RU2006131204A - TUBING OF CHROME STEEL, ENHANCED CUTTING - Google Patents

Claims (2)

1. Tubular billet made of chrome steel, having non-metallic inclusions in the form of globular sulfides with an oxysulfide shell, the specified parameters of the structure, mechanical properties, characterized in that the billet is made of steel containing the following ratio of components in wt.%: carbon [C] 0.12-0.17 Manganese [Mn] 0.30-0.60 silicon [Si] 0.17-0.37 chrome [Cr] 0.30-0.60 sulfur [S] 025-0.035 nitrogen [N] 0.005-0.010 calcium [Ca] 0.001-0.006 arsenic [As] 0.0001-0.03 tin [Sn] 0.0001-0.02 lead [Pb] 0.0001-0.01 zinc [Zn] 0.0001-0.005 iron and inevitable impurities rest, when the relations amount (arsenic + tin + lead + 5 · zinc) ≤0.07; (calcium / sulfur) ≥0.055, hot rolled, heat-treated and turned, the workpiece has a ferritic perlite structure, the actual grain size is 5-10 points, the macrostructure is central porosity, point heterogeneity, segregation square, shrink segregation no more than 3 points for each type, segregation strips no more than 1 point, non-metallic inclusions — point sulfides, point oxides, line oxides, brittle silicates, plastic silicates, undeformed silicates no more than 4.5 points for each type of inclusion, mechanical Twa after quenching and tempering - tensile strength of not less than 687 N / mm ^2, yield stress of not less than 491 N / mm ^2, an elongation of at least 12%, relative narrowing of at least 45%, the toughness of not less than 78.4 J / mm ² and increased machinability. 2. The tube stock according to claim 1, characterized in that the steel further comprises, as impurities, wt.%: Phosphorus no more than 0.0350, nickel no more than 0.25, copper no more than 0.30.