Laser surface alloying of stainless steel with silicon nitride

Abstract

AISI 316L stainless steel was laser surface alloyed with silicon nitride. The effects of the laser surface treatments on the changes of chemical composition, phase, microstructure and hardness were investigated. Energy-dispersive spectroscopy showed that the silicon content in the laser-surface-alloyed layer could reach as high as 9 wt.%. Auger electron spectroscopy also revealed a slight alloying of nitrogen, oxygen and carbon in the surface layer. Ferritic phase was detected in the otherwise austenitic surface layer, and its volume fraction (as revealed by the X-ray diffraction peak intensity) increased with increasing Si content. The Vickers hardness in the laser-surface-alloyed layer varied from 300 to 1200 HV, and was found to be a strong function of Si content.