Austenitic Stainless steel with High Mn and N

摘要

An austenitic stainless steel with high contents of Mn and N is provided to suppress generation of nitrogen pores using a numerical formula considering the degree of influence of nitrogen and formation behavior of delta ferrite on solid solubility in steel by reciprocally controlling compositions ratios of alloy elements. An austenitic stainless steel with high contents of Mn and N comprises, by weight percent, 0.15% or less of C, 1.0% or less of Si, 5 to 12% of Mn, 8.0% or less of Ni, 14.0 to 23.0% of Cr, 0.40% or less of N and 3.0% or less of Cu with the balance being Fe and other unavoidable elements, wherein constituents of an alloy is controlled such that a ratio of a Cr equivalent(Creq.) to a Ni equivalent(Nieq.) and an excess nitrogen index(Ex.N) satisfy the following numerical formula: A1ÎEx.N+A2ÎCreq.=1(A1:0.2351, A2:0.4015). The excess nitrogen index satisfies the following numerical formula: Ex.N={N/(Cr+0.5Mn-C-0.5Si-0.05Ni)}Î100. The Ni equivalent and the Cr equivalent satisfy the following numerical formulas: Nieq.(Ni equivalent)=Ni+0.25Mn+15N+25C+0.35Cu, and Creq.(Cr equivalent)=Cr+0.7Si.