High-strength and high-toughness thick-plate structural steel for low temperature and heat treatment method thereof

Abstract

The invention relates to high-strength and high-toughness thick-plate structural steel for the low temperature and a heat treatment method thereof. The steel is prepared from 0.03%-0.08% of C, 0.8%-1.9% of Cr, 0.01%-1.0% of Mn, 3.5%-7% of Ni, 0.2%-0.5% of Mo, 0.15%-0.2% of V, 0.01%-0.05% of Nb, 1.2%-3.8% of Cu, 0-0.5% of Al, less than or equal to 0.015% of P, less than or equal to 0.010% of S andthe balance Fe and inevitable impurities. Compared with the prior art, steel plates prepared from the steel can be used at the temperature ranging from subzero 20 DEG C to subzero 120 DEG C and at thelower temperature being subzero 196 DEG C and can keep the relatively high strength and certain toughness, and the technical problems that existing high-strength and high-toughness hardened and tempered steel cannot meet requirements of equipment for resource and energy development, transportation and the like in polar regions are mainly solved.

Description

technical field [0001] The invention relates to the field of thick-plate low-temperature structural steel, in particular to a high-strength and high-toughness thick-plate structural steel for low temperature and a heat treatment method thereof. Background technique [0002] The regulation of microstructure and nanostructure based on precipitation and phase transition theory has always been the main way to strengthen and toughen advanced steel materials, and it is also the theoretical basis for developing a new generation of high-strength and high-toughness steels. A very ideal microstructure and excellent mechanical properties can be regulated by skillfully utilizing the coupling effect of "force" and "heat" in the thermal processing process. For example, repeated low-temperature deformation combined with tempering can significantly refine the grains of conventional low-alloy steel, thereby improving its low-temperature toughness; rapid heating, instantaneous heat preservati...

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Problems solved by technology

[0003] However, multi-step heat treatment is a general concept, although its purpose is clear, that is, ① realize fine grain strengthening and toughening of cyclic annealing, ② reverse transformation austenite toughening of critical tempering in two-phase region, and ③ conventional tempering of nano Precipitation strengthening of the second phase, but it lacks necessary and specific selection criteria for parameters such as heat treatment temperature, time and steps

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