SECTION IRON HOT-CALIBRATED MADE OF 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 hot-calibrated rolled metal of diameter from 12 to 34 mm for producing heavy-loaded springs for various purposes. For supporting of heightened level of consumer behavior rolled metal is obtained from steel which consists in mass % of: C - (055-0.65), Mn - (0.70-1.00), Si -(1.70-2.0), Cr - (0.20-0.40), S - (0.005-0.015), N - (0.005-0.01), As - (0.0001-0.03), Sn - (0.0001-0.02), Pb - (0.0001-0.01), Zn - (0.0001-0.005), iron and inevitable admixtures are the rest, in ratio: (As+Sn+Pb+5×Zn)≤0.07. In the capacity of admixture additionally steel contains: P is not more than 0.020%, Ni is not more than 0.15%, Cu is not more than 0.15%. Hot-calibrated rolled metal 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 for every kind. Mechanical properties after annealing - tensile strength is not more than 850 N/mm², yield strength is not less than 500 N/mm², solidity is 192-269 HB, modulus of elongation is not less than 200000 N/mm², shear modulus is not less than 80000 N/mm².

EFFECT: section iron possesses mechanical anisotropy floor, low inclusion content, homogeneous macro and microstructure.

2 cl, 1 ex