The Research Of Die Forging Grain Refinement Model And Optimization Process Of Heavy Forgings Of Valve

The manufacturing of heavy forgings plays a pivotal role in the national economic construction,national defense equipment development and modern advanced science and technology research.It is also the foundation of national large scale equipment.Heavy forgings are widely used in petrochemical equipment.As the key part of petrochemical equipment,the comprehensive performance of heavy forgings of the oil pipeline valve needs to improve urgently.Currently,the computer numerical simulation is applied to simulate the forming process of heavy forgings to achieve the forecast of manufacturing and product quality of forging products and to save cost and reduce time taken for development at the same time.This article is based on the research object,35 CrMo steel and the problems happened in the actual production such as coarse and asymmetric grain and mechanical properties of large forgings.(1)According to the part drawing of “4-1/16? oil pipeline valve” provided by the manufacturer of actual production,the combination of forging drawing of valve and the initial blank size can optimize actual parts of mold and the 3D modeling of die is improved.(2)By investigating the re-crystallization model of 35 CrMo steel,the grain refinement model proper for the die forging production is required,and the Fortran language is used to complete the writing of user subroutines for grain refinement model.(3)The grain refinement model is put into the 3D finite element software to simulate the process of forging and the different factors on the average grain size of product are analyzed,and the effects of process parameters on the average grain size is investigated.(4)Based on the simulation results of orthogonal test,the effects of process parameters such as the proper selected parameters of bridge height and width,the interval times of forging,the forging energy level are studied and their impacts on the average size of grains are analyzed.The results are used to determine which process parameter is most optimal and further improve it.(5)By analyzing the simulation result of optimum technology project and studying the micro-structure conditions of heavy forgings such as the dynamic re-crystallization volume fraction,the sub-dynamic re-crystallization volume fraction and the distribution of average grain size,and the mechanism of grain refinement model of die forging is investigated in the process.(6)The results of physical experiment and simulation are being compared and analyzed.These include analyzing the mechanical properties and the refinement efficiency of internal grain,the strength and hardness of valve and so on.The following conclusions are drawn from the results of comparison between numerical simulation and physical experiment.The use of finite element numerical stimulation technology can stimulate the die forging process accurately,which further optimizes the parameters of forging process and mold size.The grain refinement is also forecasted in the forging process.As a result,production cost and time taken for development are effectively reduced and this builds up a stronger foundation to reduce defects and to improve the quality of valve which is advantageous to the green and low-carbon development of industrial production of heavy forgings.