LOW ALLOY STEEL WITH A HIGH YIELD STRENGTH AND HIGH SULPHIDE STRESS CRACKING RESISTANCE.

摘要

A steel contains, by weight: C: 0.2% to 0.5%, Si: 0.1% to 0.5%, Mn: 0.1% to 1%, P: 0.03% or less, S: 0.005% or less, Cr: 0.3% to 1.5%, Mo: 0.3% to 1%, Al: 0.01% to 0.1%, V: 0.1% to 0.5%, Nb: 0.01% to 0.05%, Ti: 0 to 0.01%, W: 0.3% to 1%, N: 0.01% or less, the remainder of the chemical composition of the steel being constituted by Fe and impurities or residuals resulting from or necessary to steel production and casting processes. The steel can be used to produce seamless tubes with a yield strength after heat treatment of 861 MPa or more.