RU2006146631A - PIPE PROCESSING FROM MICRO-ALLOYED, BORN-CONTAINING STEEL - Google Patents

Claims (4)

A tubular billet of microalloyed boron-containing steel having predetermined parameters of structure, mechanical properties, hardenability, characterized in that the billet is made of steel containing the following ratio of components, wt.%: carbon 0.19-0.23 manganese 0.40-0.90 silicon 0.15-0.30 chromium 0.005-0.60 boron 0.001-0.003 titanium 0.02-0.04 aluminum 0,020-0,040 niobium 0.005-0.02 nitrogen 0.005-0.010 arsenic 0.0001-0.03 tin 0.0001-0.02 lead 0.0001-0.01 zinc 0.0001-0.005 iron and inevitable impurities rest, when performing the following ratios: amount (arsenic + tin + lead + 5 × zinc) ≤0.07; nitrogen / (titanium + 0.5 × aluminum + 10 × boron) ≤0.21, made continuously cast, hot-rolled and thermally improved, has a ferrite-pearlite structure, actual grain size 6–9 points, macrostructure: central porosity, point heterogeneity, segregation square, shrink segregation no more than 2 points for each type, segregation strips no more than 1 point, non-metallic inclusion; sulfides, point oxides, line oxides, brittle silicates, plastic silicates, undeformed silicates not more than 4.0 points for each type of inclusion, mechanical properties after thermal hardening: temporary tensile strength 560-950 N / mm ² , yield strength not less than 420 N / mm ² , yield strength not less than 420 N / mm ² , elongation not less than 20%, relative narrowing not less than 45%, impact strength KCU not less than 30 J / cm ² , hardenability in water (critical diameter) D _cr = 29 mm hardness at 6 mm at end hardening 40 HRC. 2. The tube stock according to claim 1, characterized in that the steel further comprises, as impurities, wt.%: Nickel not more than 0.10; copper no more than 0.10; phosphorus no more than 0.015; sulfur not more than 0.012. 3. The tube stock according to claim 1, characterized in that when the content of manganese is 0.40-0.60%, chromium 0.40-0.60%, it has a temporary tensile strength of 590-950 N / mm ² , the yield strength is not less than 450 N / mm ² , elongation of at least 20%, relative narrowing of at least 50%, impact strength KCU of at least 35 J / cm ² , hardenability in water (critical diameter) D _cr = 29 mm, hardness at 6 mm at end hardening 40 HRC. 4. The tube stock according to claim 1, characterized in that when the content of manganese is 0.60-0.90%, chromium 0.005-0.10%, it has a temporary tensile strength of 560-900 N / mm ² , yield strength of at least 420 N / mm ² , elongation of at least 23%, relative narrowing of at least 45%, impact strength KCU of at least 30 J / mm ² , hardenability in water (critical diameter) D _cr = 23 mm, hardness at 6 mm at the end quenching 40 HRC.