High Cycle Fatigue in the Hierarchical Microstructure of 316L Stainless Steel Manufactured by Laser Powder Bed Fusion

von Xuemei Lyu

191 Seiten, Taschenbuch

Kurzbeschreibung des Verlags

Design concepts of components produced by additive manufacturing require an in-depth understanding of the relations between the process parameters, microstructure, and mechanical properties. Laser Powder Bed Fusion (PBF-LB/M) 316L stainless steel (SS) was deeply studied and reported to achieve comparable or better static and dynamic performances than its counterparts manufactured by conventional casting and forging. PBF-LB/M 316L SS possesses a hierarchical microstructure consisting of melt pools, lack of fusion (LoF) defects, and grains that contain fine cellular structure. Understanding the fatigue mechanism and the effect of the hierarchical microstructure on the fatigue strength is critical for its applications under cyclic loading.
In this thesis, PBF-LB/M 316L SS was produced with a preheated platform (200°C and 400°C). Quasi-in-situ bending tests in the HCF regime and micropillar compression tests were performed to investigate the effects of local microstructural heterogeneity on the mechanical properties and the deformation mechanism. Statistically equivalent representative volume elements (SERVEs) were generated according to the microstructural characteristics. The traditional incremental analysis method for polycrystalline alloys is computationally expensive. Therefore, direct cyclic analysis (DCA) combined with a phenomenological crystal plasticity (CP) model was used to predict the stable cyclic responses and the fatigue limit of the SERVEs, resulting in a much lower computational cost. The multiscale modelling benefits a deep understanding of the complicated effects of the defects, grains, and various CRSS from different dislocation cells on the fatigue limit and the scatter. The tests and simulations facilitate the microstructural based material design.

• Reihe: Werkstoffanwendungen im Maschinenbau
• ISBN: 9783819103353
• Sprache: Englisch
• Erscheinungsdatum: 05.12.2025
• Genre: Technik/Maschinenbau, Fertigungstechnik
• Verlag: Shaker