PIPE SHELL MADE OF LOW-ALLOY STEEL Russian patent published in 2008 - IPC C21D8/10 C22C38/60 

FIELD: metallurgy.

SUBSTANCE: invention concerns the metallurgy field. Particularly it concerns manufacturing of pipe shell of diameter from 80 to 180 mm, intended for producing seamless pipe for various purposes. For supporting of heightened level of consumer behavior pipe shell is made from steel which consists in mass % of: C - (0.1-0.20), Mn - (1.0-1.35), Si - (0.15-0.40), V - (0.025-0.080), N - 0.005-0.009, As - (0.0001-0.03), Sn -(0.0001-0.02), Pb - (0.0001-0.01), Zn - (0.0001-0.005), iron and inevitable admixtures, in ratio: As+Sn+Pb+5×Zn≤0.07; [C+(Mn/6+V/5)] ≤0.42. Blank is made as hot-rolled, normalised, has ferrite-pearlite structure, effective grain size is 5-10 points, macrostructure is: center porosity, spot inhomogeneity, liquating square, undershrinked sweat is not more than 2.0 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 3.0 points for every kind. Admixtures: P is not more than 0.025%; S is not more than 0.010%; Cr is not more than 0.20%, Cu is not more than 0.15%; Mo is not more than 0.07%, tensile strength is 400-585 N/mm², yield strength is not less than 220 N/mm², percentage elongation is not less than 30%, impact strength is KCV (+20°C) is not less than 39.2 J/cm².

EFFECT: pipe shell possesses favourable ratio of strength, plasticity and viscosity, mechanical anisotropy floor, low content of nonmetallic, homogeneous macro and microstructure of section iron, heightened hardening characteristics.

4 cl, 2 ex