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Indexed by:期刊论文

Date of Publication:2021-01-10

Journal:MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

Volume:795

ISSN No.:0921-5093

Key Words:Magnesium alloy; Fatigue; Cyclic frequency; Ratcheting; Twinning; Slip

Abstract:The ratcheting behavior of magnesium alloy AZ31B was investigated under controlled cyclic stress at frequencies of 0.5 Hz, 1.0 Hz and 2.0 Hz. The result showed that cyclic loading accelerates strain accumulation as compared with static creep at room temperature, and the effect of cyclic frequency on strain rate d epsilon(r)/dt, represented by strain in a unit time, is of multiplicity due to the diversification of deformation mechanisms. However, strain rate d epsilon(r)/dN, represented by strain in one cycle, decreases evidently with increasing frequency at steady strain accumulative stage. High frequency promotes twinning-detwinning, and is favorable for prolonging the fatigue life in terms of cyclic number to failure. The fatigue life increases linearly with decrease of plastic strain energy density under all frequency conditions. This leads to conclude that frequency affects the fatigue life via changing plastic strain energy stored in the deformed microstructure.