SECTION IRON HOT-ROLLED MADE OF MICROALLOYED SPRING STEEL Russian patent published in 2008 - IPC C21D8/06 C22C38/60 

FIELD: metallurgy.

SUBSTANCE: invention concerns the metallurgy field. Particularly it concerns manufacturing of bundled rolled or bar metal of gage from 12 to 34 mm for producing gross heavy-loaded springs for various purposes. Rolled metal is obtained from steel, which consists in mass % of: C-(0.56-0.64), Mn-(0.40-0.70), Si-(1.40-1.80), Cr-(0.70-1.20), Ni-(0.005-0.25), V-(0.005-0.20), S-(0.005-0.025), N-(0.005-0.010), As-(0.0001-0.03, Sn-(0.0001-0.02), Pb-(0.0001-0.01), Zn-(0.0001-0.005), iron and inevitable admixtures, provided the implementation of ratio: (As+Sn+Pb+5×Zn)≤0.07; 1.12≤ [C+Si/4+Mn/6+(Cr+V)/5]≤1.50, performed as hot-rolled, hot-calibrated, tempered and drawn. Also it has ferrite-pearlite composition without graphite, martensite, bainite and widmanstatten pattern areas, where effective grain size is 6-12 points, decarbonisated layer depth is not more than 1.5% to the side, macrostructure is: center porosity, spot inhomogeneity, liquating square is not more than 3 points for every kind, undershrinked sweat is not more than 3 points, liquating strip is not more than 1 point, nonmetallic - spot sulphides, spot oxide, stitch oxide, fragile silicate, plastic silicate, unstrained silicate - not more than 2.5 points, average for every kind of impurities, tensile strength is not less than 1470 N/mm², yield strength is not less than 1425 N/mm², δ not less than 6%, ψ not less than 25%.

EFFECT: support of heightened level of consumer behavior.

4 cl, 3 ex