TUBE STOCK OUT OF LOW ALLOYED STEEL Russian patent published in 2008 - IPC C21D8/10 C22C38/14 C22C38/42 

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy, particularly to production of tube stock with diameter from 80 to 160 mm. To upgrade the level of consumer characteristics and facilitate optimal ratio of hardness, plasticity and viscosity a hot rolled tube stock is made out of low alloyed steel, containing elements, wt %: carbon 0.17-0.20, manganese 1.30-1.55, silicon 0.35-0.50, chromium 0.005-0.30, aluminium 0.02-0.06, copper 0.005-0.30, nitrogen 0.005-0.015, arsenic 0.0001-0.03, tin 0.0001-0.02, lead 0.0001-0.01, zinc 0.0001-0.005, iron and unavoidable impurities - the rest at maintaining the following ratio of elements: As+Sn+Pb+5×Zn≤0.07, C+(Mn+Cr+Cu)/20+Si/22+N/60≤0.29, while as unavoidable impurities steel contains, wt %: nickel not more, than 0.03, niobium not more, than 0.020, titanium not more, than 0.030, molybdenum not more, than 0.10, sulphur not more, than 0.015, phosphorus not more, than 0.015. The stock has a laminar ferrite-pearlite structure, the dimension of the actual grain is 6-9 points, for macrostructure: central porosity, pointed non-uniformity, liquation square, sub-shrinking liquation - not more, than 2.0 points for each kind, liquation strips are not more, than 1 point, non metallic inclusions of pointed sulphides, pointed oxides, stripped oxides, fragile silicates, plastic silicates, non deformed silicates are not more, than 5.0 points for each kind of inclusions, tensile strength is 455 N/mm², yield point is not more, than 295^{N/mm2, specific elongation is not less, than 20%.}

EFFECT: production of tube stock with upgraded level of consumer characteristics.

2 cl, 1 ex