SECTION IRON MADE OF MEDIUM-CARBON STEEL FOR COLD FORGING Russian patent published in 2008 - IPC C21D8/06 C22C38/60 

FIELD: metallurgy.

SUBSTANCE: invention concerns the metallurgy field. Particularly it concerns manufacturing of section iron, round, of diameter from 12 to 34 mm. Round section iron is obtained from steel which consists in mass % of: C - 0.42-0.45, Mn - 0.5 0-0.80, Si - 0.17-0.37, Cr -0.01-0.25, S - 0.005-0.035, P - 0.005-0.035, Ca - 0.001-0.010, N - 0.005-0.015, O₂ 0.001-0.015, 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; (S+P)≤ 0,060; O₂/Ca=1÷4.5; admixtures mass %: nickel is not more than 0.25, copper is not more than 0.25. Section iron has average maximal point of pollution by nonmetallic: spot sulphides, spot oxide, stitch oxide, fragile silicate, plastic silicate, unstrained silicate not more than 3.5 points for every kind, fine-dispersed ferrite-pearlite structure, effective grain size is 5-9 points, 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, σ_"в" - not more than 610 MPA, δ - not less than 15%, ψ- not less than 40%, a_H KCU(+20) - not less than 2000 kJ/m². Cutability, magnitude of wear by back edge of tool h₃ is not more than 0.40 mm at equal path of cutting L=1320 m, value of cold yielding is not less than 1/3 of height.

EFFECT: support of heightened features of technological plasticity and low level of strain strengthening.

4 cl, 2 ex