Steel for nuclear reactor pressure vessel and preparation method of steel

Abstract

The invention provides steel for a nuclear reactor pressure vessel. The steel comprises, by mass, 0.12-0.20% of C, 0.05-0.15% of Si, 0.25-0.40% of Mn, 0-0.006% of P, 0-0.004% of S, 3.0-3.9% of Ni, 1.5-2.9% of Cr, 0.45-0.70% of Mo, 0.01-0.02% of Al, and the balance Fe. According to the steel for the nuclear reactor pressure vessel, on the basis of the limited components, the hardenability is improved remarkably, coordination and cooperation between all the components are guaranteed, and the effect that the function of each component is brought into full play when each component exists alone is guaranteed; and the size, distribution state, shape and content of precipitated carbide in the phase change process are affected by coordination and cooperation of all the components, and accordingly the structure performance is affected.

Description

technical field [0001] The invention belongs to the technical field of steel for pressure vessels, and in particular relates to a steel for nuclear reactor pressure vessels and a preparation method thereof. Background technique [0002] With the rapid economic development of various countries and the expansion of the limitations of traditional energy sources, nuclear energy, as the most promising energy source for human beings, has been favored by all countries, and all countries have increased the development and utilization of nuclear energy. [0003] The nuclear reactor pressure vessel is the main support structure of the nuclear reactor core. It transmits the heat released by the core through the cooling circulating water to drive the generator set to generate electricity. It is the second safety barrier for the core. The steel used for nuclear reactor pressure vessels is mostly Mn-Ni-Mo low-alloy steel with a carbon content of 0.2%, which belongs to the third generation...

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Problems solved by technology

However, the existing nuclear reactor pressure vessel material steel has poor hardenability and shallow hardening depth on both sides. During the quenching heat treatment process, especially when the thickness of the material is greater than 500mm, it is difficult to completely transform into a martensitic structure; when the material When the martensite structure cannot be completely obtained, the quenching and tempering treatment cannot form a uniform structure, which will lead to uneven mechanical properties, especially at the 1 / 2 thickness of the material, where the performance is the worst, and the low temperature impact toughness is poor

[0005] In order to make up for the defects in performance, the thickness of the material needs to be increased, but the increase in the thickness of the material will lead to an increase in the weight of the raw material of the nuclear reactor pressure vessel, such as the construction of a nuclear power plant greater than 1350MW, using the existing Mn-Ni-Mo low-alloy high-strength steel material When preparing nuclear reactor pressure vessels, the raw material steel ingot weighs 500t, and the forging weighs 350t. Since the double-sided hardening depth of this type of steel is less than 500mm, it is difficult to produce such a large steel ingot at the current production level, and it is impossible to ensure large Uniformity of structure and properties at the cross-section

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