Effects of strain rate and mean strain on cyclic behavior of aluminum alloys under isothermal and thermo-mechanical fatigue loadings

Influences of strain rate on the low cycle fatigue behavior of gravity casting Al alloys

“…Several work on the LCF behavior of metals, such as steels [9,10] and stainless steels [11], has been done in trying to understand the interaction between the fatigue loading and strain rates. To the author's best knowledge, only one group studied the cyclic deformation behavior in aluminum alloys (Al-Si alloys) with various strain rates, where the LCF lifetime at Materials Characterization 107 (2015) 239-248 523 K increased with the increase of strain rate, due to higher plastic strain at lower strain rate [12]. Although there are limited reports on the LCF behaviors of Al-Si-Cu alloys, there is no detailed report regarding the effect of different strain rate on the LCF of Al-Si-Cu alloys.…”

Effect of Strain Rate on the Deformation Behaviour of A356-T7 Cast Aluminium Alloys at Elevated Temperatures

“…The strain rate also has an effect on the isotropic hardening/softening behaviour, with the material exhibiting a higher isotropic hardening rate at room temperature and a higher isotropic softening rate at 200 • C for the tests with a strain rate of 10% s −1 , as can be observed from the change in plastic strain amplitudes with cyclic loading as presented in Figure 13. High-temperature fatigue tests of A356 alloy at 200 • C by Azadi [16] indicated a similar increased softening behaviour of the alloy for the completely reversed tests. At 150 • C, the material exhibits insignificant isotropic hardening at both tested strain rates.…”

“…The tested material exhibits a clear increase in the number of cycles to failure at higher strain rates for identical load and test temperature conditions. The study by Azadi [16] showed an increase in the fatigue lifetime of A357 alloy with increasing strain rates owing to reduced cyclic plastic strain amplitudes. A similar behaviour is observed for the tested A356-T7 + 0.5% Cu alloy, as we observe higher plastic strain amplitudes at lower strain rates, as can be observed in Figure 13.…”

“…Studies by Azadi [16] showed that for A356 cast aluminium alloys, the strain ratio had no significant influence on the low cycle fatigue (LCF) lifetime of the alloy. For completely reversed fatigue tests at 200 • C, the material had an LCF lifetime of 2317 ± 663 cycles at a loading frequency of 1% s −1 .…”

“…Pinto et al [3] made a comparative study on the fatigue behaviour of three aluminium alloys including AS7GU alloy (that was similar in composition to the A356 + 0.5 wt % Cu alloy of interest in this study) and observed that it exhibited a superior ductility and high cycle fatigue behaviour compared to the other tested aluminium alloys along with a lower scatter in the number of cycles to failure owing to the lower copper content in the alloy (0.5%). Azadi [16] studied the effect of strain rates and mean strains on the cyclic deformation behaviour of two different aluminium-silicon-magnesium alloys, A356 and A357. The author observed that for low cycle fatigue tests at 200 • C and a strain amplitude of 0.4%, the mean strains had no influence on the number of cycles to failure of the A356 alloy.…”