Microstructural Evolution and Hardness Profile of High Nitrogen Austenitic Steel After Arc-laser Hybrid Welding

Abstract

An arc-laser hybrid welding was performed on high nitrogen austenitic steel which was used in the industries. Micro-vickers hardness tester, Optical microscopy, secondary and backscattered electron beam image analysis, image analyzer and Energy Dispersive X-ray Spectroscopy (EDS) in Scanning Electron Microscopy (SEM) were applied to reveal the microstructural details. The results indicate that, the microstructures of the weld bead are consisted of the dendrite-like austenitic phase and the small rod-like delta ferritic phase located between the dendrites. The solidification mode of the bead is AF mode. The grain size in heat affected zone (HAZ) is larger than the parent metal, and the near the bead area, the larger the size of the grain.