HOT-ROLLED SECTION STEEL FROM LAMINATED SPRING STEEL Russian patent published in 2013 - IPC C21D8/06 C22C38/20 C22C38/40 C22C38/58 

FIELD: metallurgy.

SUBSTANCE: hot-rolled section steel is obtained from laminated spring steel, wt %: carbon 0.62 - 0.70, manganese 1.50 - 2.00, silicon 0.60 - 1.00, chrome 0.10 - -0.50, vanadium 0.001 - 0.10, nickel 0.05 - 0.30, phosphorus 0.010-0.035, iron and inevitable impurities are the rest. As inevitable impurities, steel contains sulphur of not more than 0.035 and copper of not more than 0.30. Rolled steel is annealed and has the depth of decarburised layer of not more than 1.5% per side, with the size of austenitic grain of not more than 5 points and with the following macrostructure parameters: central porosity, point non-homogeneity, segregation square, sub-shrinkage segregation of not more than 2 points for each type, with the following mechanical properties after quenching and tempering: ultimate tensile strength of not less than 1275 N/mm², yield strength of not less than 1080 N/mm², relative elongation of not less than 5%, relative constriction of not less than 15%, impact strength KCU of not less than 29 J/cm², and hardness of not more than 229 HB.

EFFECT: improvement of cutting ability; provision of small-grain structure and homogeneous macrostructure.

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