Effect of strain rate in severe plastic deformation on microstructure refinement and stored energies

Abstract

The interplay of large strain and large strain-rate during high rate severe plastic deformation (HR-SPD) leads to dynamic temperature rise in situ that engenders a recovered microstructure whose characteristics is not just a function of the strain, but also of the strain-rate and the coupled temperature rise during the deformation. In this paper, we identify three classes of microstructures characterized by multi-stage recovery phenomena, that take place during the high strain-rate SPD of Cu. It is found that the first stage of this recovery is similar to the first stage of static recovery which is characterized mainly by annihilation of dislocations. Second stage starts around 360K and was characterized by dislocations getting arranged in tight cell boundaries and eventually into sub-grain. Recovery stages were found to be followed by a stage of grain growth and recrystallization when the temperature in the deformation zone approaches 480K.

User‐independent EBSD parameters to study the progress of recovery and recrystallization in Cu–Zn alloy during in situ heating

“…Similar observations have been made in the past correlating displacement shift complete (DSC) data with the LAGB fraction (Shekhar et al, 2011). This particular fact indicates that there should be a decrease, although very small, in the dislocation density and hence stored energy inside the individual deformed grains.…”

“…This particular fact indicates that there should be a decrease, although very small, in the dislocation density and hence stored energy inside the individual deformed grains. Similar observations have been made in the past correlating displacement shift complete (DSC) data with the LAGB fraction (Shekhar et al, 2011). As mentioned in the earlier section, recovery phenomenon is observed during in situ heating up to 450°C above which recrystallization initiated in some of the grains, which will be discussed in later sections.…”

Osteoblast cell response to oxide films formed on nanograin 316L stainless steel obtained by two-dimensional linear plane-strain machining

“…The average grain size of 316L stainless steel is about 22 mm while after plane-strain machining, it reduces to nanometer scale (e.g., 42 nm Table 1 List of samples prepared by linear plane-strain machining (LSM) technique with different rake angles (i.e., 0°, 20°and 40°) and after surface treatment (i.e., chemical treatment, thermal treatment) (Chem: chemical treatment, Therm: thermal treatment and N: none). in 0°rake angle) [11]. XPS spectra revealed no change in the chemical composition of the surface after SPD process of the plane-strain machining implying that refining the average grain size down to nanoscale range did not change the chemical composition of grown oxides.…”

Effect of Surface Mechanical Treatments on the Microstructure-Property-Performance of Engineering Alloys

“…There were no twins and stacking faults observed in the surface layer [153]. Shekhar et al [154] studied the behavior of strain rate on the interface boundaries and refinement and quantified the volume fraction of low angle and high angle grain boundaries. The advanced characterization, such as EBSD/TEM characterization, can distinguish the fraction of twin boundaries and atomic misorientation or kernel average misorientation [155].…”