Identification and Modeling of Fatigue Damage Mechanisms in Al-Si-Mg Cast Alloys under Fatigue Loading at High and Very High Number of Cycles

• Applicants: Professor Dr.-Ing. Ulrich Krupp; Professor Dr.-Ing. Frank Walther
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: from 2015 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 282318703

Within the second project phase (pp2), the relationship between microstructural characteristics and fatigue properties will be investigated by means of combined EBSD and EDX mappings as well as TEM examinations (post-mortem) at the microstructural level by in situ tensile, bending and fatigue tests. The scientific findings will be correlated with the characteristic profiles of the response variables of the successfully implemented new measurement methods (high-resolution thermography, alternating current potential drop technique, far-field microscopy) as well as high-resolution digital image correlations (new in pp2) in order to understand the correlation between mechanisms and response variables. The relationship of the response variables with fatigue-induced changes in microstructure as a function of the dominant mechanisms will be described in a model-based manner and used to optimize the measurement and test methods. The 2D microstructures will also be used to generate synthetic, representative microstructures of the alloy and microstructure variants for boundary-element-based modeling of short and long crack propagation behavior. Based on the experimental and modeling results, the relationships between microstructure and fatigue properties will be described and implemented in numerical casting and phase simulations. Subsequently, the transferability of the developed process-microstructure-property relationships to complex component-like structures (chassis components, rocker arms) will be investigated with the goal of a fatigue-resistant material design. The focus is placed to a reliable prediction of the fatigue life at high and very high cycles for Al-Si-Mg alloys, which are solidified and heat-treated under freely selectable conditions.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr.-Ing. Wilhelm Michels