REFRACTORY MARTENSITIC STEEL Russian patent published in 2014 - IPC C22C38/54 

FIELD: metallurgy.

SUBSTANCE: invention relates to refractory martensitic chromic steels used for making the large-diameter forged pieces of high hardness, durability and refractory properties at 650°C and for production of steam pipes and boilers operated at 650°C. Steel contains the following elements, in wt %: carbon 0.015-0.05, silicon 0.10-0.20, manganese 0.45-0.70, chromium 9.10-12.00, nickel ≤ 0.30, tungsten 1.00-1.70, molybdenum 0.65-0.90, vanadium 0.15-0.30, niobium 0.15-0.30, nitrogen 0.025-0.25, boron 0.001-0.003, sulphur ≤ 0.006, phosphorus ≤ 0.008, aluminium 0.001-0.003, copper ≤ 0,30, cobalt 4.00-5.00, zirconium nitride 0.05-0.50, calcium 0.005-0.02, cerium 0.005-0.03, iron making the rest. Zirconium nitride in steel represents nanosized particles.

EFFECT: higher hardness and durability and refractory properties.

2 cl, 3 tbl