| 摘要 |
Steel containing, by weight: C: 0.3 to 0.5%, Si: 0.1 to 1%, Mn: 1% or less, P: 0.03% or less, S: 0.005% or less, Cr: 0.3 to 1%, Mo: 1 to 2%, W: 0.3 to 1%,V: 0.03 to 0.25%, Nb: 0.01 to 0.15%, Al: 0.01 to 0.1%, the balance of the chemical composition of the steel consisting of Fe and impurities or residuals resulting from or as a necessary consequence of the smelting and casting processes carried out on the steel. The steel serves for manufacturing weldless pipes for hydrocarbon wells, the yield strength of the steel after heat treatment being equal to or greater than 862 MPa, or even equal to or greater than 965 MPa. |
