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High- and very high-cycle plain fatigue resistance of shot peened high-strength aluminum alloys: The role of surface morphology |
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| Affiliation: | 1. Mechanical Engineering Department, Bu-Ali Sina University, Hamedan, Iran;2. School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran;1. IRT-M2P, 4 Rue Augustin Fresnel, 57070 Metz, France;2. University of Lyon, ENISE, LTDS CNRS UMR 5513, 58 Rue Jean Parot, 42000 Saint-Etienne, France;3. Faculty of Engineering, Loramendi 4, Mondragon University, 2500 Arrasate, Spain;4. Naval Group, CESMAN, Technocampus Ocean, 5 rue de l’Halbrane, 44340 Bouguenais, France |
| Abstract: | The present paper is aimed at investigating the effect of shot peening on the high and very-high cycle plain fatigue resistance of the Al-7075-T651 alloy. Pulsating bending fatigue tests (R = 0.05) were carried out on smooth samples exploring fatigue lives comprised between 105 and 108 cycles. Three peening treatments were considered to explore different initial residual stress profiles and surface microstructural conditions. An extensive analysis of the residual stress field was carried out by measuring with the X-ray diffraction (XRD) technique the residual stress profile before and at the end of the fatigue tests. Fatigue crack initiation sites were investigated through scanning electron microscopy (SEM) fractography. The surface morphology modifications induced by shot peening were evaluated using an optical profilometer. The influence of surface finishing on the fatigue resistance was quantified by eliminating the surface roughness in some peened specimens through a tribofinishing treatment. The capability of shot peening to hinder the initiation and to retard the subsequent propagation of surface cracks is discussed on the basis of a model combining a multiaxial fatigue criterion and a fracture mechanics approach. |
| Keywords: | Shot peening Very high-cycle fatigue Al-7075-T651 Residual stresses Tribofinishing |
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