HIGH-STRENGTH STEEL PLATE FOR ACID-RESISTANT PIPELINE, AND METHOD OF PRODUCING STEEL PLATE, AND HI

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FIELD : metallurgy. SUBSTANCE : invention relates to metallurgy, namely to high-strength steel plate used for production of acid-resistant pipeline. Plate has a chemical composition containing the following in wt. % : C : from 0.02 to 0.08; Si : from 0.01 to 0.50; Mn : from 0.50 to 1.80; P : from 0.001 to 0.015; S : from 0.0002 to 0.0015; Al : from 0.01 to 0.08; Mo : from 0.01 to 0.50; Ca : from 0.0005 to 0.005; at least one component selected from a group consisting of Nb : 0.005 to 0.1 and Ti : 0.005 to 0.1, optionally at least one component selected from a group consisting of Cu : 0.50 or less, Ni : 0.10 or less, Cr : 0.50 or less, V : from 0.005 to 0.1, Zr : from 0.0005 to 0.02, Mg : from 0.0005 to 0.02 and rare-earth metal : from 0.0005 to 0.02, the rest are Fe and unavoidable impurities. Microstructure of steel at depth of 0.25 mm from the surface of the steel plate is a bainitic microstructure having a dislocation density of 1.0 × 1014 to 7.0 × 1014 (m-2). Vibrations of Vickers hardness at depth of 0.25 mm from the surface of the steel plate make 30 HV or less, and tensile strength is 520 MPa or more. EFFECT : plate has high resistance to hydrogen cracking and high resistance to sulphide corrosion while maintaining high strength, viscosity and weldability. 3 cl, 1 dwg, 2 tbl