Research On Trans-scale Model And Thermal Deformation Behavior Of 2209 Duplex Stainless Steel

Duplex stainless steel,with its excellent ferritic and austenitic properties,has become a new favorite in the steel industry due to its enhanced durability and corrosion resistance.However,during the deformation process of dual-phase stainless steel,there exists an uneven distribution of stress and strain between the two phases,which may lead to internal cracks and ultimately compromise the quality of the product.These shortcomings have hindered the widespread application and development of duplex stainless steel.Therefore,it is of great significance to study the softening mechanism of dual-phase stainless steel,summarize the evolution of the two-phase structure,explore the coordination of deformation between the two phases,and analyze the cracking mechanism in order to optimize the processing technology of dual-phase stainless steel and improve its structural properties.This article presents a study on the thermal compression behavior of cast2209 dual-phase stainless steel.The true stress-strain relationships under different temperature and strain rate conditions were obtained through experiments,and a modified Johnson-Cook constitutive model was established.By analyzing the microstructure of 2209 duplex stainless steel steel under different deformation conditions and studying its true stress-strain relationship,the softening mechanism and strain distribution law were obtained.A sub-model of 2209 dual-phase stainless steel was established using Neper software,and the proportion of the two phases at high temperatures was controlled by a Python script.Using sub-modeling technology,finite element simulation analysis was carried out by coupling the sub-model with the macroscopic thermal compression model to investigate the deformation behavior of the ferritic and austenitic phases at high temperatures.The experimental results show that the volume fraction of ferrite and austenite phases in 2209 dual-phase stainless steel is more affected by deformation temperature and less affected by strain rate.With the increase of deformation temperature and the decrease of strain rate,the proportion of austenite phase gradually decreases while the proportion of ferrite phase gradually increases.According to the EBSD data analysis under different conditions,when the deformation temperature is continuously increased and the strain rate is decreased,the overall micro-strain of the material is improved,and the distribution of micro-strain becomes more uniform,and the proportion of recrystallized grains becomes larger and larger.When the deformation temperature is constant,the rheological curve at low strain rates is a dynamic recrystallization curve.With the increase of strain rate,the curve gradually transitions to a dynamic recovery curve.When the strain rate is low,the flow stress increases to a peak and then decreases with the increase of strain,ultimately reaching a stable state.When the strain rate is high,the flow stress increases to a peak and then tends to be stable.Under the same strain rate,the flow stress gradually decreases with the increase of deformation temperature,and under the same strain rate,the dynamic recrystallization effect weakened and the dynamic recovery effect strengthened,and the curve type gradually transforms into a dynamic recovery curve.By simulating the compression deformation process of 2209 duplex stainless steel steel under high temperature conditions,it was found that the relatively soft ferrite phase bears more strain during deformation.Due to the different deformation mechanisms between the two phases,the deformation is not coordinated between the two phases,and stress concentration is prone to occur at the phase boundary,which can lead to material failure under severe conditions.