Establishment And Prediction Of A Model For The Oblique Rolling Perforation Process Of Incoloy825 Seamless Pipe

Seamless steel pipes are widely used in major fields such as petrochemicals,automobiles,ships,aerospace,weapons and equipment,and are of great significance for national economic construction and national defense development.With the rapid development of technology,high-end technological equipment has put forward higher requirements for the production quality of seamless steel pipes.High dimensional accuracy,high surface quality,and high strength seamless steel pipes have become an inevitable trend in the development of steel enterprises.Due to the complex deformation process and large degree of deformation during cross rolling perforation,the capillary is prone to damage and defects,making cross rolling perforation a key technical problem that restricts the production of seamless steel pipes.The paper systematically studied the mechanism of capillary damage and failure during the cross rolling piercing process,and predicted the damage defects of the capillary,which has certain practical guiding significance.This article takes Incoloy825 nickel based alloy seamless pipe as the research object,adopts three-dimensional modeling and finite element simulation methods,combined with room temperature tensile experiments and high temperature tensile experiments,to explore the mechanism of damage defects during the cross rolling perforation process,predict the location of damage occurrence,and verify the accuracy of prediction through experiments.The main content and results are as follows:(1)By conducting room temperature stretching,room temperature notch specimen stretching,and high temperature hot stretching experiments on Incoloy825 nickel based alloy,the microscopic fracture morphology was observed,and the plastic deformation patterns of Incoloy825 nickel based alloy under different deformation temperatures,strain rates,and stress triaxiality were obtained.A material model of Incoloy825 nickel based alloy was established.(2)Through the research on the theory of cross rolling piercing,the motion state and mechanical properties of each stage in the process of cross rolling piercing are analyzed,the thermodynamic coupling model of cross rolling piercing process and the geometric modeling of roll,plug,guide plate,push block,tube blank,etc.are established,the boundary conditions are set and the adaptive grid is divided,and the parameters required for simulation are determined according to the cross rolling piercing data provided by a factory.(3)Through theoretical research on Johnson Cook model and failure Johnson Cook model,the change of area reduction rate of notch specimen and high-temperature specimen of Incoloy825 nickel base alloy after tension was analyzed.The change rule between stress triaxiality and failure strain,strain rate and failure strain,temperature and failure strain was mastered,and the required damage parameters and damage model constitutive equation were obtained by fitting.(4)Through finite element simulation of the four stages in the cross rolling perforation process,the temperature field,equivalent stress,equivalent plastic strain,stress triaxiality changes under different rolling temperatures and speeds,as well as the influence of rolling parameters on damage generation,were mastered.The location of damage defects was accurately predicted and verified in actual production.