Thermal and microstructural softening behaviors during dynamic recrystallization in 3Cr20Ni10W2 alloy

In the present study, the dynamic flow softening behaviors and grain size evolution during dynamic recrystallization (DRX) in 3Cr20Ni10W2 alloy were investigated by quantization calculation based on the data from hot compression tests over a wide range of temperature and strain rate. A new modified algorithm considering strain effect is presented for conducting the adiabatic heating corrections in stress-strain curves. The corrections in flow stress for deformation heating vary in the range of 4.76-69.69 MPa, and increase with increasing strain rates and decreasing temperatures. The 3D map which reveals the ratio of thermal softening (RTS, defined as the magnitude of thermal softening to the peak stress) at different strains as a function of strain rate and deformation temperature is developed. The results show that RTS increases with increasing strain rates and decreasing temperatures in general, whereas it is more sensitive to strain rates. Meanwhile, the ratio of microstructural softening (RMS) is introduced as an indicator to quantify the degree of microstructural softening by DRX. The 3D RMS map indicates that microstructural softening degree increases with decreasing strain rates and decreasing temperatures under the overwhelming majority of conditions. Moreover, a superimposed contour map of the average grain size over RMS map is constructed at the true strain of 0.916. The results indicate that the grain size distribution is correlated with combined effect of thermal softening by deformation heating and microstructural softening by DRX.