: The mechanical properties of S32760 duplex stainless steel under dynamic loading conditions at high strain rates are significantly different from those under quasi-static conditions. As a result of large strain, high strain rate, and high temperature, the analysis of the cutting process needs to factor in the influence of the viscous behavior of the material on the plastic deformation process. Based on the viscous effect of the two phases and the mixing rule, a mechanical threshold stress (MTS) constitutive model of S32760 duplex stainless steel considering the viscous effect is established to analyze the effect of strain rate on flow stress. An inverse identification method of the constitutive parameters based on Oxley’s theory is proposed. The constitutive parameters of S32760 duplex stainless steel were reversely modified using an equal shear zone model and an orthogonal cutting experiment. The results show that the viscosity of the austenite phase was greater than that of the ferrite phase, and the strain rate had the greatest influence on the viscosity effect in the constitutive model. The prediction error of the constitutive model constructed in this manuscript was less than 4%, which had high accuracy.

Identiﬁcation of the Constitutive Parameters of Viscosity and the Prediction of the Cutting Force of S32760 Duplex Stainless Steel under a High Strain Rate

The mechanical properties of S32760 duplex stainless steel under dynamic loading conditions at high strain rates are significantly different from those under quasi-static conditions. As a result of large strain, high strain rate, and high temperature, the analysis of the cutting process needs to factor in the influence of the viscous behavior of the material on the plastic deformation process. Based on the viscous effect of the two phases and the mixing rule, a mechanical threshold stress (MTS) constitutive model of S32760 duplex stainless steel considering the viscous effect is established to analyze the effect of strain rate on flow stress. An inverse identification method of the constitutive parameters based on Oxley's theory is proposed. The constitutive parameters of S32760 duplex stainless steel were reversely modified using an equal shear zone model and an orthogonal cutting experiment. The results show that the viscosity of the austenite phase was greater than that of the ferrite phase, and the strain rate had the greatest influence on the viscosity effect in the constitutive model. The prediction error of the constitutive model constructed in this manuscript was less than 4%, which had high accuracy.

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Identification of the Constitutive Parameters of Viscosity and the Prediction of the Cutting Force of S32760 Duplex Stainless Steel under a High Strain Rate



The essence of plastic deformation in cutting processing is the movement and proliferation of dislocations. By increasing the density of dislocations, the material’s flow stress will inevitably increase by rising the strain rate.



The three regions are divided quantitatively as thermal activation stage (101-3×103), non-thermal stage (10-3-101), and dislocation damping stage (above 3×103). Analyzing the chip metallographic diagram of the cutting process, it is believed that the strain rate effect is caused by two reasons.



It is divided into three areas based on the speed of growth and the control mechanism presenting a more de-tailed and vivid explanation of these three areas. Using Hopkinson pressure bar (SHPB), the strain rate effect of duplex stainless steel S32760 is studied. T



The first is the greater austenite deformation caused by the austenite deformation in S32760 compared to the ferrite softening effect and the insufficient softening effect in the plastic deformation of the material.



The second is the grain refinement caused by the adiabatic shear zone from the deformation zone to the transi-tion zone making it difficult for dislocations to start slipping and increasing the flow stress.


Heqing Zhang

Papers

Effects of strain Rate on Cutting of Duplex Stainless Steel S32760

Identiﬁcation of the Constitutive Parameters of Viscosity and the Prediction of the Cutting Force of S32760 Duplex Stainless Steel under a High Strain Rate

Identification of the Constitutive Parameters of Viscosity and the Prediction of the Cutting Force of S32760 Duplex Stainless Steel under a High Strain Rate