A study on effect of laser overlay welding parameters of stainless steel 301 LN: tensile test, microstructure analysis and microhardness evaluation

This study investigates the effects of laser overlay welding parameters on the performance of stainless steel 301 LN. The correlation between welding conditions and material characteristics was explored through systematic experiments involving tensile testing, microstructure analysis and microhardness evaluation. The study reveals that optimizing welding parameters, such as laser power, laser speed and oscillation amplitude, significantly enhances both the mechanical strength and microstructural features of stainless steel 301 LN. The results show the maximum strength was achieved using a power of 3 kW, 2 m/min speed, oscillation amplitude of 1.5 mm and focal position of 6 mm. The microhardness results displayed a significant drop in the centre of the welded zone due to thermal dynamics. Additionally, the findings of fractography results highlighted how minimum and maximum welding parameters affect the fracture characteristics and integrity of welded joints. The study also revealed a complex range of microstructures, including skeletal, vermicular and lathy ferrite formations. The microstructural images provide valuable insights into the size and distribution of lathy ferrites, and the transformation of delta-ferrite to austenite, contributing to a comprehensive understanding of the welding process. Overall, this research contributes to the ongoing efforts to refine manufacturing processes and applications for stainless steel.