Manufacture a martensitic stainless steel pump casing product for containment spray pumps used in nuclear power plants

Abstract

The invention relates to a martensitic stainless steel pump case product for manufacturing a spray pump of a containment for a nuclear power plant. High purity molten steel with low gas content and uniform components is obtained by intermediate frequency furnace and VOD duplexing smelting; process parameters are obtained by system design of industrial analysis, chromite sands are used in a pump case runner, and the outer layer of the chromite sands is cast by furan resin sands to ensure that the runner is smooth and level; the accuracy of a core assembly and a lower core is ensured by using a snap-gauge, so that the dimensional tolerance of the runner satisfies the requirement; thermal treatment process parameters are adjusted through a process test, in-furnace temperature, temperature raising rate, insulating temperature, quenching temperature and quenching transfer time are controlled, and the problems of low impact performance and high hardness are solved through tempering twice. The problem that previous cast product is more in porosity defect, severe in surface sand burning, poor in dimensional precision of the runner and relatively poor in mechanical property is solved, and the corrosion-resistant martensitic stainless steel pump case cast which is high in dimensional precision, few in technical defect, compact in internal tissue and free of sand burning in the cavity of the runner is obtained.

Description

technical field [0001] The invention relates to the manufacturing field of a centrifugal pump, in particular to manufacturing a martensitic stainless steel pump shell product of a spray pump used in a nuclear power plant. Background technique [0002] Containment sprinkler pump is one of the important safety equipment of nuclear power plant. It is an integral part of the safety injection system and an important nuclear secondary pump. Safe injection in case of rupture. The pump casing is one of the main components of the containment spray pump, which plays the role of support and fixation, and is connected with the bracket for installing the bearing. The function is to seal the impeller in a certain space, so that the liquid can be sucked in by the high-speed rotating impeller and pressed out under high pressure. [0003] At present, the pump casing material of the containment spray pump is Z5CND13-04 in the French RCC-M standard. This material belongs to martensitic stain...

AI Technical Summary

Problems solved by technology

[0004] The object of the present invention is to provide a martensitic stainless steel pump casing product for containment spray pumps used in nuclear power plants. The manufacturing process of the product includes the following steps: according to the pump casing material, the smelting process of intermediate frequency furnace + VOD dual method is adopted Control the N, H, O gas content of the casting; use the process analysis system CAE / InterCAST, computer three-dimensional design to simulate casting feeding and dimensional shrinkage under different conditions of pouring temperature, riser size, and gating system to obtain the best process parameters; Chromite sand is used in the flow channel of the pump casing, and the outer layer of the chromite sand is cast with furan resin sand to ensure smoothness and flatness in the flow channel; in order to ensure that the assembly core and the lower core will not be deviated due to human operation, the clamping plate is designed and manufactured method to ensure the accuracy of core assembly and lower core, so that the size tolerance of the flow channel can meet the requirements; continuously adjust the heat treatment process parameters through technological tests, in the furnace temperature, heating rate, holding temperature, quenching temperature and quenching transfer time, quenching The medium is strictly controlled to solve the problem of low impact performance and high hardness