Effect of mn-dispersoid on the low-cycle fatigue life of Al-Zn-mg alloys

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.…”

Microstructure of 7N01 Aluminum Alloy Microalloyed with Er and Zr in the Homogenization Process

“…For example, the Cr-containing particles precipitated during the homogenization process, improved the quenching sensitivity of the alloy. The Mn-containing particles could hinder the dislocation motion and delay the generation of fatigue crack [6][7][8].…”