Thick-gauge x80 pipeline steel plate with excellent ultra-low temperature drop weight performance and manufacturing method thereof

Abstract

The invention discloses a thick-specification X80 pipeline steel plate excellent in ultralow-temperature drop hammer performance. The thick-specification X80 pipeline steel plate comprises, by mass, 0.02%-0.06% of C, 1.45%-1.6% of Mn, 0.1-0.35% of Si, 0-0.0006% of S, 0-0.010% of P, 0.055%-0.08% of Nb, 0.008%-0.03% of Ti, 0-0.008% of V, 0-0.06% of Alt, 0-0.0040% of N, 0-0.004% of O, 0-0.30% of Mo, 0-0.0015% of Pb, 0-0.003% of Zn, 0-0.0015% of Sb, 0-0.0015% of Sn, 0-0.30% of Cu, 0.20%-1.5% of Ni, 0-0.35% of Cr, 0-0.01% of Ca, the balance Fe and inevitable impurity elements, and the sum of the Mo, the Cu, the Ni and the Cr is less than or equal to 1.5%. The thickness of the steel plate is 30 mm or above. The manufacturing process of the thick-specification X80 pipeline steel plate comprises the following steps of proportional material preparing, converter or electric furnace smelting, external refining, continuous casting, plate blank reheating, conducting of specific TMCP technology, stack cooling after cooling and strengthening. According to the thick-specification X80 pipeline steel plate excellent in the ultralow-temperature drop hammer performance and the manufacturing process, the low-temperature toughness of the X80 pipeline steel plate is further improved, especially, the ultralow-temperature drop hammer performance of the steel plate is remarkably improved, and the yield is high.

Description

technical field [0001] The invention relates to a steel plate for X80 pipelines and a manufacturing method thereof, in particular to a steel plate for X80 pipelines with a thickness of more than 30 mm and a manufacturing method thereof, which has excellent ultra-low temperature drop weight performance. The application is also applicable to pipeline steels below X80 steel grade. Background technique [0002] At present, fossil energy still occupies a dominant position in the energy structure in the energy demanded by the world. The rapid growth of the world economy in recent years has greatly driven the rapid growth of fossil energy demand, which has also greatly promoted the development of long-distance transmission pipelines. Transmission efficiency, lower investment, and the development trend of steel for long-distance oil and gas pipelines is to develop towards high-strength or ultra-high steel grades. At present, the highest steel grade of pipeline steel used in countrie...

AI Technical Summary

Problems solved by technology

[0003] There are many domestic patent authorizations or patent applications for X80 pipeline steel, but there are few X80 patents involving thick specifications or even ultra-thick specifications and low-temperature drop-weight performance requirements, while ultra-low-temperature drop-weight performance requirements have basically not been reported.

[0004] For example, the patent No. CN101845596B mentions that the patent adopts the steel plate production method and is suitable for the production of X80 pipeline steel with a diameter of 20-35 mm or more. The S content of pipeline steel less than 20mmX80 is controlled at 0.005% and below. Too high S will seriously damage the toughness of pipeline steel, especially the drop hammer performance requirements of extra-thick steel plates; Ni≤0.20%, usually increasing the Ni content can improve the toughness of pipeline steel Especially the X80 pipeline steel with a thickness of more than 30mm is beneficial; 2) The key process window in the rolling process of this patent is very wide, which has little effect on the performance of steel grades below 23mm, but for pipeline steel with a thickness of 30mm and above, the performance It is difficult to guarantee, especially the drop weight performance. The applicant's practice has proved that it is difficult to meet the drop weight performance requirements with a thickness specification of 30mm or more by using this process and composition;

[0005] For example, the application patent No. CN103225047A mentioned that the application patent adopts the steel plate production method and is suitable for the production of X80 pipeline steel with a thickness not less than 26.5mm. The application patent has the following characteristics: 1) The patent requires that Mo is not less than 0.15%, In the case of ultra-thick specifications, the increase of Mo will bring about the sensitivity of grains and other structures, which is not good for the drop hammer performance, and also increases the cost of the alloy; Billet rolling has little effect on controlling the growth of austenite grains and refining ferrite grains; 2) In the subsequent rolling process, it is similar to that mentioned in the patent No. CN101845596B, and the process window is very wide , it is difficult to guarantee the performance of the drop hammer, which has also been reflected in my practice

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