Patent ID: 6440236
Filing Date: 2002-08-27
Classification: C21D,C22C

Abstract:
An ultra-high strength metastable austenitic stainless steel:having a chemical composition that comprises, in mass %, not more than 0.15% of C, more than 1.0 to 6.0% of Si, not more than 5.0% of Mn, 4.0-10.0% of Ni, 12.0-18.0% of Cr, not more than 3.5% of Cu, not more than 5.0% of Mo, not more than 0.02% of N, 0.1-0.5% of Ti, and the balance of Fe and unavoidable impurities, satisfies Si+Mo&gE;3.5%, and has a value of Md(N) defined by equation (1) below of 20-140; exhibiting a cold worked multiphase texture composed of 50-95 vol % of martensite phase and the remainder substantially of austenite phase; having a tensile strength of not less than 2200 N/mm2; and having Mo-system precipitates and Ti-system precipitates distributed in the martensite phase; wherein,Md(N)=580-520C-2Si-16Mn-16Cr-23Ni-300N-26Cu-10Mo.