TWO-PHASE FERRITIC-MARTENSITIC STAINLESS STEEL AND ITS MANUFACTURING METHOD Russian patent published in 2018 - IPC C22C38/58 C22C38/50 C21D8/02 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, namely to a two-phase ferritic martensitic stainless steel with a martensite phase content of 5 to 95 % by volume, used as a sheet material for the manufacture of freight wagon casings operating in a cold climate. Sheet has chemical composition containing, in mass%: C: 0.005–0.030, N: 0.005–0.030, Si: 0.05–1.00, Mn: 0.05–2.5, P: 0.04 or less, S: 0.02 or less, Al: 0.01–0.15, Cr: 10.0–13.0, Ni: 0.3–5.0, V: 0.005–0.10, Nb: 0.05–0.4, Ti: 0.1 or less, Fe and the inevitable impurities are the rest. For steel sheet components, the following relationships are fulfilled: 10.5≤Cr+1.5×Si≤13.5 and 1.5≤30×(C+N)+Ni+0.5×Mn≤6.0. Sheets are prepared by heating the steel slab to a temperature of 1,100–1,300 °C, hot rolling including hot rolling in which at least one pass is performed with a reduction of 30 % or more in the temperature range above 900 °C, and annealing at a temperature of 700–900 °C for at least one hour.

EFFECT: steel has high corrosion resistance, workability and toughness at low temperatures.

9 cl, 7 dwg, 6 tbl, 3 ex