Anneal-hardening behavior of Cr-Fe-C alloy deposits prepared in a Cr³⁺-based bath with Fe²⁺ ions

Cr-Fe-C alloy deposits were successfully prepared on high-carbon tool steel in a Cr3+-based electroplating bath containing Fe²⁺ ions and suitable complex agents. A Cr-based alloy deposit was obtained with an electroplating current density higher than 25 Adm^-2, and a Fe-based alloy deposit was obtained using a current density of 20 Adm^-2. Following electroplating, these alloy deposited specimens were annealed via rapid thermal annealing (RTA) at 500 °C for different periods up to 30 s. The experimental results show that Cr- and Fe-based alloy deposits could be significantly hardened after RTA at 500 °C for a few seconds. The maximum hardness was that of the Cr-Fe-C alloy deposit annealed at 500 °C for 10 s. The maximum hardness of 1205 Hv was detected from the annealed Cr-based alloy deposit prepared with 30 ASD. The hardening mechanism of annealed Cr- and Fe-based alloy deposits is attributed to the precipitation of C-related membranes. The hardness values of the annealed Cr- and Fe-based alloy deposits increase with the increasing degree of crystallization of the C-related membranes.