Fatigue Behavior of the Al-5wt%Si-2.5wt%Cu alloy produced by Combining Grain Refining Techniques: Electromagnetic Stirring with Al-5wt%Ti-1wt%B

This article studies the fatigue behavior of the Al-5wt%Si-2.5wt%Cu alloy. The effect of combining techniques of chemical grain refining (Al-5wt%Ti-1wt%B alloy) added to electromagnetic stirring, CGR+EMS, is demonstrated in this work. This combination produced a microstructure with reduced grain size (121 ± 20 µm) when compared with the raw material produced only by electromagnetic stirring, EMS, (213 ± 38µm), with grain refiner Only, CGR, (184 ± 23 µm) or Without any Grain Refining Technique (WGRT) (413 ± 96 µm). The condition produced by associating electromagnetic stirring with the Al-5wt%Ti-1wt%B grain refiner presented the smallest grain size and less porosity. Thus, conditions CGR+EMS and WGRT were chosen to continue the evaluation of the mechanical performance of the studied alloy via tensile tests, whose results for ultimate tensile stress, yield strength and elongation were, respectively, WGRT/ CGR+EMS, UTS = 160.3 ± 9.5 / 208 ± 10 MPa, YS (0.2%) = 110 ± 2 / 135 ± 3.5 MPa and ε(%) =3.2 ± 0.1 / 2.9 ± 0.1. Fatigue tests were conducted via the staircase method. The average estimate of fatigue strength for a given life (10⁷ cycles) and the standard deviation calculated for WGRT and CGR+EMS condition were, respectively, ${\widehat{\mu }}_y$= 60.1 MPa / 71.6 MPa and ${\widehat{\sigma }}_y$= 3.30 / 6.42.

Keywords:
fatigue; staircase method; grain refining; electromagnetic stirring