Electric smelting forming method for nuclear power station pressure vessel shell

Abstract

The invention provides an electric smelting forming method for a nuclear power station pressure vessel shell. The method is efficient and low in cost and has the good mechanical property. The method comprises the steps that an electric smelting head and a base material are connected to two electrodes of a power source, and in the forming process, a metal raw material wire is conveyed to the surface of the base material through a conveying mechanism and the electric smelting head; under accumulation protection of a granular auxiliary material, an electric arc is generated between the raw material wire and the base material, and a molten slag pool is formed by smelting part of the accumulated laid auxiliary material; a current flows through the raw material wire and the molten auxiliary material slag pool to form resistant heat and electric slag heat; under the effect of three composite high-energy heat sources of the electric arc heat, the resistance heat and the electric slag heat, the raw material wire is smelted, and a local smelting pool is formed on the surface of the base material; the raw material wire and the auxiliary material are continuously conveyed; according to hierarchy slicing data of a forming component, a computer is adopted to control relative moving of the electric smelting head and the base material; and the aim that the smelting pool is rapidly cooled on the base material and solidified and stacked layer by layer, and finally the nuclear power station pressure vessel shell is formed is achieved.

Description

technical field [0001] The invention relates to an electric fusion forming method for a nuclear power plant pressure vessel cylinder body. Background technique [0002] As the heart equipment in the nuclear island of a nuclear power plant, the reactor pressure vessel is mainly used to hold the reactor core, keep the high temperature and high pressure coolant in a sealed shell, and at the same time play a role of radiation shielding. The strong neutron irradiation makes the material performance continuously been exacerbated. Therefore, the harsh working environment, the ever-increasing extreme requirements for nuclear power safety, and the container itself as a non-replaceable part of the nuclear island will become larger and larger as the power generation increases. The requirements for nuclear power pressure vessel materials are very strict and are becoming more and more higher. [0003] At present, the pressure vessel material is Mn-Mo-Ni low-alloy high-strength steel (A...

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Problems solved by technology

[0004] Although this method is widely used in industrial production, it is still very difficult to manufacture special material parts due to the actual manufacturing level of forging enterprises in my country. Taking a typical third-generation nuclear power AP1000 pressure vessel as an example, the production of integrated roof and head materials Scrapping abounds, and the success rate is extremely low. And because of the technical limitations of steel ingot smelting and forging, the container cylinder and special parts are forged in sections and then assembled and welded together. Obviously, the increase in welds splits the mechanical fibers. Continuity, which greatly affects the mechanical properties of the material. And the forming efficiency is low, the manufacturing cycle is long, and the cost is increased.

[0005] Moreover, due to the thick cross-sectional size of the pressure vessel, during heat treatment, the core and the surface undergo different heat treatment speeds during the heating and cooling process, which is prone to stress cracking, and the macroscopic material phase structure is not uniform, so it is difficult to obtain good full-section properties. .In addition, judging from the final grain measurement results of this process, the pressure vessel material is generally only about 5-7 grades. For the purpose of improving the mechanical properties, especially the comprehensive performance of strength and toughness, through refining grains in the current research and development and production , the process has a large bottleneck

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