Study On The Flow Stress Model Of IN718 Alloy In Hot Continuous Rolling Process

With the rapid development of the aeronautic and astronautic industry,requirements for the performance and size accuracy of IN718 alloy workpieces are becoming higher and higher. IN718 alloy has good plasticity due to the fcc structure,and high deformation resistance during hot deformation process due to the high alloying. As a main production way of IN718 alloy, hot continuous rolling has high efficiency and high yield for production, good quality for products. However, the flow stress of the alloy during the hot continuous rolling process has a direct impact on the rolling force, which needs to be paid more attention to.In this paper, the flow stress model of IN718 alloy hot continuous rolling process is constructed based on the stress-strain curves obtained from single pass and double pass single axial compression experiments, a finite element analysis model of IN718 alloy during hot continuous rolling process has been established using the thermo-mechanical coupled rigid-plastic finite element method on the software MSC.Marc, and the Fortran language is used to compile the flow stress model of hot continuous rolling process, which is embedded into the finite element model. The specific contents are as follows:(1) The effect of strain rate, deformation degree and deformation temperature on the flow stress is analyzed by the experimental measurement of the true stress-strain curve of IN718 alloy, and the flow stress model of the hot rolling process is constructed.(2) Based on the experimental results of single axis compression of IN718 alloy,the softening rate model due to sub dynamic recrystallization is constructed. Based on the flow stress model and softening rate model, the flow stress model of alloy’s hot continuous rolling process is established.(3) The thermal-mechanical coupled analysis model including temperature field model, flow stress model and softening rate model of IN718 alloy’s hot continuous rolling process is established using the rigid-plastic finite element method on thesoftware MSC.Marc.(4) According to the results of numerical simulation, the workpiece center node is selected as the analysis object. The variation law of equivalent strain, equivalent strain rate, equivalent stress and rolling force of IN718 alloy during hot continuous rolling is studied, the influence of different rolling speed on the rolling force is analyzed, and the flow stress model and the pass time softening rate model are verified.