TUBE STOCK OUT OF ALLOYED MOLYBDENUM CONTAINING STEEL Russian patent published in 2008 - IPC C21D8/10 C22C38/60 

FIELD: metallurgy.

SUBSTANCE: invention refers to production of hot-rolled tube stock of 80-180 mm diameter. To facilitate minimal level of anisotropy of mechanical properties the tube stock is produced out of steel containing the following ratio of elements, wt %: carbon 0.05-0.24, manganese 0.35-0.65, silicon 0.17-0.37, vanadium 0.03-0.08, chromium 0.005-1.10, aluminium 0.020-0.050, molybdenum 0.01-0.030, arsenic 0.0001-0.03, tin 0.0001-0.02, lead 0.0001-0.01, zinc 0.0001-0.005, iron and unavoidable impuruities - the rest at maintaining the ratio: As+Sn+Pb+5×Zn≤0.07. Impurities in wt % contain: nickel not more, than 0.25, copper not more, than 0.25, nitrogen not more, than 0.008, phosphorus not more, than 0.018, sulphur not more, than 0.013. The tube stock is continuous cast and hot-rolled, normalised, it has laminar ferrite-pearlite structure and dimension of actual grain 6-9 points, on macrostructure it has central porosity, pointed non-uniformity, liquation square and sub-shrinking liquation not more, than 2 points in each kind, liquation strips not more, than 1 point, non-metallic inclusions: sulphides, pointed oxides, stripped oxides, fragile silicates, plastic silicates, non-deformed silicates not more than 4.0 points in each kind of inclusions, tensile strength 350-650 N/mm², yield point not less, than 220 N/mm², contraction ratio not less, than 45%, impact resilience not less, than 30 J/cm².

EFFECT: facilitating of minimal level of anisotropy of mechanical properties.

5 cl, 3 ex