A forging method for controlling the grain size of a super-large cross-section axial austenitic pipe

Abstract

The invention relates to the technical field of metal forging, and discloses a forging method for controlling the grain size of a shaft-like austenitic pipe with a super large cross-section. 1. Secondary upsetting, secondary elongation, number printing and material distribution, preliminary elongation and elongation completion eight processes. The method first breaks columnar crystals, improves macro segregation, breaks as-cast structure, welds internal pores through high temperature and large deformation forging technology, obtains reasonable fiber direction distribution, improves material density, refines crystal grains and uniform structure. At the same time, control the deformation rate of the single-fired billet, balance the deformation and recrystallization process, and avoid local forging in the single-fired state to obtain a more uniform grain structure. By rationally setting the forging forming process, no other additional tooling is required, and the product cost is effectively reduced. Through the above method, the finished main pipe with accurate size, qualified flaw detection and excellent grain size can be obtained.

Description

technical field [0001] The invention relates to the technical field of metal forging, in particular to a forging method for controlling the grain size of a super-large cross-section axial austenite pipe. Background technique [0002] The CAP1400 nuclear power plant is one of the landmark projects of my country's construction of an innovative country. It is developed by my country Nuclear Engineering Co., Ltd. on the basis of digesting and absorbing the third-generation nuclear power AP1000 technology introduced by my country. Passive large-scale advanced pressurized water reactor nuclear power technology brand. With the continuous upgrading of my country's nuclear power technology, higher requirements have been placed on nuclear power equipment. For example, the main pipeline, as one of the seven key equipment of the nuclear island, has stricter requirements on mechanical properties, forging quality and grain grade. [0003] CAP1400 main pipeline adopts integral forging pipe...

AI Technical Summary

Problems solved by technology

With the increase of steel ingots required for CAP1400 main pipe forgings, it not only increases the difficulty of forging and forming, but also increases the smelting defects of the steel ingots themselves, which increases the final flaw detection risk of forgings and makes it difficult to meet the final grain size requirements of forgings

[0005] Therefore, the control of grain size of forgings is still the key technical point of main pipeline forgings, and there is no domestic main pipeline forgings that can meet the requirements of grain size above 2.7

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