Effect of Density and Surface Quality on Fatigue Behavior of LPBF 316L Steel
Jaskari, Matias; Hamada, Atef; Karjalainen, Pentti; Järvenpää, Antti (2023-07-30)
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Sisältö avataan julkiseksi: 30.07.2025
Springer
30.07.2023
Jaskari, M., Hamada, A., Karjalainen, P., Järvenpää, A. (2023). Effect of Density and Surface Quality on Fatigue Behavior of LPBF 316L Steel. In: Zarbane, K., Beidouri, Z. (eds) Proceedings of CASICAM 2022. CASICAM 2022. Springer Tracts in Additive Manufacturing. Springer, Cham. https://doi.org/10.1007/978-3-031-32927-2_22
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© 2023 The Author(s), under exclusive license to Springer Nature Switzerland AG. This is a post-peer-review, pre-copyedit version of an article published in Proceedings of CASICAM 2022. The final authenticated version is available online at: https://doi.org/10.1007/978-3-031-32927-2_22
https://rightsstatements.org/vocab/InC/1.0/
© 2023 The Author(s), under exclusive license to Springer Nature Switzerland AG. This is a post-peer-review, pre-copyedit version of an article published in Proceedings of CASICAM 2022. The final authenticated version is available online at: https://doi.org/10.1007/978-3-031-32927-2_22
https://rightsstatements.org/vocab/InC/1.0/
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:oulu-202404262977
https://urn.fi/URN:NBN:fi:oulu-202404262977
Tiivistelmä
Abstract
Metal additive manufacturing (AM) is a fabrication method to effectively produce optimized parts for various applications. Laser powder bed fusion (LPBF) is currently one of the most common AM methods. For efficiency, shorter throughput times are searched by increasing the deposited layer thickness for instance. Faster processing can, however, lead to formation of defects such as voids in the structure, which in turn may result in impaired fatigue resistance, even in the instance that the static properties are unaffected. The effect of the material density and surface quality on the fatigue behavior of an AISI 316L austenitic stainless steel fabricated by the LPBF method with two different layer thicknesses (40 and 80 μm). Some samples were tensile tested, while an extensive study was performed by axial tension-compression load-controlled fatigue testing (the loading frequency 100 Hz). Samples were tested either in the as-built or electropolished condition until failure or to 10 7 cycles. Surface topography and roughness were measured using a focal imaging laser microscope and fracture surfaces were examined by a scanning electron microscope. It was found that the layer thickness during deposition affected the material density and amount of defects in the structures. However, the tensile strength was not affected significantly by these differences. The fatigue limit of both the as-built 40 um and 80 um structures as well as electropolished 80 μm structure remained below 100 MPa at 107 cycles as a result from both near surface defects or rough surface. However, the electropolished 40 μm structure exhibited an excellent fatigue limit of 240 MPa. Therefore, both the defect density and surface roughness must be controlled in order to enhance significantly the fatigue resistance of LPBF 316L.
Metal additive manufacturing (AM) is a fabrication method to effectively produce optimized parts for various applications. Laser powder bed fusion (LPBF) is currently one of the most common AM methods. For efficiency, shorter throughput times are searched by increasing the deposited layer thickness for instance. Faster processing can, however, lead to formation of defects such as voids in the structure, which in turn may result in impaired fatigue resistance, even in the instance that the static properties are unaffected. The effect of the material density and surface quality on the fatigue behavior of an AISI 316L austenitic stainless steel fabricated by the LPBF method with two different layer thicknesses (40 and 80 μm). Some samples were tensile tested, while an extensive study was performed by axial tension-compression load-controlled fatigue testing (the loading frequency 100 Hz). Samples were tested either in the as-built or electropolished condition until failure or to 10 7 cycles. Surface topography and roughness were measured using a focal imaging laser microscope and fracture surfaces were examined by a scanning electron microscope. It was found that the layer thickness during deposition affected the material density and amount of defects in the structures. However, the tensile strength was not affected significantly by these differences. The fatigue limit of both the as-built 40 um and 80 um structures as well as electropolished 80 μm structure remained below 100 MPa at 107 cycles as a result from both near surface defects or rough surface. However, the electropolished 40 μm structure exhibited an excellent fatigue limit of 240 MPa. Therefore, both the defect density and surface roughness must be controlled in order to enhance significantly the fatigue resistance of LPBF 316L.
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