Effect of Mn dispersoid on the fatigue crack propagation of Al-Zn-Mg alloys

In-situ observation of the fracture process in Al–Zn–Mg–Cu alloys

“…Particles ahead the crack tip deviate the crack path, and its path becomes longer due to the meandering effect. This explanation is in general accordance with reports in the literature [41,42]. As clearly shown in Fig.…”

Microstructure and Fatigue Properties of AlZn6Mg0.8Zr Alloy Subjected to Low-Temperature Thermomechanical Processing

“…Frequently, these cracks are spread in different directions, which may indicate the presence of a probable obstacle, e.g., in the form of precipitations, or the case where paths of cracks propagation run along grain boundaries (Figure 13d). Similar effects were observed by Park, Jo et al in their works [13,14]. In Al-Zn-Mg alloy with 0.5% concentration of Mn, the paths are different from those observed in alloys without this addition.…”

Microstructural and Fractographic Analysis of Plastically Deformed Al-Zn-Mg Alloy Subjected to Combined High-Cycle Bending-Torsion Fatigue

“…A characteristic feature of scrap samples after bending with torsion with a stress amplitude of σ a = 159 MPa and τ a = 79 MPa is the presence of irregularly shaped jogs, reflecting the secondary fatigue cracks (Figure 9b). The direction change of crack propagation is a common phenomenon in alloys containing dispersive particles of secondary phases, as reported by Jo, Park et al [11,12]. This is caused by a crack front "avoiding" precipitation, leading to the curvature of the crack path.…”

“…In the case of the samples loaded with lower stresses (σ a = 135 MPa, τ a = 68 MPa) in the high-cycle range, systems of jogs of cleavage planes are visible, with evidence of plastic deformation on the surface of jogs (Figure 9c). Loading the samples particles of secondary phases, as reported by Jo, Park et al [11,12]. This is caused by a crack front "avoiding" precipitation, leading to the curvature of the crack path.…”

“…Moreover, literature on the aspects of fatigue strength of 7000 series alloys are usually narrowed to cyclic tensile-compressive loads. Jo et al [11] and Park et al [12] investigated the effect of Mn addition to the Al-Zn-Mg alloy on the formation of dispersive particles, affecting the resistance of the alloys to fatigue cracking during cyclic tension-compression. Similarly, Deng et al [13] studied strength properties of friction-welded joints in the 7050 alloy in tension-compression fatigue tests.…”