Abrégé

The invention relates to a cold-rolled wire made from steel having the following chemical composition, expressed in weight percent: 0.2 = C = 0.6, 0.5 = Mn = 1.0, 0.1 = Si = 0.5, 0.2 = Cr = 1.0, P = 0.020, S = 0.015, N = 0.010, and optionally no more than 0.07% AI, no more than 0.2% Ni, no more than 0.1% Mo, and no more than 0.1% Cu, the remainder being iron and inevitable impurities resulting from production. The wire has a microstructure comprising bainite and optionally up to 35% acicular ferrite and up to 15% perlite. The invention also relates to the production method and to flexible pipes incorporating same that are used for the exploitation of hydrocarbons.

Classes IPC  ?

• C21D 1/18 - DurcissementTrempe avec ou sans revenu ultérieur
• C21D 1/26 - Méthodes de recuit
• C21D 1/30 - Recuit d'homogénéisation pour détruire les tensions internes
• C21D 8/06 - Modification des propriétés physiques par déformation en combinaison avec, ou suivie par, un traitement thermique pendant la fabrication de barres ou de fils
• C21D 9/52 - Traitement thermique, p. ex. recuit, durcissement, trempe ou revenu, adapté à des objets particuliersFours à cet effet pour fils métalliquesTraitement thermique, p. ex. recuit, durcissement, trempe ou revenu, adapté à des objets particuliersFours à cet effet pour bandes métalliques
• C22C 38/00 - Alliages ferreux, p. ex. aciers alliés
• C22C 38/04 - Alliages ferreux, p. ex. aciers alliés contenant du manganèse
• C22C 38/18 - Alliages ferreux, p. ex. aciers alliés contenant du chrome
• C22C 38/22 - Alliages ferreux, p. ex. aciers alliés contenant du chrome et du molybdène ou du tungstène
• C22C 38/40 - Alliages ferreux, p. ex. aciers alliés contenant du chrome et du nickel
• C22C 38/44 - Alliages ferreux, p. ex. aciers alliés contenant du chrome et du nickel et du molybdène ou du tungstène

Abrégé

This profiled wire, of NACE grade, made of low-alloy carbon steel intended to be used in the offshore oil exploitation sector, is characterized in that it has the following chemical composition, expressed in percentages by weight of the total mass: 0.75 < % C < 0.95; 0.30 < % Mn < 0.85; Cr = 0.4%; V = 0.16%; Si = 1.40% and preferably = 0.15%; and optionally no more than 0.06% Al, no more than 0.1% Ni and no more than 0.1% Cu, the balance being iron and the inevitable impurities arising from smelting the metal in the liquid state, and in that the steel is obtained, from hot-rolled rod stock cooled down to room temperature, and then having a diameter of about 5 to 30 mm, by subjecting this starting rod firstly to a thermomechanical treatment comprising two successive steps carried out in order, namely an isothermal quench, giving it a homogeneous perlitic microstructure, followed by a mechanical transformation operation carried out cold with an overall degree of work-hardening (or reduction ratio) of between 50 and 80% at most, so as to give the wire its definitive shape, and in that the profiled wire thus obtained is then subjected to a restoration heat treatment of short duration carried out below Ac1 (preferably between 410 and 710°C), giving it the desired final mechanical properties.

Classes IPC  ?

• C21D 1/20 - Trempe isotherme, p. ex. durcissement bainitique
• C21D 9/52 - Traitement thermique, p. ex. recuit, durcissement, trempe ou revenu, adapté à des objets particuliersFours à cet effet pour fils métalliquesTraitement thermique, p. ex. recuit, durcissement, trempe ou revenu, adapté à des objets particuliersFours à cet effet pour bandes métalliques
• C21D 9/58 - Fours continus pour bandes ou fils métalliques avec chauffage par bains
• C22C 38/02 - Alliages ferreux, p. ex. aciers alliés contenant du silicium
• C22C 38/04 - Alliages ferreux, p. ex. aciers alliés contenant du manganèse