TUBE STOCK OUT OF ALLOYED HEAT RESISTANT STEEL Russian patent published in 2008 - IPC C21D8/10 C22C38/60 C22C38/48 

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy, particularly to production of tube stock with diameter from 80 to 180 mm. To facilitate upgraded level of consumer characteristics at a minimal level of anisotropy of mechanical properties the tube stock is fabricated out of steel, containing, wt %: carbon 0.22-0.28, manganese 0.50-0.70, silicon 0.17-0.37, chromium 0.80-1.10, nickel 0.005-0.25, molybdenum 0.15-0.25, vanadium 0.06-0.11, niobium 0.03-0.06, titanium 0.01-0.03, aluminium 0.020-0.05, copper 0.005-0.025, sulphur 0.005-0.013, nitrogen 0.005-0.008, calcium 0.001-0.005, 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 ratio: Ca/S≥0.1; As+Sn+Pb+5×Zn≤0.05; C+Mn/6+(Cr+Mo+V+Nb)/5+(Ni+Cu)/15≤0.70. The tube stock has a laminar ferrite-pearlite structure with the dimension of the actual grain of 6-9 points. It also has macrostructure for central porosity, pointed non-uniformity, liquation square and sub-shrinking liquation not more, than 3 points for each kind, and liquation strips - not more, than 2 points. Non-metallic inclusions for sulphides, pointed oxides, stripped oxides, fragile silicates, plastic silicates, non-deformed silicates consist not more, than 4 points in each kind, tensile strength is not less, than 685 N/mm², yield point is not less, than 490 N/mm², specific elongation is not less, than 12%, contraction ratio is not less, than 35%. As impurities steel contains wt. %: phosphorus not more, than 0.015 and hydrogen not more, than 0.000002 (2ppm).

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

2 cl, 1 ex