Abstract: Assembled submarine hull steel components, each steel component having a chemical composition consisting of, in weight percent: 0.030%?C<0.080% 0.040%?Si?0.13% 0.1%?Mn?1.4% 2%?Ni?4% Cr?0.3% 0.30%?Mo+W/2+3(V+Nb/2+Ta/4)?0.89% 0.15%?Mo?0.89% V+Nb/2+Ta/4?0.004% Nb?0.004% Cu?0.45% Al?0.1% Ti?0.04% N?0.0300% impurities resulting from the production operation, said impurities including B?0.0005%, P+S?0.015%, the balance being iron, the chemical composition complying with the condition: 410?540×C0.25+245[Mo+W/2+3(V+Nb/2+Ta/4)]0.30?460.

Abstract: Assembled submarine hull steel components, each steel component having a chemical composition consisting of, in weight percent: 0.030%?C<0.080% 0.040%?Si?0.13% 0.1%?Mn?1.4% 2%?Ni?4% Cr?0.3% 0.30%?Mo+W/2+3(V+Nb/2+Ta/4)?0.89% 0.15%?Mo?0.89% V+Nb/2+Ta/4?0.004% Nb?0.004% Cu?0.45% Al?0.1% Ti?0.04% N?0.0300% impurities resulting from the production operation, said impurities including B?0.0005%, P+S?0.015%, the balance being iron, the chemical composition complying with the condition: 410?540×C0.25+245[Mo+W/2+3(V+Nb/2+Ta/4)]0.30?460.

Abstract: The invention relates to a steel for the production of submarine hulls having the chemical composition: 0.030%?C<0.080% 0.040%?Si?0.48% 0.1%?Mn?1.4% 2%?Ni?4% Cr?0.3% 0.30%?Mo+W/2+3(V+Nb/2+Ta/4)?0.89% Mo?0.15% V+Nb/2+Ta/4?0.004% Nb?0.004% Cu?0.45% Al?0.1% Ti?0.04% N?0.0300% the balance being iron and impurities resulting from the production operation, boron being an impurity whose content is less than 0.0005%, and P+S?0.015%, the chemical composition complying with the condition: 410?540×C0.25+245[Mo+W/2+3(V+Nb/2+Ta/4)]0.30?460.

Abstract: The invention relates to a steel for the production of submarine hulls, which is characterised in that the chemical composition thereof comprises, by weight percent: 0.03%?C<0.08%; 0.04%?Si?0.48%; 0.1%?Mn?1.4%; 2%?Ni?4%; Cr?0.3%; 0.3%?Mo+W/2+3(V+Nb/2+Ta/4)?0.89%; Mo?0.15%; V+Nb/2+Ta/4?0.004%; Nb?0.004%; Cu?0.45%; Al?0.1%; Ti?0.04%; N?0.03%; the remainder comprising iron and impurities resulting from production, boron being an impurity with a concentration of less than 0.0005% and P+S?0.015%, the chemical composition satisfying condition 410?540×C0.25+245[Mo+W/2+3(V+Nb/2+Ta/4)]0.30?460. The inventive steel has an essentially martensitic or lower bainitic structure comprising at least 90% martensite or lower bainite, at most 5% residual austenite, at most 5% ferrite. The steel has a yield strength of between 480 MPa and 620 Mpa and a Charpy toughness V, KCV at ?60° C. of more than 50 J.