Influence of sulfur on inclusion and pitting resistance of 316L stainless steel

摘要

The effect of the sulfur content on the microstructure and inclusions of 316 L stainless steel was studied by optical microscopy,scanning electron microscopy,and image analysis,and the effect of sulfur on the pitting corrosion resistance of 316 L stainless steel was studied by conducting ferric chloride immersion test and plotting the electrochemical polarization curves.The results show that the added sulfur is mainly in the form of manganese sulfide inclusions in 316 L stainless steel.With increases in the sulfur content,the grade and percentage of the sulfide in the steel gradually increased,and its distribution became increasingly dense.When the sulfur content exceeded0.1%,the number of sulfide inclusions in the sample increased sharply.When the sulfur content reached 0.199%,the sulfides in the steel were primarily in spindle form,and a large number of spindles were found to refine the grain size of 316 L stainless steel.The pitting corrosion weight loss rate of 316 L stainless steel increased with increases in the sulfur content,while the pitting potential gradually decreased.However,the pitting potential of 316 L stainless steel rebounded when the sulfur content reached 0.199%,which may be related to the grain refinement of the test steel and requires further study.