Manufacturing method for low-cost, high-toughness and thin-specification 9Ni steel plate

Abstract

The invention discloses a manufacturing method for a low-cost, high-toughness and thin-specification 9Ni steel plate. Molten steel comprises 0.03%-0.06% of C, 0.1%-0.2% of Si, 0.5%-0.8% of Mn, 8.6%-9.1% of Ni, 0.02%-0.05% of Mo, 0.015%-0.035% of Als, smaller than or equal to 0.005% of S, smaller than or equal to 0.007% of P, smaller than or equal to 0.007% of N, and the balance Fe and impurities, wherein the impurities cannot be removed. A vacuum furnace with the vacuum degree smaller than or equal to 50 Pa is used for conducting smelting and alloying; the heating temperature ranges from 1,160 DEG C to 1,220 DEG C, the heat preservation time ranges from 90 min to 180 min, and the thickness of a blank ranges from 120 mm to 150 mm after cogging; two-stage controlled rolling is adopted, after rolling, the current temperature is kept for 10 s-15 s, then accelerated cooling is conducted to the temperature ranging from 440 DEG C to 550 DEG C with the cooling rate of 15-40 DEG C/s, and then air cooling is conducted to the room temperature; and the steel plate is heated to 575 DEG C-605 DEG C, and air cooling is conducted to the room temperature after tempering is conducted for 45 min-70 min. According to the manufacturing method, the characteristics of 9Ni steel materials and the thin-specification steel plate cooling characteristics are utilized, controlled rolling and controlled cooling are organically combined with a heat treatment technology, the material performance is improved, meanwhile, the technology process is shortened, the technology energy consumption is reduced, and the purpose of reducing the production cost of the high-toughness and thin-specification 9Ni steel plate is achieved.

Description

technical field [0001] The invention relates to a steel for ultra-low temperature and a manufacturing method thereof, in particular to a manufacturing method of a low-cost, high-strength, tough and thin-gauge 9Ni steel plate. Background technique [0002] As the proportion of natural gas in energy demand continues to increase, LNG transportation and storage technology develops rapidly, and 9Ni steel is widely used because of its excellent toughness at -196 °C ultra-low temperature environment. At present, my country has realized the large-scale industrial production of 9Ni steel. As a typical heat-treated steel, 9Ni steel is difficult to produce, especially because the heat treatment window is narrow and the process energy consumption is high, so the production cost is high (especially the thin-gauge 9Ni steel has high heat treatment cost per ton of steel). Therefore, how to implement effective organizational regulation in the previous process, so as to reduce the heat trea...

AI Technical Summary

Problems solved by technology

Another important issue worthy of attention is that in the above and other disclosed technologies, none of the 9Ni steel material characteristics has been used to propose an optimized process for thin specifications (8mm thickness and below), and there is a large room for process cost and consumption reduction.

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