HOT-CALIBRATED SECTIONAL IRON MADE OF SPRING STEEL Russian patent published in 2008 - IPC C21D8/06 C22C38/60 

FIELD: metallurgy.

SUBSTANCE: invention concerns metallurgy field. Particularly it concerns manufacturing of sectional iron in rod diameter from 12 till 34 mm for manufacturing springs for rolling stock of rail transport. For providing heightened level of consumer properties for sectional iron is received from steel contained in mass %; C - 0.53-0.58, Mn - 0.60-1.25, Si - 1.40-2.00, Cr - 0.005-0.80, V - 0.005-0.15, S - 0.005-0.015, N - 0.005-0.008, As - 0.0001-0.03, Sn -0.0001-0.03, Pb - 0.0001-0.01, Zn - 0.0001-0.005; iron and unavoidable admixtures - the rest. At ratio: (As+Sn+Pb+5×Zn)≤0.07/2. Admixtures: P is not more than 0.015%, Ni is not more than 0.10, Cu is not more than 0.08, Mo is not more than 0.10, O₂ is not more than 0.002. Hot-rolled, hot-calibrated sectional iron, hardened and tempered allows ferrite-perlitic structure without graphite areas, martensite, bainite and widmanstatten with dimension of actual grain 6-12 grades, decarburised layer depth is not more than 1.5% on the side. Macrostructure: center porosity, point nonuniformity, segregation square not more than 3 grades for every kind, undershrinked liquation not more than 3 grades, segregation streamer not more than 1 grade. Nonmetallics: pointed sulphides, pointed oxides, stitch oxides, fragile silicates, plastic silicates, non-deformed silicates not more than 2,5 average grades for every admixture kind, σ_B not less th 1275 N/mm², σ_T not less than 1177 N/mm², δ not less than 6%, ψ not less than 25%, HB - 241-302.

EFFECT: providing of heightened level of consumer properties for sectional iron.

6 cl, 4 ex