Coupled influence of microstructure and atmosphere environment on fatigue crack path in new generation Al alloys

Crack growth behaviour of aluminium wrought alloys in the Very High Cycle Fatigue regime

“…7a and 8b) where the cutting mechanism of the secondary particles was most probable preferred. Similar findings were observed by Richard et al [5] who summarized the results of different studies on the fatigue long crack propagation in metallic alloys. They concluded that two intrinsic regimes (named as intrinsic stage I-like and intrinsic stage II regime) exist in high vacuum which differ significantly in respect to the crack growth mechanism.…”

“…It is a well-known fact that the humidity of ambient air deteriorates the fatigue properties of aluminium alloys compared to an inert environment [4][5][6]. In this study, the atmospheric influence on the VHCF long crack propagation in the aluminium wrought alloys EN-AW 6082 and 5083 in different material conditions is investigated.…”

“…It is assumed that water vapour as a constituent of ambient air can rapidly reach the crack tip and adsorb on newly formed surfaces that form as a consequence of the crack progression resulting in a local chemical reaction. The formation of an aluminium oxide layer leads to water reduction at the interface between the oxide and the metal leading to the deposition of chemisorbed atomic hydrogen [5,11]. A certain amount of the atomic hydrogen can diffuse through the plastically deformed zone in front of the crack tip during cyclic loading, if the crack propagation rate (below 10 -9 m/cycle) is smaller than the mean diffusion distance of hydrogen at room temperature (3 x 10 -9 m) [9,10].…”

Effect of actual and accelerated ageing on microstructure evolution and mechanical properties of a 2024-T351 aluminium alloy

“…However, Shih et al [12] showed that, for 2024 aluminium alloy, the major parameter for the precipitation of S' phase was the value of a preaging strain and not the alloying contents. Further, Richard et al [13] studied the fatigue behaviour of 2022 and 2024 alloys. They showed that the two alloys presented a similar fatigue behaviour in the propagation step despite of their differences in copper content.…”

Effect of water vapor pressure on fatigue crack growth in Al–Zn–Cu–Mg over wide-range stress intensity factor loading

“…For a wide range of K, R impacts: (a) crack closure, (b) transport of water vapor molecules within the fatigue crack [47], and (c) tensile stress-plastic strain range sensitive crack tip damage [2,4,35]. These deficiencies were recently addressed for an Al-Zn-Mg-Cu alloy [40], as well as several Al-Cu-Mg/Li alloys [48], and limited results were reported for the P H2O /f dependence of da/dN at high R and low K for Al-Li-Cu and Al-Zn-Mg-Cu alloys in several purified gas environments [39]. Generally, however, systematic measurement and modeling of the effect of environmental exposure on FCP rate is lacking for the lower-Paris to near-threshold regime (da/dN < 10 -5 mm/cycle).…”