Fatigue crack nucleation and growth in laser powder bed fusion AlSi10Mg under as built and post-treated conditions

Publication type: 
Article
Author(s): 
Juan Guillermo Santos Macías, Chola Elangeswaran, Lv Zhao, Jean-Yves Buffière, Brecht Van Hooreweder, Aude Simar
Citation: 

Santos Macías, Elangeswaran, Zhao et al. (2021) Fatigue crack nucleation and growth in laser powder bed fusion AlSi10Mg under as built and post-treated conditions. Materials & Design 210 https://doi.org/10.1016/j.matdes.2021.110084

Description: 

Abstract : Numerous efforts have been devoted to produce reliable additive manufactured (AM) materials for structural applications. However, the critical fatigue issue poses a significant hurdle in relation to the nature of this production method. Despite the  relative flexibility of the laser powder bed fusion (LPBF) AM process, there exists a limitation in the possibility of tailoring parameters to obtain a satisfactory combination of porosity and surface roughness for adequate fatigue resistance. This quandary arises interest for posttreatments that could help overcome this limitation. Friction stir processing was proved to be a viable solution to improve fatigue behaviour of LPBF AlSi10Mg in the present work. Indeed, thanks to this post-process that reduces overall porosity and eliminates critical defects while keeping a satisfactory fine microstructure and static mechanical behaviour, fatigue resistance of the material was significantly enhanced. In contrast, the other studied post-process, stress relieve heat treatment, did not reduce porosity, which remained the main factor behind fatigue crack nucleation, cyclic life of the material being thus little affected with respect to the as built state. Furthermore, both post-treatments decreased fatigue crack growth rate by an order of magnitude. This is interpreted as being due to plasticity induced crack closure and crack branching.

Keywords : Laser powder bed fusion, Friction stir processing, Stress relieve heat treatment, AlSi10Mg, Total fatigue life, Fatigue crack growth.

Year of publication : 
2021
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Magazine published in: 
Materials & Design