Microcrack formation of iron-based alloys in laser spot welding for photonic packages

The laser welding technique have be applying to joining of photonic packages because of its high precision and productivity. In many cases, stainless steel (SST) and low carbon steel (LCS) are used as the welding materials. There exists solidification crack tendency because of no welding filler and the fast cooling rate. In this study, we present the study of the micro-cracks formation of the joint formed by laser welding. We discuss the failure mechanisms and propose recommendations for avoiding the micro-crack formation of welding SST and LCS system. SEM/EDX, OIM (orientation image microscope) were used in the present study.