ROUND HOT-ROLLED BAR STOCK Russian patent published in 2013 - IPC C21D8/06 C22C38/00 C22C38/18 C22C38/22 

FIELD: metallurgy.

SUBSTANCE: rolled stock is made from steel containing the following, wt %: carbon 0.31-0.34, manganese 0.75-0.95, silicon 0.30-0.45, chrome 0.95-1.10, molybdenum 0.30-0.40, aluminium 0.015-0.045, iron and inevitable impurities, which are represented with the following components, wt %: sulphur of not more than 0.010, copper of not more than 0.20, phosphorus of not more than 0.015, nickel of not more than 0.25, nitrogen of not more than 0.008 is the rest; at that, rolled stock has ultimate strength of not less than 1050 N/mm², yield strength of not less than 950 N/mm², relative elongation of not less than 15%, relative constriction of not less than 55%, impact strength of not less than 111 J/cm², hardness of not more than 255 HB, size of austenitic grain of not more than 6 points, non-metallic inclusions as to oxides and silicates of not more than 4 points, non-deformable silicates of not more than 4.5 points and sulphides of not more than 4 points; at that, rolled stock is subject to heat treatment by heating up to the temperature of 670-690°, exposure during 22 hours, cooling in the furnace to 600°, and then, cooling in still air to the ambient temperature.

EFFECT: providing high mechanical properties of hot-rolled stock.

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