Integrated head of pressure vessel for nuclear power, its head slab and forging method

Abstract

A monoblock forging of a nuclear power steam generator housing comprises a monoblock forging body, and a forging manhole seat and a forging pipe hole seat provided on the monoblock forging body, the monoblock forging body having a spherical cap structure, a forging manhole and a forging pipe hole being provided on the forging manhole seat and on the forging pipe hole seat respectively, the forging manhole seat and the forging pipe hole seat being integrated, by forging, with the monoblock forging, the hole centerline of the forging manhole and the hole centerline of the forging pipe hole intersecting at the center of the sphere where the monoblock forging body is located. A method for molding the monoblock forging of the nuclear power steam generator housing by forging comprises the following steps: heating a steel ingot; forging stock blanking; forging stock upsetting and stretching; die forging molding; slab heat treatment; slab roughing; forging molding; forging punching; forging heat treatment; forging machining; performance heat treatment; and finished product processing. The molding method by forging not only realizes the integral molding of the steam generator forging, but also realizes a uniform and dense forging structure and a complete metal flow line, and enables the forging fiber structure to be more consistent with the appearance.

Description

technical field [0001] The invention relates to a large structural part for nuclear power equipment, in particular to a head for pressure vessels such as nuclear power steam generators, a head slab and a forging method thereof. Background technique [0002] Due to the advantages of less resource consumption, less environmental impact and strong supply capacity, nuclear power has become one of the world's three major power supply pillars alongside thermal power and hydropower. Nuclear power will not emit a huge amount of pollutants into the atmosphere like fossil fuel power generation, and nuclear power generation will not cause air pollution; the energy density of nuclear fuel used in nuclear power generation is several million times higher than that of fossil fuels, so the nuclear power plants used The fuel is small in size and easy to transport and store. Therefore, nuclear power is a clean and safe energy source, and the environmental impact of nuclear power is small. ...

AI Technical Summary

Problems solved by technology

Therefore, the head of the steam generator is provided with two pipe hole seats and two manhole seats on the main body of the hemispherical crown; the expanded diameter of the slab can reach 7-8 meters, and the weight of a single finished part is more than tens of tons , which is a super-large plate-shaped component, is very difficult to forge, and it is even more difficult to forge a pipe hole seat and a manhole seat that meet the size and position requirements on such a large-sized spherical crown at one time.

Therefore, the existing head is manufactured by splicing the head body, the manhole seat and the pipe hole seat by welding. Although with the development of material science, the performance of the welding material has been greatly improved, and the new welding process has also been improved. However, the welded structure between the main body of the head and the manhole seat and the nozzle hole seat cannot always form a complete metal flow line. Because the nuclear power steam generator has been in the harsh operating environment of high temperature and high pressure for a long time, and withstands the The sudden change of pressure formed by variable load and pipeline eddy current can easily cause uneven stress distribution and stress concentration, which is prone to fatigue, creep and damage

Moreover, in the method of separately welding and manufacturing the spherical crown and the nozzle, the welding process is very complicated, the welding cycle is long, and the quality stability of the complex stress area is poor, which directly leads to low yield and a substantial increase in manufacturing costs.

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