Effect of shot peening conditions on the fatigue life of additively manufactured A357.0 parts

Fatigue performance can be a critical attribute for the production of structural parts or components via additive manufacturing (AM). In comparison to the static tensile behavior of AM components, there is a lack of knowledge regarding the fatigue performance. The growing market demand for AM implies the need for more accurate fatigue investigations to account for dynamically loaded applications. A357.0 parts are processed by laser-based powder bed fusion (L-PBF) in order to evaluate the effect of surface finishing on fatigue behavior. The specimens are surface finished by shot peening using φ = 0.2 and φ = 0.4 mm steel particles and φ = 0.21-0.3 mm zirconia-based ceramic particles. The investigation proves that all the considered post-processing surface treatments increase the fatigue resistance of as-built parts, but the effect of peening with φ = 0.4 mm steel particles or with ceramic particles is more pronounced than that of peening with φ = 0.2 mm steel particles, although this treatment has the same Almen A value as the ceramic one. The surface morphology and the crack surface of the samples are also investigated.