The Mechanism of Critical Strain of Serrated Yielding in Strain Rate Domain

The mechanism of the critical strain of serrated yielding is studied via tension tests at various strain rates. Before the critical strain, it is deduced that dislocations are not pinned at high strain rates, and dislocations at low strain rates are pinned but cannot escape. The critical strain depends on the first pinning process at high strain rates and on the first unpinning process at low strain rates. The calculated results based on the two criteria are in good consistency with the experiment.