RU2006146620A - PIPE PROCESSING FROM MICROALLOYED STEEL - Google Patents

Claims (2)

1. A tubular billet of microalloyed steel, continuously cast, hot rolled, having predetermined parameters of non-metallic inclusions, actual grain size, mechanical properties, macrostructure, characterized in that the steel contains the following ratio of components, wt.%: carbon 0.16-0.27 manganese 0.34-1.00 silicon 0.17-0.37 chromium 0.005-0.20 molybdenum 0.001-0.10 copper 0.005-0.20 nickel 0.005-0.20 nitrogen 0.005-0.008 niobium 0.005-0.010 vanadium 0.005-0.020 titanium 0.005-0.040 iron and inevitable impurities  rest, subject to the following conditions: V + Nb≤0.02; C + Mn / 6 + (Cr + Mo + V) / 5 + (Ni + Cu) / 15≤0.43 the pipe billet has a ferrite-pearlite structure, the actual grain size is 5-8 points, for the macrostructure: central porosity, point heterogeneity, segregation square, shrink segregation no more than 2 points for each species, segregation strips no more than 1 point, for non-metallic sulfide inclusions , point oxides, line oxides, brittle silicates, plastic silicates, undeformed silicates not more than 2.5 points for each type of inclusions, mechanical properties after normalization: temporary tensile strength not m She 415 N / mm ^2, yield stress of not less than 241 N / mm ^2, an elongation of at least 24%. 2. The pipe billet according to claim 1, characterized in that, as unavoidable impurities, the steel additionally contains the following components, wt.%: Aluminum, not more than 0.050, sulfur, not more than 0.025, phosphorus, not more than 0.025.