Thick steel material having excellent tensile strength of 450 MPa class having excellent resistance to hydrogen-induced cracking and method for producing the same

摘要

The present invention provides a normalized heat-treated thick steel material having a tensile strength of 450 MPa class and excellent in hydrogen-induced cracking resistance. A thick steel material having a tensile strength of 450 MPa and excellent in resistance to hydrogen-induced cracking and a method for producing the same are provided. The thick steel material of the present invention is, by weight%, C: 0.03 to 0.06%, Si: 0.2 to 0.4%, Mn: 1.0 to 1.6%, P: 0.03. %, S: 0.003% or less, Al: 0.06% or less, N: 0.01% or less, Cu: 0.05 to 0.4%, Ni: 0.05 to 0.5%, Ca : 0.0005 to 0.003%, the balance being a composition of Fe and unavoidable impurities, and a thickness of 40 mm or more. [Selection diagram] Fig. 1