Manufacturing High Nitrogen Austenitic Stainless Steels by Pressurized Induction Furnace

Abstract

A 25kg pressurized induction furnace with maximum nitrogen pressure 6MPa was invented to manufacture high nitrogen stainless steels. The suitable process was explored, and the analysis of radiography and macrosegregation of nitrogen of high nitrogen steel ingot was performed. The mechanical properties and inclusions of the forging ingot were also investigated. The suitable solidification nitrogen pressure can effectively prevent the formation of nitrogen porosity and macrosegregation of nitrogen. It is very important to control the purity of the nitrogen gas to a higher level for avoiding the manganese loss and decreasing oxygen content in the steel during the nitrogen gas pressurized melting process. The sound and compact macrostructure high nitrogen austenitic stainless steel with nitrogen content above 1.0 wt % has been manufactured by the pressurized induction melting method. There are mainly nonmetallic inclusions with the size less than 5μm in the HNS-A ingot. The HNS-A exhibits excellent mechanical properties.