PSI - Issue 18

Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2019) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000–000 Available online at www.sciencedirect.com ScienceDirect

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Procedia Structural Integrity 18 (2019) 119–128

25th International Conference on Fracture and Structural Integrity Investigation on fatigue strength of sand-blasted DMLS-AlSi10Mg alloy Andrea Avanzini a , Davide Battini a , Marcello Gelfi a , Luca Girelli a , Candida Petrogalli a , Annalisa Pola a , Marialaura Tocci a * a Department of Mechanical and Industrial Engineering, University of Brescia, Via Branze 38, 25123, Brescia, Italy Abstract Fatigue resistance of Direct Metal Laser Sintered (DMLS) AlSi10Mg alloy after sand-blasting was investigated in the present study. A preliminary characterization of the samples was carried out in order to identify material microstructure, surface roughness and superficial residual stresses. It was found that the applied post-processing treatment was responsible for a strong decrease in average surface roughness as compared to the as-built condition and induced compressive residual stresses on the samples surface. Axial fatigue tests were performed in both finite and infinite (i.e. 2x10 6 cycles) life regimes and the obtained results were compared with literature values for the same alloy after various post-treatments, including heat treatment, machining, polishing and shot peening. A general positive effect of the applied sand-blasting on fatigue resistance was observed. This, coupled with the improvements of surface finishing, encourages the use of sand-blasting as a simple and effective post-treatment. Finally, observations of the fractured surfaces allowed also the identification of porosities located on the surface as the main crack initiation sites. Once the crack has started, it moves along a large flat area, as typical of fatigue propagation, with a small final overload region. 25th International Conference on Fracture and Structural Integrity Investigation on fatigue strength of sand-blasted DMLS-AlSi10Mg alloy Andrea Avanzini a , Davide Battini a , Marcello Gelfi a , Luca Girelli a , Candida Petrogalli a , Annalisa Pola a , Marialaura Tocci a * a Department of Mechanical and Industrial Engineering, University of Brescia, Via Branze 38, 25123, Brescia, Italy Abstract Fatigue resistance of Dire t Metal Laser Sintered (DMLS) AlSi10Mg alloy aft r sand-blasting was investigated in the pres nt study. A preliminary characterization of the samples was carried ut in order to id ntify material microstructure, surface roughness nd superficial residual stresses. It was f und that the applied post-processing treatment was responsible f r a strong decrease in average surfac roughness as compared to the as-built condition and induced compr ssiv residual stresses on the samples surface. Axial fatigue tests were performed in both finite and infinite (i.e. 2x10 6 cycles) life regimes nd the obtained results were compared with literature values for the same alloy after various post-treatments, including heat treatment, machining, polishing and shot peening. A general positive effect of the applied sand-blasting on fatigue resistance was obs rved. This, coupled with the improvements of surface finishing, encourages t use of sand-blasting as a simple and effective post-treatment. Finally, observations of the fractured surfaces allowed also the id ntification of porosities located on the surface as the main crack initiation sites. Once the crack has started, it moves along a large flat area, as typical of fatigue propagation, with a small final overload region.

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo.

Keywords: DMLS; AlSi10Mg; Sand-blasting; Fatigue; Porosity Keywords: DMLS; AlSi10Mg; Sand-blasting; Fatigue; Porosity

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. * Marialaura Tocci. Tel.: +39.030.3715415; fax: +39.030.3702448 E- address: m.tocci@unibs.it * Marialaura Tocci. Tel.: +39.030.3715415; fax: +39.030.3702448 E- address: m.tocci@unibs.it

2452-3216  2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. 10.1016/j.prostr.2019.08.146