Integrated seal head slab of pressure vessel for nuclear power and forge molding method thereof

Abstract

The invention discloses an integrated seal head slab of a pressure vessel for nuclear power. The slab comprises a slab main body which is of a circular plate-shaped structure; two manhole circular truncated cones and two tube hole circular truncated cones are arranged on one face of the slab main body while the other face of the slab main body is a large-cone-angle circular truncated cone. The ratio of the upper base diameter phi1 of the large-cone-angle circular truncated cone of the slab main body (1) to the outer diameter phi of the slab main body is as follows: phi1 / phi=1 / (1.80-1.90). The cone angle of the large-cone-angle circular truncated cone on the slab main body is 170-175 degrees. The forge molding method of the slab comprises the following steps: ingot heating; forging stock blanking; forging stock upsetting and drawing-out, wherein the upsetting and drawing-out ratio is 3.0-3.5; die forge molding; and thermal treatment of the slab. The every-time upsetting reduction rate in forging stock upsetting is 24-30%; the every-time drawing-out reduction rate in forging stock drawing-out is 24-30%. According to the invention, integral forge molding of the seal head slab can be realized, and a forge piece is uniform and compact in tissue and intact in metal streamline, so that forging of a seal head finished product is further facilitated and the mechanical property is improved.

Description

technical field [0001] The invention relates to a large structural part for nuclear power equipment, in particular to a head slab for forging an integrated head of a nuclear power pressure vessel, and also relates to a forging method for the head slab. Background technique [0002] As international energy becomes tense, all countries are vigorously developing new energy sources. Global nuclear power has entered a period of rapid development, and industrially developed countries and developing countries are actively committed to the development of nuclear power. my country's energy structure is also being adjusted to reduce the proportion of coal in the energy structure, and nuclear power is one of the main directions of energy development. [0003] At present, nuclear power technology is developing in the direction of large-scale development. The key components of nuclear power equipment need to use large-scale forgings. The slab diameter of the reactor pressure vessel and s...

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Problems solved by technology

[0004] However, 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.

It is difficult to manufacture such a large size, large deformation and complex curved surface integral slab with the existing forging method, and it is even more difficult to forge an ultra-large forging with an ideal metal structure and complete metal streamlines, and to forge a forging that meets the quality requirements. The head slab is the key to the production of qualified head products

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