Cold rolled steel wire, method and reinforcement of flexible conduits
AssigneeArcelormittal Wire France
InventorsSylvain Foissey, Gaëlle Bascourt
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Abstract
A cold rolled steel wire having the following chemical composition expressed in percent by weight, 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 not more than 0.07% Al, not more than 0.2% Ni, not more than 0.1% Mo and not more than 0.1% Cu, the balance being iron and the unavoidable impurities due to processing. This wire has a microstructure including bainite and, optionally, up to 35% acicular ferrite and up to 15% pearlite. A fabrication method and flexible conduits for hydrocarbon extraction are also provided.
Claims15
A fabrication method for a cold rolled wire comprising the steps of:
- procuring a hot rolled steel wire rod having a chemical composition comprising, expressed in percent by weight:
- 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%;
- and
- N≤0.010%;
- a balance being iron and the unavoidable impurities due to processing;
- the diameter of said hot rolled steel wire being greater than or equal to 10 mm;
- subjecting the wire rod to an austenitization heat treatment at a temperature greater than 950° C.;
- then
- cooling the wire rod by an isothermal quenching to a temperature that is from 350 to 600° C. to obtain a structure comprising at least 50% bainite and no martensite, and then finishing the cooling to ambient temperature at a cooling rate that is from 30° C./s to 100° C./s;
- and
- subjecting the cooled wire rod to a cold mechanical transformation operation conducted with a total rate of work hardening from 40 to 90% to obtain a mechanical tensile strength Rm of at least 800 MPa.
A fabrication method for a cold rolled wire consisting of the following steps:
- procuring a hot rolled steel wire rod having a chemical composition comprising, expressed in percent by weight:
- 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%;
- and
- N≤0.010%;
- a balance being iron and the unavoidable impurities due to processing;
- the diameter of said hot rolled steel wire being greater than or equal to 10 mm;
- subjecting the wire rod to an austenitization heat treatment at a temperature greater than 950° C.;
- then
- cooling the wire rod by an isothermal quenching to a temperature that is from 350 to 600° C. to obtain a structure comprising at least 50% bainite, no martensite, and optionally up to 35% acicular ferrite and up to 15% pearlite, then finishing the cooling to ambient temperature at a cooling rate that is from 30° C./s to 100° C./s;
- and
- subjecting the cooled wire rod to a cold mechanical transformation operation conducted with a total rate of work hardening from 40 to 90% to obtain a mechanical tensile strength Rm of at least 800 MPa;
- and
- optionally subjecting the wired rod to a stress relief heat treatment.
Dependencies are inferred from the claim text.