TUBE STOCK OUT OF ALLOYED NICKEL CONTAINING STEEL Russian patent published in 2008 - IPC C21D8/10 C22C38/60 C22C38/42 

FIELD: metallurgy.

SUBSTANCE: tube stock with diameter from 80 to 180 mm is produced out of alloyed nickel containing steel, containing wt %: C 0.30-0.38, Mn 0.40-0.70, Si 0.15-0.35, V 0.20-0.30, Cr 0.80-1.20, Ni 1.75-2.25, Cu 0.005-0.30, N 0.005-0.015, As 0.0001-0.03, Sn 0.0001-0.02, Pb 0.0001-0.01, Zn 0.0001-0.005, iron and impurities - the rest at following ratio: (As+Sn+Pb+5×Zn)≤0.07, {C+Mn/6+[(Cr+V)]/5+[(Ni+Cu)/15]}≤0.90. As impurities steel contains, wt %: phosphorus not more, than 0.030 and sulphur not more, than 0.030. Tube stock has laminar ferrite-pearlite structure, dimension of the actual grain is 6-9 points, its macrostructure for central porosity, pointed non-uniformity, liquation square, 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 for each kind of inclusions. After normalisation stock possesses tensile strength not less, than 655 H/mm², yield strength not less, than 379-552 H/mm² and specific elongation not less, than 15%.

EFFECT: upgraded level of consumer characteristics; ensuring optimal ratio of hardness, plasticity and viscosity; also minimal level of anisotropy of mechanical properties; low contents of non-metallic inclusions and uniform macro and micro structure of rolled metal.

2 cl, 1 ex