CASTING CORROSION-RESISTANT WELDED CRYOGENIC STEEL AND ITS PRODUCTION METHOD Russian patent published in 2022 - IPC C22C38/52 C22C33/04 C21D1/78 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, namely to the production of casting corrosion-resistant welded cryogenic steels, which do not require heat treatment after welding; it can be used in power engineering in the manufacture of complex-profiled casting-welded structures of liquid rocket engines (hereinafter – LRE) with cryogenic fuel components, operating in aggressive media at temperatures from 77 to 293 K. In an induction crucible furnace, steel is melted, containing components at the following ratio, wt.%: carbon up to 0.03, nitrogen 0.03-0.08, chromium 10.5-13.0, nickel 7.5-9.0, molybdenum 0.8-1.5, cobalt 3.0-4.5, vanadium 0.1-0.3, manganese 0.3-0.7, silicon 0.3-0.6, cerium 0.005-0.1, lanthanum 0.005-0.08, calcium 0.001-0.03, tungsten up to 0.2, niobium up to 0.2, titanium up to 0.08, iron is the rest. During steel melting, according to a magnetic sample, a phase composition is adjusted until obtaining at least 95% of martensite in cast metal, the rest is residual austenite. Then, heat treatment is carried out according to a mode of heat stabilization of secondary austenite, including calcination from 1040-1060°C, heating and isothermal exposure at 560-580°C, repeated calcination from 740-760°C, cold treatment at -70°C, and aging at 500°C.

EFFECT: strength characteristics and operational reliability of high-loaded welded structures of cryogenic equipment, used without heat treatment after welding, are increased.

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