TUBE WORKPIECE FROM ALLOYED STEEL Russian patent published in 2013 - IPC C22C38/48 C21D8/10 

FIELD: metallurgy.

SUBSTANCE: workpiece is made from alloyed steel containing the following, wt %: carbon 0.29 - 0.34, manganese 0.55 - 0.85, silicon 0.17 - 0.37, chrome 0.90 - 1.10, nickel 0.05 - 0.20, aluminium 0.020 - 0.050, copper 0.05 - 0.20, niobium 0.005 - 0.06, vanadium 0.005 - 0.12, molybdenum 0.01 - 0.10, sulphur 0.001 - 0.025; phosphorus 0.001 - 0.025; iron and inevitable impurities are the rest. Steel components meet the following ratio: [C + Mn/6 + (Cr + Mo + V + Nb)/5] ≤ 0.71. Workpiece has maximum values of properties as to macrostructure of up to 2 points for each of the types: central porosity, point non-homogeneity, liquation square, subsurface pinholes to the depth of not more than 2 mm, and content of non-metallic inclusions for each of the types: sulphides, line oxides, non-deformable silicates, point oxides, brittle silicates, ductile silicates is not more than 3.5 points.

EFFECT: increasing homogeneity of rolled stock macrostructure and reducing the content of non-metallic inclusions, which lead to increase in a complex of application properties of rolled stock, as well as providing the possibility of manufacturing pipes with diameter of more than 180 mm at maintaining the above characteristics of homogeneity of macrostructure and content of non-metallic inclusions.

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