This paper uses a two-scale material modeling approach to investigate fatigue crack initiation and propagation of the material X10CrMoVNb9-1 (P91) under cyclic loading at room temperature. The Voronoi tessellation method was implemented to generate an artificial microstructure model at the microstructure level, and then, the finite element (FE) method was applied to identify different stress distributions. The stress distributions for multiple artificial microstructures was analyzed by using the physically based Tanaka–Mura model to estimate the number of cycles for crack initiation. Considering the prediction of macro-scale and long-term crack formation, the Paris law was utilized in this research. Experimental work on fatigue life with this material was performed, and good agreement was found with the results obtained in FE modeling. The number of cycles for fatigue crack propagation attains up to a maximum of 40% of the final fatigue lifetime with a typical value of 15% in many cases. This physically based two-scale technique significantly advances fatigue research, particularly in power plants, and paves the way for rapid and low-cost virtual material analysis and fatigue resistance analysis in the context of environmental fatigue applications.

This study investigates the fatigue life of AlSi10Mg alloy produced by laser powder bed fusion (LPBF) using experimental and multiscale modeling methods. A micromodel developed based on EBSD and SEM data simulates fatigue microcrack nucleation with the Tanaka–Mura model and FEM. The effects of the alloys heterogeneous microstructure, including SiC particles, on fatigue crack initiation are examined. Micropillar tests and high‐resolution SEM analyses study slip system behavior and plastic deformation. Long crack propagation is analyzed using the NASGRO equation, with total cycles till failure calculated for each stress amplitude. The fatigue life results, represented in an curve, show good agreement between computational and experimental data. Microscopic and macroscopic features like second phases, grain sizes, orientations, and macropores significantly influence the fatigue life of LPBF materials.

In this study, the fatigue life of AlSi10Mg alloy produced by the laser powder bed fusion (LPBF) method is investigated through an extensive experimental and methodological approach. Electron backscatter diffraction (EBSD) and scanning electron microscope (SEM) analyses were conducted to examine the microstructural features of the material. Micropillar tests were performed to assess the deformation and slip movement of dislocation systems, as well as to evaluate the critical resolved shear stress (CRSS), which is a crucial parameter influencing the deformation and fatigue performance of metallic materials. The experimental findings provide essential insights into the microstructural characteristics and mechanical behaviour of AlSi10Mg, forming a robust foundation for subsequent computational studies. Finally, the methodology of the physically-based modelling approach is explained together with the experimental data extraction to develop such a modelling approach. The more thorough explanation and implementation of the physically-based modelling approach will be brought in part B.

This study presents a comprehensive multi-scale simulation approach to investigate the fatigue behaviour of AlSi10Mg alloy produced by the laser powder bed fusion (LPBF) method. Fatigue crack initiation within the microstructure is modelled using the physically-based Tanaka-Mura equation, developed from electron backscatter diffraction (EBSD) and scanning electron microscope (SEM) data. The fatigue crack growth is analyzed using the NASGRO equation, allowing for a detailed simulation of both crack initiation and propagation. The total number of cycles for each stress amplitude is calculated by summing the cycles required for micro-crack initiation and long-crack propagation, resulting in the generation of fatigue life (S-N) curves. This simulation approach provides a thorough understanding of the material’s behaviour under cyclic loading, leveraging the microstructural insights obtained from experimental data.