Effect of Microstructure on High Cycle Fatigue Behavior of 211Z.X-T6 Aluminum Alloy

Abstract

In the present paper, the high cycle fatigue (HCF) of a novel 211Z.X aluminum alloy with high strength was studied under hot-rolling and as-cast states at room temperature. The effects of microstructure and distribution of precipitated phases and impurities on the mechanical properties, HCF performances, fatigue microcrack initiation, and propagation behavior of the 211Z.X alloy were studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). The HCF S–N curves, P–S–N curves and Goodman fatigue diagrams of 211Z.X alloy consisting of two microstructures were drawn. The results suggested that the fine and dispersive distribution of the second phases improved the strength of the alloy. The formation of short-bar and spherical precipitates promoted coordinated deformation of the alloy. This promoted higher microcrack initiation resistance of 211Z.X alloy with a hot rolling state than in the cast state. As a result, the HCF properties of the hot-rolling alloy were better than those of the cast alloy. In sum, these results look promising for future reliable design of engineering structures and application of new aluminum alloys.

Characterization of fatigue behavior of AA2024‐T351 aluminum alloy

“…Their size is between 10 and 100 μm through the cross section and between 100 and 1000 μm through a plane formed by a diameter and the longitudinal direction. Similar microstructure was observed in the literature 8,17 …”

“…Similar microstructure was observed in the literature. 8,17 The material also shows inclusions, mainly of Al-Cu-Fe-Mn and Al-Cu-Fe-Si-Mn. 2,4,18,19 It should be noted that in addition to the coarse intermetallic precipitates (incoherent second phase particles θ Al 2 Cu ð Þ and S Al 2 CuMg ð Þ ), there could be dispersoids, such as Mn, which can slow down or even stop the growth of the grains by exerting an anchoring force, known as the Zener force.…”

“…Many authors also focused their works on the influence of microstructural and metallurgical states on the behavior of age-hardened aluminum alloys during cyclic loading. 7,8 The analysis of cyclic behavior of aluminum alloys considering different hardening models and identifications strategies had interested many authors. One of the most used diagrams to study fatigue life is the S-N curves or Wöhler curve which describes the fatigue life span with respect to the applied stress amplitude and exhibits the fatigue endurance limit.…”

“…The evolution of damage under fatigue of various aluminum alloys have been also investigated for many years. Many authors also focused their works on the influence of microstructural and metallurgical states on the behavior of age‐hardened aluminum alloys during cyclic loading 7,8 …”