PIPE SHELL MADE OF MEDIUM-CARBON 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 90 to 180 mm, intended for producing seamless pipe for various purposes. Pipe shall is made from steel, which consists in mass % of: C (0.31-0.34), Mn (0.55-0.95), Si (0.20-0.35), Cr (0.80-1.10), Ni (0.005-0.50), Mo (0.15-0.65), Al (0.015-0.05), S (0.001-0.020), P (0.005-0.020), N (0.005-0.012), 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; 0.60≤(C+Mn/6+(Cr+Mo)/5)≤0.82, hot-rolled and improved, and has ferrite-pearlite structure, effective grain size is 5-10 points, macrostructure is: center porosity, spot inhomogeneity, liquating square is not more than 2 points, undershrinked sweat is not more than 1 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, tensile strength is 570-840 N/mm², yield strength is not less than 420 N/mm², percentage elongation is not less than 18%, impact strength KCV (+20°C) is not less than 38.0 J/cm². In capacity of admixture steel also contains copper - not more than 0.25%.

EFFECT: supporting of heightened level of consumer behavior for pipe shell.

5 cl, 3 ex