| The purpose of this study is to investigate the effect of thermo-mechanical treatment (TMT) on the low cycle fatigue behavior an 7050 Al alloy. During low cycle fatigue tests, the conventional T6 and T74 treated specimens showed cyclic softening, where as the TMT resulted in cyclic hardening behavior. At strain amplitude of 1.1%, conventionally heat-treated specimens showed longer fatigue life than the TMT ones At total strain amplitude less than 0.9%, however, the TMT showed longer fatigue life than the T6 and T74 treatments due to the reduction of mean free path of dislocations. The reduction of mean free path could be ascribed to an interaction between matrix precipitates and dislocations introduced during the TMT process, strengthening due to precipitate free zone (PFZ) and the formation of grain boundary steps. |
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