ROUND ROLLED STOCK FROM BORON-CONTAINING STEEL OF INCREASED HARDENING CAPACITY Russian patent published in 2012 - IPC C21D8/06 C22C38/54 C22C38/20 

FIELD: metallurgy.

SUBSTANCE: rolled stock is made from alloyed steel containing the following, wt %: carbon 0.33-0.37, manganese 1.0-1.3, silicon 0.17-0.37, chrome 0.45-0.65, titanium 0.020-0.045, aluminium 0.020-0.045, boron 0.001-0.003, sulphur 0.02-0.04, nickel 0.01-0.30, iron and inevitable impurities are the rest. Steel contains the following components as impurities: phosphorus 0.001-0.030, copper 0.10-0.30, nitrogen 0.001-0.010, molybdenum 0.001-0.08, when the following conditions are met: 40≥C/0.01+B/0.001≥33; 500×[Ti/24-N/7]+0.02≥0; 12/C - Mn/0.055≤20. Rolled stock has ferrite-pearlite fine structure, austenitic grain value of 5, macrostructure as to central porosity, spot non-homogeneity, segregation square of not more than 3 for each type, below-shrinkage segregation of not more than 1, skin holes and intergranular cracks are not allowed, non-metallic inclusions as per sulphides, line oxides, spot oxides, breakable silicates, plastic silicates, unstrained silicates with average value of not more than 3 for each type, hardening capacity - hardness of specimen at end quenching includes the following: at the distance from end surface of specimen of 1.5 mm 52 - 56 HRC; at the distance of 11.0 mm not less than 51 HRC; at the distance of 20.0 mm not less than 45 HRC; at the distance of 40.0 mm 40 to 48 HRC.

EFFECT: creation of rolled stock enlarges the range of consumer properties by increasing hardening capacity properties with simultaneous improvement of properties characterising the structure and purity of rolled stock as per non-metallic inclusions.

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