Effect of ultrasonic shot peening on the surface defects of thin struts built by electron beam melting: Consequences on fatigue resistance

T. Persenot , A. Burr , E. Plancher (1) , J.-Y. Buffiere (2) , R. Dendievel (1) , G. Martin (1)

1 SIMaP - Science et Ingénierie des Matériaux et Procédés
2 MATEIS - Matériaux, ingénierie et science [Villeurbanne]

Ti-6Al-4V thin struts, built by selective electron beam melting have been submitted to hot isostatic pressing and further processed with ultrasonic shot peening to investigate the effect of this surface treatment on surface defects. The consequence of those surface defects on the fatigue resistance of thin struts has been evaluated before and after treatment. X-ray microtomography has been used to track the defect population with repeated scans before and after ultrasonic shot peening as well as after fatigue tests conducted to failure. Our results show that the fatigue resistance of surface-treated struts (measured at 105 cycles) is doubled compared to the fatigue resistance of struts with an as-built surface. This enhancement in fatigue resistance is attributed to a refinement of the sub-surface microstructure, to the introduction of local compressive residual stresses and to a significant surface smoothing effect induced by ultrasonic shot peening. Ultrasonic shot peening fails to “heal” the most tortuous surface defects observed in the as-built condition, leaving residual defects in the sub-surface region. The presence of those residual surface defects limits the fatigue resistance when compared to struts with a machined surface. © 2019 Elsevier B.V.

Mots clés: Residual stresses; Shot peening; Struts; Surface defects; Surface treatment; Ternary alloys; Titanium alloys; Tomography; Ultrasonic testing; Vanadium alloys; X rays; Compressive residual stress; Surface resistance; X ray microtomography; Ultrasonic shot peening; Selective electron beam melting; Significant surfaces; Fatigue properties; Machined surface; Defect population; 3D printers; Aluminum alloys; Electron beam melting; Electron beams; Fatigue of materials; Fatigue testing; Hot isostatic pressing

Domaines: Matériaux

T. Persenot, A. Burr, E. Plancher, J.-Y. Buffiere, R. Dendievel, et al.. Effect of ultrasonic shot peening on the surface defects of thin struts built by electron beam melting: Consequences on fatigue resistance. Additive Manufacturing, 2019, 28, pp.821-830. ⟨10.1016/j.addma.2019.06.014⟩. ⟨hal-02405429⟩