The possible role of point defects during plastic deformation of IF steel

Abstract

The generation of point defects and debris during plastic deformation of face-centered cubic metals and their dynamic manifestations during strain rate change tests are synopsized. In contrast the point defect generation in body-centered cubic metals have not been actively studied primarily because at low temperatures, starting at ambient, the lattice friction and the interstitial solute effects are so large. Our discovery of a method to lower the interstitial solute content in the matrix to below 1 ppm mass in titanium stabilized interstitial free (IF) steel to produce ultra-fine grain sizes by continuous recrystallization offers an opportunity to examine the issue of point defect production in pure iron. The strain rate sensitivity, S, measured in the range of 0.18–0.28 homologous temperature do not indicate the presence of dynamically recoverable debris. However, the magnitude of S is greatly affected by the concentration level of the interstitial carbon. A possible explanation for these observations is that the generated debris are glissile interstitial loops, the mobility of which is impeded by carbon.