Kinetics of Damping Decay during Strain-Ageing in an Fe–0.05% C Alloy

Abstract Carbon strain-ageing has been studied in a vacuum-melted Fe–0·05% C alloy heat-treated to contain ∼6, 14, and 150 ppm carbon in solution. Damping and electron microscopy were used to follow the progress of ageing at 40° C (313 K) after 10% elongation. The decay of damping during strain-ageing was resolved into two components: Snoek damping and dislocation damping. The decay of Snoek damping obeyed the kinetics predicted by Meisel for segregation of carbon to atmospheres about dislocations. The decay in amplitude-independent dislocation damping followed the damping kinetics predicted by Granato et al. Hence, the decay rates of both types of damping support the theory that carbon atoms migrate to, and pin, dislocations during the initial stage of ageing. Furthermore, the Snoek damping results imply that migration of carbon to dislocations continues long after the dislocations are fully pinned. By transmission electron microscopy, small dark spots were detected in the matrix of highly supersaturated...