Composite manufacturing method for seawater pump impeller nut

Abstract

The invention relates to the technical field of seawater pumps, and provides a compound manufacturing method for seawater pump impeller nuts, which includes the following steps: casting a base material to be surfacing with cast steel, and adopting a method of strip electroslag surfacing after the base material is cleaned A layer of 316L stainless steel is deposited on the outer surface of the base metal; martensitic stainless steel is deposited on the inner cavity wall of the base metal by electrode arc welding; the outer surface of the nut is processed and milled; threads are tapped on the inner cavity of the base metal. Through the above-mentioned process, the present invention can "put" a corrosion-resistant alloy shell on the outer surface of cast steel, and the inner cavity is made of martensitic stainless steel. The thread layer has excellent wear resistance, and the finished product has the advantages of wear resistance and corrosion resistance. , The service life is greatly improved compared with the traditional single material manufacturing impeller nut.

Description

technical field [0001] The invention relates to the technical field of seawater pumps, in particular to a compound manufacturing method for seawater pump impeller nuts. Background technique [0002] The seawater pump is a machine that transfers the mechanical energy of the motor to seawater. It is widely used in coastal firefighting, seawater desalination, tidal power generation and other occasions. The flow-passing parts of the seawater pump mainly include: suction chamber, pressure discharge chamber, impeller, impeller nut and pump casing. As a component that restricts the axial translation of the impeller, the impeller nut also bears the erosion of seawater flow in the working state, and is extremely vulnerable to corrosion and failure. There are mainly two types of methods in the existing technology to solve the problem of easy corrosion of impeller nuts: one is to put a polymer anti-rust shell on the outer surface of the nut. The main disadvantage of this method is tha...

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Problems solved by technology

As a component that restricts the axial translation of the impeller, the impeller nut also bears the erosion of seawater flow in the working state, and is extremely susceptible to corrosion failure

There are mainly two types of methods in the existing technology to solve the problem of easy corrosion of impeller nuts: one is to put a polymer anti-rust shell on the outer surface of the nut. The main disadvantage of this method is that the shell and the internal metal do not form an atomic connection. There are cracks in the outer shell, but this structure helps seawater to stay between the metal and the outer shell, and accelerates the corrosion of the metal; another process is to use high-alloy stainless steel precision casting impeller nuts as a whole, and its main disadvantage is that it is usually used for casting nuts The hardness of the stainless steel material is not high, generally less than 20HRC, and the impeller nut made of a single material is prone to thread wear or even stuck faults during use

Because of the low dilution rate of strip electroslag surfacing (less than 15%), the deposition efficiency is high

Ordinary martensitic welding core adopts the method of increasing the solid solution carbon content to increase the hardness of the surfacing layer, which brings problems of corrosion resistance and poor toughness, and cannot be directly applied to the manufacture of seawater pump impeller nuts

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