Finite Element Simulation And Experimental Study On Large-section Forgings Of High-quality Mold Steel

In recent years,with the development of science and technology,the forging technology has also been rapidly upgraded in our country.However,the forging process design of large steel ingots in production applications.Most domestic factories still use the experience accumulated in traditional production and a large number of tests to solve the problem.This not only causes waste of resources,complicated process,and low forging efficiency,which increases production costs,but also can not ensure the quality of forgings.Therefore,there are problems with the forging process for large forgings.This paper develops an isotropic forging technique for studying large-section forgings using finite element simulation.Relying on the project of "Key technology of hot processing and organization control of high-quality die steel”in "High-performance tool steel and application" in "13th Five-Year" National Key R&D Program.In this paper,3Cr2MnNiMo plastic mold steel is used as the research object of simulated forging.The chemical composition and as-cast microstructure of 3Cr2MnNiMo plastic mold steel were analyzed.The effect of forging process on the as-cast microstructure and properties of steel ingots was studied.3Cr2MnNiMo plastic mold steel belongs to medium carbon alloy steel.The tissue at the edge of the steel ingot is denser than the tissue at the center.The distribution of carbides is more uniform and the large columnar grains become fine equiaxed grains after the steel ingot is forged.Defects such as voids and microcracks are eliminated during the forging process.The plasticity and toughness of the steel ingot are increased,and the mechanical properties are improved.The homogeneity and isotropy are two important performance indicators of die steel.Forging ratio and forging deformation rate are a method to measure the degree of metal deformation during forging.The measurement accuracy of these two methods in actual forging is low,and there is a deficiency.Based on the finite element simulation,this subject introduces a new method of directional cumulative deformation work for measuring the deformation of forgings.By calculating the deformation work accumulated in the X,Y and Z directions of all the elements in the blank model during the entire forging process.Calculate the ratio of cumulative deformation work in the X,Y,and Z directions(main deformation direction).Using the ratio of accumulated work in different directions to measure the isotropic properties of forgings.This new method can not only make up for the shortcomings of the forging ratio,but also prove whether the forging ratio is reasonable.According to the actual forging process,the method of axial forging and cross forging are formulated.Established integral forging and segment forging model using ABAQUS finite element software.The actual forging blank size is ?50O×1000mm,this paper uses a scale-down approach,the size of the blank model is reduced to ?100×200mm,and the reduction ratio is 1:5.The forging process of 3Cr2MnNiMo plastic mold steel was simulated by axial forging method and cross forging method respectively.In the overall forging model,the temperature field and stress field distribution of the billet are more uniform using the axial forging method with two upsetting and two stretching.The possibility of crack generation is small,and the forming quality of the forging surface is high.The average ratio of the cumulative deformation work reached 0.775,Therefore,two upsetting and two stretching of the axial forging method which forging ratio is 8,that is determined by the integral forging model,which is a forging technique for improving the isotropic of forgings.In the segmented forging model after the delamination of the blank,the forming quality of the axial forged forgings is still high.The direction cumulative deformation work ratio of 3Cr2MnNiMo plastic mold steel is reached 0.930.Moreover,the forming quality and isotropic properties of the two upsetting and two stretching process are higher than the one upsetting and one stretching process.It can be concluded from the segmented forging model,two upsetting and two stretching of axial forging method which forging ratio is 8,that can make the plastic mold steel obtain highly isotropic.Analyszed of the simulation results of the overall forging model and the segmented forging model.Developed an isotropic forging technology.When the plastic mold steel is forged,two upsetting and two stretching of axial forging method which upsetting ratio and stretching ratio of 2,and total forging ratio of 8,which is a forging technique that can make 3Cr2MnNiMo plastic mold steel obtain high forming quality and high isotropicity.