Deformation And Process Optimization Of Nuclear Power Main Pipeline In Solid Solution Process

The AP1000 nuclear power main pipeline is one of the seven key equipment of the nuclear island and is called the "aorta" of the nuclear power plant.The solution process is particularly important as the last thermal processing process of the main pipeline.The quenching deformation of the main pipeline after solution solution will affect the installation and service life of the equipment.A reasonable solution process can not only improve the performance of the main pipeline,but also accurately control it.The structure and size of the main pipeline.Studying the solid solution process of the main pipeline is beneficial to reveal the quenching deformation mechanism of the main pipeline,improve its quenching deformation,and provide theoretical support for optimizing the solution process.Due to the large size and high cost of the main pipeline,it is not suitable to use physical experiments.Therefore,this paper uses the finite element simulation method to study the solid solution process of the main pipeline to provide a reference for optimizing the actual process.This paper uses a combination of experiment and numerical simulation to study the deformation law of the main pipeline during the solid solution process.First,the true stress-strain curve of the main pipe material 316 LN is obtained through thermal simulation experiments,and the constitutive equation of the material is established from this,and it is applied to the solid solution process simulation of the main pipe.Then,based on the ABAQUS finite element software,the thermo-mechanical coupling simulation calculation of the solid solution process of the main pipeline is carried out.By studying the change law of the temperature field of the main pipeline in the solid solution process,it is found that the maximum temperature difference between the different wall thickness parts of the main pipeline reaches 167.8 °C during the heating and holding process.With the increase of the holding time,the temperature field gradually becomes uniform;during the quenching process,The maximum temperature difference between different wall thicknesses reaches 531.6 °C.The sequential coupling method was used to analyze the influence of the uneven temperature field on the deformation of the main pipeline.The study found that the shape change of the main pipeline mainly occurred in the quenching stage,and the necking deformation of each nozzle occurred in the early stage of quenching.As the quenching continues,the entire pipeline occurs.Uneven deformation.After quenching,the two straight sections of the main pipeline are flared and deformed.Studies have shown that the Keep warm time affects the quenching residual stress and deformation of the main pipe.While ensuring the solid solution temperature,the shorter the heat preservation time,the smaller the quenching deformation of the main pipe;As the transfer time of the main pipeline increases,the quenching deformation gradually increases;the deformation of the nozzle decreases with the increase of the water inlet speed,and it is more significant at the water inlet speed of 15-30 mm/s;Quenching With the increase of the medium temperature,the quenching residual stress of the main pipeline gradually decreases.When the medium temperature reaches 55.0 °C,the effect of reducing the quenching residual stress gradually weakens.By changing the size of the main pipe,the quenching deformation of the main pipe was improved,and it was found that extending the size of the straight section of the main pipe would increase the range of the nozzle deformation zone.