Method for foundry production of ultra-supercritical main steam control valve for nuclear power unit

Abstract

The invention relates to a method of producing supercritical main stop governing valve by casting, and the method achieves the aim of replacing forging by casting by the improving of molten steel components control, pouring mode and heat treatment process, which greatly reduces the production cost. The pouring mode is the bottom pouring mode in a vertical state with a casting head on the upper part of the pouring position and an insulating sleeve is provided outside the casting head.The heat treatment process comprises techniques of quenching and double tempering. In order to obtaining casting parts with compact tissue, middle cavities of the casting parts are full of molten steel, axial cord shrinkage and shortage parts of the middle portion are removed by using a deep hole drilling, and the casting parts are then reprocessed for satisfying the requirements of the size of the middle cavities. Mechanical properties of the casting products comprises a yield strength delt0.2>=520MPa, a tensile strength deltb>=680-850MPa, a tensile stretch delt5>=15%, a reduction in cross section psi >=40% and an impact energy AkU >= 30J.

Description

technical field [0001] The invention relates to a method for manufacturing an ultra-supercritical main steam regulating valve for a nuclear power unit, in particular to a method for casting and producing an ultra-supercritical main steam regulating valve for a nuclear power unit. Background technique [0002] In the prior art, most ultra-supercritical regulating valves are mainly forgings, which have a long procurement cycle and high manufacturing costs. With the development of steam turbine technology and the continuous construction of high-power ultra-supercritical thermal power units, the market demand for this valve body will increase significantly and the market prospect is extremely broad. [0003] Since 2003, my country has started the research and development of ultra-supercritical units, but with the improvement of unit parameters, the requirements for materials have also been further improved. The operating temperature of ultra-supercritical steam turbine is highe...

AI Technical Summary

Problems solved by technology

The Cr content is between 9.1 and 10.00. Due to the large number of control elements, the smelting time is long

Increased the difficulty of smelting

[0006] 2. In terms of casting, due to large thermal joints and poor fluidity of molten steel, it brings certain difficulties to the design of casting risers, runners, subsidies, and scaling

[0007] 3. The performance requirements of this material are extremely high. In order to ensure the performance, heat treatment is a difficulty. There is no domestic experience for reference. A large number of experiments must be done to master the core technology of heat treatment of this material

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