Development And Application Of Multi-Scale Simulation Software Based On DEFORM-3D For Hot Forging

Forgings are always the key components of major equipment which need to meet their high mechanical performance requirements by hot forging.Because hot forging has two main characteristics of deformation and denaturation,so it is needed to study the macroscopic changes and microstructural evolution of the forgings uniformly in order to obtain the optimal process parameters,then improve the performance of the forgings.It will require a very high cost to rely solely on the physical experiment,and some internal physical phenomena are difficult to be observed,but the numerical simulation technology can solve these problems well.Therefore,it has very important engineering significance to develop a multi-scale numerical simulation software to study the macroscopic changes and microstructural evolution,then use the software to control "the whole process" of the forgings and optimize process of the forgings in order to achieve the purpose of controlling shape and performance.In this paper,the macroscopic changes and microstructural evolution of hot forging was analyzed by using the method of quasi coupling analysis.According to the condition where the temperature and strain rate are constantly changing,the relevant models of dynamic recrystallization,static recrystallization and grain growth were discretized to adapt the calculation of deformation incremental step.The mutual influence between the front and back passes of multi-pass hot forging was studied,and the calculation method of the residual strain and modified strain were given.The evolution model of void type defects and the hot forming cracking model were discretized to adapt the calculation of the incremental step.The user subroutines of DEFORM-3D which include the flow stress subroutine and multi-scale simulation subroutine for hot forging were written in Fortran language.Multi-pass hot forging simulation software was developed by using C# language in Visual Studio software.The flow stress subroutine and multi-scale simulation subroutine for hot forging were joint compiled,and then imported into the commercial finite element software DEFORM-3D through multi-pass hot forging simulation software,finally,the multi-scale numerical simulation of multi-pass hot forging was realized.The numerical simulation accuracy of the microstructural evolution,void closure and hot forming cracking were verified through the double pass cogging experiment of cuboid specimen,upsetting and cogging experiments of PbSb3 specimens which have void inside and hot compression experiment of tapered specimen.The appropriate parameters for the cogging process of the rectangular billet were obtained through numerical simulation of the deformation of SA508-3 steel rectangular billet under different process parameters.The cogging process of SA508-3 steel ingot was simulated by using the optimized process parameters,the simulation results show that the high quality forgings can be obtained by using the conventional forging method to realize the cogging of SA508-3 steel ingot.The appropriate parameters for the final forging process of the regulator head were obtained through numerical simulation of the final forging of regulator head under different process parameters.The whole final forging process of the regulator head was simulated by using the optimized process parameters,the simulation results indicate that the possibility of cracking on the the regulator head is not big in the final forging,and the microstructure is very inhomogeneous which may be homogenized by reducing the heating time,decreasing the forging temperature and increasing the reduction per anvil.