Austenitic Stainless Steel And Method For Manufacturing Same

Abstract: The present invention provides austenitic stainless steel comprising, by wt%, 0.005-0.03% of C, 0.1-1% of Si, 0.1-2% of Mn, 0.01-0.4 of Cu, 0.01-0.2 of Mo, 6-9% of Ni, 16-19% of Cr, 0.01-0.2% of N, and the remainder of Fe and inevitable impurities, wherein an austenitic stability parameter (ASP) value, as calculated by 551-462(C+N)-9.2Si-8.1Mn-13.7Cr-29(Ni+Cu)-18.5Mo, is 30-60, a [100*N]/[Ni+Cu] value is 1.4 or more, the average size of crystal grains is less than 5 µm, and the fraction (%) of crystal grains having a size of 5 µm or more is less than 10%. The present invention provides a method for manufacturing austenitic stainless steel, the method comprising the steps of: manufacturing a slab by continuously casting austenitic stainless steel, the austenitic stainless steel comprising, by wt%, 0.005-0.03% of C, 0.1-1% of Si, 0.1-2% of Mn, 0.01-0.4 of Cu, 0.01-0.2 of Mo, 6-9% of Ni, 16-19% of Cr, 0.01-0.2% of N, and the remainder of Fe and inevitable impurities, wherein an austenitic stability parameter (ASP) value, as calculated by 551-462(C+N)-9.2Si-8.1Mn-13.7Cr-29(Ni+Cu)-18.5Mo, is 30-60, a [100*N]/[Ni+Cu] value is 1.4 or more, the average size of crystal grains is less than 5 µm, and the fraction (%) of crystal grains having a size of 5 µm or more is less than 10%; hot-rolling and annealing and pickling the slab, followed by cold rolling to a cold reduction rate of 60% or more; and annealing at an annealing temperature in the range of 800-850 °C.

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