Method for adopting powder metallurgy hot isostatic pressing near-net-shape forming technology for preparing motor protecting ring

Abstract

The invention provides a method for adopting a powder metallurgy hot isostatic pressing near-net-shape forming technology for preparing a motor protecting ring and belongs to the field of metal materials. The protecting ring is made of a protecting ring steel material with the nitrogen content of 0.4-1.0%, the process of combining a pressurizing induction melting of mother alloy and nitrogen atomization is adopted for preparing powder with the average granularity of 5 micrometers-100 micrometers, the powder is placed into a cylindrical or a circular-ring-shaped bag sleeve, then vacuumizing and seal welding are carried out, then the powder is placed in a hot isostatic pressing furnace for pressurization and heat preservation, compacting is carried out on the powder to obtain a protecting ring blank, the bag sleeve is turned off through a machining method, cold swelling formation and annealing stress relief are carried out on the blank, the processing temperature ranges from 330 DEG C to 350 DEG C, the speed of temperature rising is smaller than 40 DEG C per hour, the speed of temperature falling is smaller than 30 DEG C per hour, and time for heat preservation ranges from 10 minutes-12 minutes. According to the method, the texture performance is uniform, the crystal particles are small, the overall performance of products is high, the use reliability of the protecting ring and a whole machine can be improved greatly, surface cracks of the protecting ring in the manufacturing process can be effectively avoided, the protecting ring is treated in the mode of being free from solid solutions, the rate of finished products is effectively increased, and the manufacturing cost can be effectively lowered.

Description

technical field [0001] The invention belongs to the field of metal materials, and relates to a method for preparing a motor retaining ring by using powder metallurgy hot isostatic pressing near-net forming technology. Background technique [0002] The retaining ring is a large forging steel ring that is pressed and assembled at both ends of the generator rotor, and is one of the large key parts of thermal power generation equipment. The force of the retaining ring is complicated during high-speed rotation. It not only has to bear huge centrifugal force, but also bears the assembly stress during shrink fitting, the additional stress caused by uneven load, the alternating stress from the rotor and the structural requirements. concentrated stress. Therefore, in order to ensure the long-term safe operation of the unit, the retaining ring is required to have sufficient strength, good toughness, uniform mechanical properties and minimum residual stress. The retaining ring works ...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to solve the technical problems existing in the multi-fire forging process that the process is complex, the surface of the retaining ring is prone to cracks, and the internal structure and performance are not uniform

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