Abstract: A steel contains, by weight: C: 0.3% 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: 1.0% to 1.5%, Al: 0.01% to 0.1%, V: 0.03% to 0.06%, Nb: 0.04% to 0.15%, Ti: 0 to 0.015%, 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 enables to produce seamless tubes with a yield strength after heat treatment of 862 MPa or more which are particularly SSC-resistant.

Abstract: The invention concerns steels having excellent resistance over time, in a corrosive atmosphere due to oxidizing environments such as, for example, fumes or water vapor, under high pressure and/or temperature. The invention concerns a steel composition for special applications, said composition containing, by weight, about 1.8 to 11% of chromium (and preferably between about 2.3 and 10% of chromium), less than 1% of silicon, and between 0.20 and 0.45% of manganese. It has been found that it is possible to adjust the contents of the composition based on a predetermined model, selected to obtain substantially optimal properties with respect to corrosion in specific conditions of high temperature performances. Said model can involve as additive of as residue at least one element selected among molybdenum, tungsten, cobalt, and nickel.

Abstract: A steel contains, by weight: C: 0.3% 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: 1.0% to 1.5%, Al: 0.01% to 0.1%, V: 0.03% to 0.06%, Nb: 0.04% to 0.15%, Ti: 0 to 0.015%, 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 enables to produce seamless tubes with a yield strength after heat treatment of 862 MPa or more which are particularly SSC-resistant.

Abstract: The invention concerns steels having excellent resistance over time, in a corrosive atmosphere due to oxidizing environments such as, for example, fumes or water vapour, under high pressure and/or temperature. The invention concerns a steel composition for special applications, said composition containing, by weight, about 1.8 to 11% of chromium (and preferably between about 2.3 and 10% of chromium), less than 1% of silicon, and between 0.20 and 0.45% of manganese. It has been found that it is possible to adjust the contents of the composition based on a predetermined model, selected to obtain substantially optimal properties with respect to corrosion in specific conditions of high temperature performances. Said model can involve as additive of as residue at least one element selected among molybdenum, tungsten, cobalt, and nickel.