UNSTABILIZED AUSTENITIC STEEL RESISTANT TO LOCAL CORROSION IN SCP-WATER Russian patent published in 2023 - IPC C22C38/58 

FIELD: metallurgy.

SUBSTANCE: invention relates to unstabilised high-strength corrosion-resistant austenitic steels used in the manufacture of elements of nuclear power units operating under supercritical pressure (SCP) coolant in contact with water at temperatures up to 580°C. The steel contains, wt.%: carbon not more than 0.04, silicon 1.2-1.9, manganese from more than 3.0 to 5.0, chromium from more than 25.0 to 28.0, nickel 20.0-23.0, molybdenum 2.0-2.5, nitrogen 0.10-0.21, vanadium 0.02-0.12, tungsten 0.10-0.20, boron 0.0005-0.008, calcium 0.001-0.015, cerium 0.001-0.005, iron and the rest is inevitable impurities. For steel components, the following ratio holds: (1.5[Cr]+1.2[Mn]+1.1[Mo]+2.4[V]+0.5[W]-1.7[Si]-1.2[Ni]-2.3[B])/([N]+[C])≥90 and ([Cr]+[Mo]+1.5[Si]+0.5[W]+[V])/([Ni]+0.5[Mn]+30[N]+30[C ])≤ 1.10. After heating for 2000 hours at 580°C the thermal stability of steel is provided, its resistance to sensitization and sigmatization of the structure, to intergranular and pitting corrosion, cracking in a chloride-containing environment, while increasing strength and maintaining ductility.

EFFECT: thermal stability of steel.

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