Easy-to-weld container plate with thickness ranging from 40 millimeters to 60 millimeters and excellent center low-temperature toughness, and making method thereof

Abstract

The invention relates to an easy-to-weld container plate with the thickness ranging from 40 millimeters to 60 millimeters and the excellent center low-temperature toughness, and a making method thereof. The steel plate comprises the chemical ingredients, by mass, 0.04% to 0.09% of C, equal to or smaller than 0.40% of Si, 1.00% to 1.60% of Mn, equal to or smaller than 0.008% of P, equal to or smaller than 0.002% of S, 0.12% to 0.30% of Mo, equal to or smaller than 0.10% of the sum of Nb, V and Ti, 0.20% to 0.60% of Ni, 25 ppm to 55 ppm of N, equal to or smaller than 2ppm of H, the balance Fe and unavoidable impurity elements. Meanwhile, the steel plate meets the conditions that Pcm is equal to or smaller than 0.20%, w(Nb+V)/w(Ti) ranges from 10 to 30, the yield strength of the steel plate is larger than or equal to 490MPa, the tensile strength Rm of the steel plate is larger than or equal to 620MPa, the elongation A is larger than or equal to 21%, the yield ratio is equal to or smallerthan 0.88, the side knock power minus 50 DEG C KV2 of the position of one fourth of the thickness of the plate is larger than or equal to 220 J, and the side knock power minus 50 DEG C KV2 of the position of one second of the thickness of the plate is larger than or equal to 100 J. The method comprises the following working steps of molten iron pretreatment, converter smelting, ladle furnace refining, vacuum treatment, continuous casting, casting blank cover cooling, casting blank heating, controlled rolling, controlled cooling, stack retarded cooling, quenching, tempering, flaw detection andperformance examination. The easy-to-weld container plate with the thickness ranging from 40 millimeters to 60 millimeters and the excellent center low-temperature toughness not only has the excellenttoughness matching, but also has the excellent center low-temperature impact toughness, and thereby meeting the requirements on steel for a large spherical tank.

Description

technical field [0001] The invention relates to a container steel plate with a thickness of 40-60mm and excellent low-temperature toughness at an easy-to-weld core and a manufacturing method thereof, belonging to the technical field of metal materials. Background technique [0002] With the rapid development of the national economy, the demand for petrochemical products is increasing, and there are more and more storage tanks for various petroleum and chemical products. Spherical storage tanks are becoming more and more popular because of their unique advantages. The volume of the spherical tank is constantly developing toward larger size. In order to ensure the large-scale development of the spherical tank, it is necessary to develop the low-temperature impact toughness of the steel used for the spherical tank, especially the low-temperature impact toughness and weldability of the core. [0003] my country's strategic oil reserve capacity will continue to increase, and the ...

AI Technical Summary

Problems solved by technology

[0007] To sum up, although the existing steel for large spherical tanks has good strength, toughness and welding performance, the service temperature is high and the low temperature impact toughness of the core of the steel plate cannot be guaranteed, which cannot meet the requirements of the existing steel for extra large spherical tanks. skills requirement

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