Localized plastic deformation autowaves in FCC alloy with a stable phase structure

Investigations of the kinetics of localized plastic deformation fronts in aluminum alloy 1550 have been made. It has been established that in this alloy fronts of Chernov–Lüders bands (CLB) and Portevin–Le Chatelier bands (PLC) are observed. A distinctive feature of CLB fronts in this material is their discrete movement only in the phase of specimen unloading. Continuous movement of the fronts is possible here if the rate of effective stress restoration through the testing machine is greater than or equal to the rate of stress relaxation controlled by internal processes at a lower structural scale level. After the yield plateau, discontinuous yielding is realized. Nucleation sites of localized deformation fronts at this stage are predefined by CLB fronts. These fronts pass 2–3 times through the entire gauge length of the specimen. Then, at low strain rates, the load curve has a monotonic hardening section, where PLC fronts are not formed. At deformation rates ≥3.33 × 10−4 s−1 such section does not exist. In both cases, fracture occurs in the discontinuous yielding mode. The movement of localized deformation fronts is discussed within the concept of autowaves.