Manufacturing method for rolled products for nuclear grade in-pile U-shaped embedded part locating pins

Abstract

The invention discloses a manufacturing method for rolled products for nuclear grade in-pile U-shaped embedded part locating pins, and aims to obtain the rolled products with uniform, fine and small-range grain structures and qualified tensile properties. The composition proportion is optimized; 3150-ton fast forging large deformation amount and single hammer reduction amount cogging is adopted, and four hammers are adopted in a 1800-ton diameter forging machine to achieve isothermal forging; the finished product rolling heating temperature is controlled at 1160 DEG C to 1180 DEG C, and secondary carbide and a gamma' strengthening phase generated by an alloy are re-dissolved, so that dynamic recrystallization of grains in the final rolling process is more uniform; small deformation mount quick rolling is adopted for the final-heating number rolling of finished products, it is guaranteed that all heating number rolling deformation is controlled to be uniform, the deformation amount is between 30% and 50%, the roller rotating speed is increased, and it is ensured that the final forging temperature is not lower than 950 DEG C. The manufacturing method has the beneficial effects that the carbon content is appropriately controlled, alloy elements such as aluminum, titanium and niobium are highly controlled, the hammer cogging and rolling processes are reasonably controlled, and thealloy rolled products with the uniform grain size structures and excellent performance are manufactured.

Description

technical field [0001] The invention belongs to the field of heat-resistant alloy manufacturing, and mainly relates to a method for manufacturing UNS N07750 alloy rolled material used for positioning pins of U-shaped inserts in nuclear reactors used in the temperature range of 350°C to 750°C. Background technique [0002] According to the nuclear power development plan, my country's nuclear power industry will usher in great development in the future. Before 2020, my country will build at least 35 million kilowatts of nuclear power units, with an average of 5 to 6 units per year. China's future planned units will all be third-generation nuclear power plants. . my country's third-generation nuclear power technology has experienced the initial complete import. By 2017, the first million-kilowatt-level pressurized water reactor nuclear power unit, Hualong No. 1, which was completely independently developed and produced, was officially delivered. It is ushering in the key to repl...

AI Technical Summary

Problems solved by technology

In the past, UNS N07750 alloy rolled products were billeted by forging hammers and formed by 500 horizontal rolling mills. Because the forging hammers were manually controlled, the forging speed was slow, the reduction amount of single hammer was small, and the final forging temperature was difficult to guarantee. Mixed crystal problem, billet quality is unstable; 500 horizontal rolling mill production, roll speed, final fire deformation, heating temperature and other process parameters are unreasonable, after 980 ° C for 2 hours ~ 4 hours + 845 ° C for 4 hours + 720 ° C for 20 hours Finally, the grain size grows unevenly, the range is large, and the room temperature mechanical properties of the body bar do not meet the requirements of not less than 965MPa, so the material is mostly dependent on imports, and the cost is high

This material is the core component of a nuclear reactor, and its organization and performance requirements are extremely strict, and its production and acceptance procedures are complicated. Its production and manufacturing process is a key technology in the field of nuclear-grade material manufacturing. At present, there is no public information at home and abroad.

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