STEEL Russian patent published in 2014 - IPC C22C38/46 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, and namely to high-quality alloyed structural steels used for manufacture of strength members, gears and shafts, the surfaces of which are strengthened by nitridation. Steel contains the following, wt %: carbon 0.33-0.40, manganese 0.25-0.50, silicone 0.17-0.25, chrome 1.20-1.50, nickel 3.20-3.50, molybdenum 0.35-0.45, vanadium 0.10-0.15, cerium 0.007-0.009, lanthanum 0.001-0.005, aluminium 0.02-0.05, calcium 0.002-0.005, copper ≤0.20, sulphur ≤0.005, phosphorus ≤0.005, and iron is the rest. Ratio of calcium content to aluminium content is 0.13-0.15.

EFFECT: reducing tendency of steel to formation of cracks at forging; improving its hardness penetration; increasing hardness of a nitrated layer at increase of its thickness and at reduction of brittleness.

2 cl, 3 tbl