Near-net forming forging method of integrated bottom head of nuclear reactor pressure vessel

Abstract

The invention discloses a near-net forming forging method of an integrated bottom head of a nuclear reactor pressure vessel. The method includes: determining characteristic dimension parameters of the integrated bottom head, manufacturing a special wedged hammerhead and a lower female die for prefabrication of a blank, and a male die and three upper hammerheads for rotary forging according to the characteristic dimension parameters, upsetting the prefabricated blank by a hydraulic machine, mounting and centering the lower female die and the special wedged hammerhead, extruding the prefabricated blank with the special wedged hammerhead and the lower female die to obtain a recess, stopping rotary forging when hold-down height deltaH is 1100 mm, turning the blank by 180 degrees, subjecting the blank to rotary forging with the male die and the three upper hammerheads to obtain certain wall thickness, and detecting the size of the blank to obtain the finished integrated bottom head product. The method has the advantages that the integrated overall bottom head can be forged by the method, the shape of the forging is close to that of a part, forging efficiency is improved, production cost is lowered and mechanical properties of the forging are guaranteed.

Description

technical field [0001] The invention relates to a near-net shape forging method for an integrated bottom head of a nuclear reactor pressure vessel. Background technique [0002] At present, the bottom head parts of a million-kilowatt nuclear reactor are made of two forgings, the transition section and the lower head, respectively, and then assembled and welded into an integrated bottom head part. Due to the large size of the split forgings of the transition section and the lower head, the welding workload is very large. During the welding process, the transition section and the lower head need to be repeatedly preheated and post-weld heat treated, which greatly prolongs the production cycle and increases the production cost. At the same time, repeated heating also brings potential risks to the mechanical properties of forgings. [0003] Due to the large depth of the large-scale integrated bottom head forging, the distance from the opening end of the bottom head to the botto...

AI Technical Summary

Problems solved by technology

[0003] Due to the large depth of the large-scale integrated bottom head forging, the distance from the opening end of the bottom head to the bottom is greater than the maximum outer diameter of the bottom head. In this way, the conventional slab stamping and stretching bottom head process scheme can no longer meet the requirements. To this end, a large number of numerical simulations and physical simulation tests have been carried out, and a controlled forming forging process plan has been developed to control the metal flow state, ensure the fullness of the forging and minimize the margin, and has been successfully put into production

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