PIPE SHELL MADE OF LOW-CARBON LOW-ALLOYED STEEL Russian patent published in 2008 - IPC C21D8/10 C22C38/58 C22C38/60 

FIELD: metallurgy.

SUBSTANCE: invention concerns the metallurgy field. Particularly it concerns manufacturing of pipe shell of diameter from 100 till 180 mm, intended for producing seamless pipe for various purposes. Pipe shell is made of low-carbon low-alloyed steel, which consists in mass % of: C - (0.23÷0.29), Mn - (1.35÷1.65), Si - (0.17÷0.43), Al - (0.02÷0.04), N - (0.005÷0.010), 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; 0.46≤(C+Mn/6)≤0.55. Admixtures: phosphorus is not more than 0.025%, sulphur is not more than 0,030%, chrome is not more than 0.30%, nickel is not more than 0.25%, copper is not more than 0.30%. Pipe blank 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 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 (average point) for every kind. mechanical properties after normalisation - tensile strength is not less than 517 N/mm², yield strength is 379-552 N/mm², percentage elongation is not less than 18%.

EFFECT: heightened level of consumer behavior for pipe shell.

2 cl, 1 ex