A kind of hot-rolled steel strip for ct100 continuous pipe and its production method

Abstract

The invention discloses a hot rolled steel strip for a CT100 level continuous pipe and a production method. The hot rolled steel strip comprises the components of 0.10-0.14wt% of C, 0.10-0.30wt% of Si, 1.10-1.50wt% of Mn, less than or equal to 0.015wt% of P, less than or equal to 0.0020wt% of S, 0.25-0.40wt% of Cu, 0.15-0.35wt% of Ni, 0.60-1.00wt% of Cr, 0.020-0.050wt% of Nb, less than or equal to0.010wt% of V, 0.010-0.030wt% of Ti, less than or equal to 0.0050wt% of N, 0.015-0.060wt% of Al, and 0.0008-0.0025wt% of Ca. The production method comprises the steps that a blank is formed by continuous casting after rotary furnace smelting and other processes are completed; the casting blank is heated; rough rolling is carried out; finish rolling is carried out; and cooling and coiling are carried out. The theoretical working depth can reach 7000 m, the practical working depth is at least increased by 450 m, the underground working pressure reaches 90 MPa, the yield strength of the hot rolled steel strip is greater than or equal to 640 MPa, the tensile strength is greater than or equal to 740 MPa, the whole plate thickness and rigidity fluctuations are less than or equal to 23 HV1.0, the yield ratio is less than or equal to 0.88, the elongation percentage is greater than or equal to 18%, the cross section vickers hardness HV1.0 is less than or equal to 270, the low temperature toughness at minus 20 DEG C is higher than 100 J, and the hot rolled steel strip has no surface copper brittleness tendency.

Description

technical field [0001] The invention relates to a pipeline steel and a production method, belonging to a CT100 grade continuous pipe hot-rolled steel strip with a theoretical operating depth of 7000m and a downhole operating pressure of 90MPa and a production method. Background technique [0002] Coiled tubing is a new type of pipe used in the oil drilling and production industry. The flexible steel pipe with a length of several thousand meters to tens of thousands of meters is coiled on the coil. It is opened from the coil during operation and coiled on the coil again after the operation. use. Compared with traditional oil well tubing, coiled tubing operation is more flexible, and has the advantages of snubbing operation, continuous hoisting, small equipment volume, fast operation cycle and low cost. [0003] Before this invention, there were: [0004] The Chinese patent application number is 201611162208.9, which discloses "a CT90 hot-rolled steel strip for coiled tubing...

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Problems solved by technology

[0005] The Chinese patent application number is 200710168545.3, which discloses "a steel for high plastic coiled tubing and its manufacturing method". Its structure contains part of ferrite and pearlite, which greatly reduces the strength of its steel strip. According to its entire Example, yield strength ≤ 590MPa, tensile strength ≤ 700MPa, too low strength determines that it cannot be used in ultra-deep well operations; in addition, its alloy and design make the surface of its steel strip have the possibility of copper brittleness, which is easy to induce fatigue cracks , which will greatly reduce the fatigue life of the steel pipe, which is also detrimental to the safety of underground operations

[0006] The Chinese patent application number is 200810040895.6, which discloses "a CT90 steel for coiled tubing and its manufacturing method". This is detrimental to the toughness and welding performance of the product; the yield ratio of the steel plate is above 0.90, and the deformability is poor, which cannot meet the requirements of repeated plastic deformation in the operation process of this type of product

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