High-strength economical X70 pipeline steel hot-rolling flat plate and production method thereof

Abstract

The invention provides a high-strength economical X70 pipeline steel hot-rolling flat plate and a production method thereof. The high-strength economical X70 pipeline steel hot-rolling flat plate comprises the following chemical components: 0.02-0.08 percent of C, 0.10-0.35 percent of Si, 1.40-1.70 percent of Mn, not more than 0.020 percent of P, not more than 0.005 percent of S, 0.04-0.07 percent of Nb, 0.008-0.030 percent of Ti, 0.02-0.045 percent of Als and the balance of Fe and unavoidable impurities. The production method comprises the steps of smelting, continuous casting and hot rolling and is characterized in that the heating temperature of a hot-rolling plate blank is 1,160-1,280 DEG C; the rough rolling temperature is 1,010-1,150 DEG C, and the finish rolling temperature is 830-950 DEG C; after the plate blank is rolled, the plate blank is subjected to control cooling; the final cooling temperature is 300-600 DEG C, the cooling speed is controlled to be 15-30 DEG C/S, and then the plate is air-cooled to room temperature. The invention has low steel alloy content, no Mo and V, low production cost and high mechanical performance, mouldability and welding performance and is suitable for manufacturing a large-diameter X70 pipeline steel pipe.

Description

technical field [0001] The invention belongs to the technical field of low-carbon micro-alloy steel, and in particular relates to a high-strength economical X70 pipeline steel hot-rolled flat plate for manufacturing high-pressure and large-diameter oil and gas pipelines and a production method thereof. Background technique [0002] Pipeline transportation is the most economical, most convenient and most important transportation method for long-distance transportation of oil and natural gas. In order to reduce the construction investment and operating costs of long-distance oil and gas pipelines and improve transmission efficiency, long-distance oil and gas pipelines are developed in the direction of large diameter and high pressure; in addition, oil and natural gas pipelines are usually located in areas with relatively harsh environments. The medium is complex, which requires pipeline steel to have a series of excellent comprehensive properties such as high strength, high to...

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Problems solved by technology

[0005] The purpose of the present invention is to overcome the problem of high production cost caused by the addition of precious metals Mo, V or strict requirements on the conte

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