D3.1 Advanced fatigue testing methods for high-strength steels

Steel4Fatigue project aims to investigate fatigue-optimised solutions for dynamic components in the automotive industry. It will achieve this by introducing new materials and technologies to reduce the weight of trucks and cars by 10%. These solutions will be based on specially developed materials with high fatigue performance (AHSS and spring steels), advanced computer modelling for accurate fatigue prediction, and innovative experimental methodologies to reduce testing time. The project will also focus on minimising environmental impact evaluated through life cycle assessment, reducing energy consumption and material usage through improved steelmaking processes, and enhancing fatigue performance to facilitate wider market adoption of Steel4Fatigue solutions. Attention will be given to steelmaking, including internal defects and scrap quality, as well as manufacturing processes like cold forming and mechanical shearing to better understand their impact on the fatigue performance of cyclic-loaded components. To achieve these goals, the project will develop methods for evaluating these effects and improving the fatigue design of selected demonstrators. It will also explore microstructures for optimal fatigue performance. Two industrial demonstrators will be defined to validate the proposed solutions. The project's contributions include reducing lead times to market through advanced fatigue testing methodologies and models. The outcomes will provide materials, modelling, and experimental tools for designing fatigue-resistant parts across multiple sectors. Practical guidelines will be established for factors such as proposed microstructures, advanced testing, modelling approaches, and the influence of manufacturing and steelmaking processes on part performance. 

The present deliverable provides a comprehensive overview of the experimental approaches developed for fatigue evaluation in the Steel4Fatigue project. 

The document describes in detail the rapid methods created for evaluating the fatigue performance of the selected materials, including thick first-generation AHSS and spring steels. The methods presented in this deliverable are the Stiffness Method and the Self-Heating Method. Additionally, a new approach relating fatigue performance to the fracture toughness of the materials is proposed to support the selection of the appropriate material based on its fatigue notch sensitivity.