SPRING STEEL HAVING ELEVATED HARDENABILITY AND PITTING CORROSION RESISTANCE Russian patent published in 2007 - IPC C22C38/32 C22C38/60 

FIELD: ferrous metallurgy.

SUBSTANCE: invention relates to spring steel, which exhibits excellent hardenability, is liable to lower degree to pitting corrosion under corrosive external conditions, and can possess higher limits of strength and impact elasticity. Spring steel according to invention is composed of, wt %: carbon 0.40-0.70, silicon 0.05-0.50, manganese 0.6-1.00, chromium 1.00-2.00, niobium 0.010-0.050, aluminum 0.005-0.050, nitrogen 0.0045-0.0100, titanium 0.005-0.050, boron 0.0005-0.0060, phosphorus no more than 0.015, sulfur no more than 0.010, iron and inevitable impurities - the rest. When hardened at annealing temperature 400°C, steel is characterized by tensile strength 1700 MPa, hardness at least 49 HRC, and impact elasticity, as measured according to Charpy method, equal to at least 40 J/mm² for a sample with U-shaped cuts 2 mm deep, for which pitting corrosion resistance factor Fce = C%+0.15Mn%+0.41Ni%+0.83Cr%+0.22Mo%+0.63Cu%+0.40V%+1.36Sb%+121B% is at least 1.70.

EFFECT: improved performance characteristics of steel.

3 cl, 3 dwg, 2 tbl, 3 ex