Fatigue strength and impact toughness dependence of powder bed fusion with laser beam-manufactured 316L stainless steel on orientation and layer thickness
Rautio, Timo; Jaskari, Matias; Keskitalo, Markku; Päkkilä, Joonas; Järvenpää, Antti (2023-11-03)
Laser Institute of America
03.11.2023
Rautio, T., Jaskari, M., Keskitalo, M., Päkkilä, J., & Järvenpää, A. (2023). Fatigue strength and impact toughness dependence of powder bed fusion with laser beam-manufactured 316L stainless steel on orientation and layer thickness. Journal of Laser Applications, 35(4), 042062. https://doi.org/10.2351/7.0001113
https://rightsstatements.org/vocab/InC/1.0/
© Copyright 2023 AIP Publishing LLC. Published under an exclusive license by Laser Institute of America. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in J. Laser Appl. 35, 042062 (2023) and may be found at https://doi.org/10.2351/7.0001113.
https://rightsstatements.org/vocab/InC/1.0/
© Copyright 2023 AIP Publishing LLC. Published under an exclusive license by Laser Institute of America. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in J. Laser Appl. 35, 042062 (2023) and may be found at https://doi.org/10.2351/7.0001113.
https://rightsstatements.org/vocab/InC/1.0/
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:oulu-202405023061
https://urn.fi/URN:NBN:fi:oulu-202405023061
Tiivistelmä
Abstract
Additive manufacturing is an enticing way of producing complex geometries and optimized parts for special applications. Even though the achievable static properties for the printed material are usually good when compared to wrought materials, in many cases dynamic properties are known to be much worse. Often, the quality is sacrificed in respect of printing speed. Furthermore, printed materials have usually anisotropic behavior, caused by the remelting and fast cooling of each deposited layer. This means that the mechanical properties need to be measured in several directions in respect of the printing direction for attaining a more holistic approach to the achieved static and dynamic behavior. As a demonstration, this study focuses on determining the properties of 316L stainless steel-manufactured with laser powder bed fusion. A comprehensive set of samples for various testing methods were manufactured to investigate the effect of the layer thickness and printing orientation on the microstructure, mechanical properties, impact strength, and fatigue life. Fatigue performance of the material was evaluated in both axial and flexural bending comparing as-built and polished surface conditions. Bending fatigue testing revealed that a fatigue limit of 100 MPa at best can be achieved with the as-built surface quality, but with a polished surface and lower layer thickness, it could be doubled. Impact toughness and mechanical strength of the material are heavily dependent on the layer thickness, and while the best results were obtained with the lower layer thickness, the printing orientation can have a detrimental effect on it.
Additive manufacturing is an enticing way of producing complex geometries and optimized parts for special applications. Even though the achievable static properties for the printed material are usually good when compared to wrought materials, in many cases dynamic properties are known to be much worse. Often, the quality is sacrificed in respect of printing speed. Furthermore, printed materials have usually anisotropic behavior, caused by the remelting and fast cooling of each deposited layer. This means that the mechanical properties need to be measured in several directions in respect of the printing direction for attaining a more holistic approach to the achieved static and dynamic behavior. As a demonstration, this study focuses on determining the properties of 316L stainless steel-manufactured with laser powder bed fusion. A comprehensive set of samples for various testing methods were manufactured to investigate the effect of the layer thickness and printing orientation on the microstructure, mechanical properties, impact strength, and fatigue life. Fatigue performance of the material was evaluated in both axial and flexural bending comparing as-built and polished surface conditions. Bending fatigue testing revealed that a fatigue limit of 100 MPa at best can be achieved with the as-built surface quality, but with a polished surface and lower layer thickness, it could be doubled. Impact toughness and mechanical strength of the material are heavily dependent on the layer thickness, and while the best results were obtained with the lower layer thickness, the printing orientation can have a detrimental effect on it.
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