X70 pipeline rolling plate for microalloyed resistance weld pipe and production method of X70 pipeline rolling plate

Abstract

The invention discloses an X70 pipeline rolling plate for a microalloyed resistance weld pipe and a production method of the X70 pipeline rolling plate. Steel is prepared from 0.05%-0.09% of C, 0.15%-0.35% of Si, 1.45%-1.70% of Mn, smaller than or equal to 0.015% of P, smaller than or equal to 0.006% of S, 0.040%-0.070% of Nb, 0.005%-0.025% of Ti and the balance iron and inevitable impurities, wherein Al / N is larger than or equal to 4, Mn / C is larger than or equal to 16, Ceq is smaller than or equal to 0.40, and Pcm is smaller than or equal to 0.20. The heating temperature of a casting blank is 1,150-1,250 DEG C, and the holding time is longer than or equal to 150 min; the rough rolling starting temperature is higher than or equal to 1,000 DEG C, and the accumulative reduction of top threepasses is larger than or equal to 50%; the finish rolling starting rolling temperature is 950-1,050 DEG C, the final rolling temperature is 800-900 DEG C, and the accumulative reduction rate of finish rolling top three passes reaches 65% or above; and header centralized cooling is adopted for a laminar flow cooling section, the cooling rate is 15-25 DEG C / s, the coiling temperature is 500-600 DEGC, and then the temperature is air-cooled to room temperature. The toughness is good at the low temperature of -40 DEG C.

Description

technical field [0001] The invention belongs to the field of high-strength low-alloy steel, and in particular relates to a hot-rolled coil of X70 pipeline steel for ERW straight seam electric resistance welded pipe with simple composition design and good comprehensive mechanical properties and a production method thereof. Background technique [0002] As a kind of straight seam welding process, ERW welding process has the advantages of low cost and high efficiency, and is suitable for oil and gas pipelines. [0003] Among the straight seam X70 level patents retrieved, the alloy design contains at least one or more alloying elements besides Nb / Ti, which greatly increases the design cost and also brings certain difficulties and inconveniences to the actual production. [0004] The patent number is ZL201010154675.3, titled "A Steel Plate for Longitudinal Welded Pipe and Its Manufacturing Method", which discloses a rolled steel plate for medium and thick plates, which is formed ...

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Problems solved by technology

[0005] The patent number is ZL201110351541.5, titled "a steel for high-strength corrosion-resistant longitudinal seam welded pipe and its manufacturing method", which discloses a steel for oil casing used in acidic environments. The steel contains V: 0.02% to 0.04 %, Cr: 0.050% ~ 0.075%, Mo: 0.020% ~ 0.030%, Ni: 0.035% ~ 0.050% alloy composition, which increases the manufacturing cost

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