and correlations between typical weld shapes with the distribution & morphology of microstructures were also explored quantitatively by SEM and EBSD tests.