Steel Material Suitable For Use In Sour Environment

Abstract: Provided is a steel material having high yield strength, excellent low-temperature toughness, and excellent SSC resistance. The steel material according to the present disclosure has a chemical composition described in the specification, has a yield strength of 862 MPa or more, and satisfies expressions (1) to (4). In the steel material, the number density NDF of precipitates having a circle-equivalent diameter of 20-150 nm is 0.650/µm2 or more, and the number density NDC of precipitates having a circle-equivalent diameter of 250 nm or more is 0.290/µm2 or less. (1): (0.157 x C-0.0006 x Cr-0.0098 x Mo-0.0482 x V+0.0006)/?Cr=0.300 (2): (1+263 x C-Cr-16 x Mo-80 x V)/(98-358 x C+159 x Cr+15 x Mo+96 x V)=0.355 (3): -9.7 x Mn-104 x S+0.8 x Mo+0.08 x Ni2-4.1 x Ni-5.1 x Ti=-9.0 (4): 15.8 x Si-33.8 x Mn-28.8 x Ni=-51.0

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