Publications

Processing Optimization of the New Steel Grade 45SiCrV9Ni for Modern Leaf Springs in Battery Electric Vehicles

Journal: MDPI Engineering Proceedings

Authors: Niki Nouri, Borja Escauriaza, Christos Gakias, Georgios Savaidis, Roberto Elvira, Stefan Dietrich, Volker Schulze

The optimization of battery electric vehicles requires advanced high-strength steels that combine ductility and toughness, enabling lightweight leaf spring constructions with improved performance. This study investigates processing optimization by comparing the newly developed 45SiCrV9Ni, previously identified as promising for stress peening and fatigue, with the conventional 51CrV4 as a benchmark. Dilatometric, mechanical, and microstructural analyses were conducted in as-supplied and heat-treated conditions. Both steels show excellent high-temperature ductility, making them suitable for hot forming under similar conditions. However, 45SiCrV9Ni requires a higher temperature for homogenized austenitization. After tempering, it consistently exhibits superior hardness and toughness compared to 51CrV4. Importantly, its ductility remains nearly constant over a wide tempering temperature range, allowing lower ones to be chosen without compromising strength or toughness, offering additional energy-saving possibilities. These results highlight the potential of 45SiCrV9Ni for leaf spring applications.

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A High-Accuracy 3D Simulation of Surface Shot Peening

Journal: MDPI Engineering Proceedings

Authors: Christos Gakias, Efstratios Giannakis, Paschalis Adamidis, Stefan Dietrich, Volker Schulze, Georgios Savaidis

Shot peening is a widely used surface treatment method for improving fatigue life by inducing surface compressive residual stresses. In critical automotive components such as parabolic leaf springs, shot peening under pre-tension (stress shot peening) can further enhance durability. This study presents a finite element model simulating stress peening in high-strength spring steels, incorporating realistic boundary conditions, material degradation due to decarburization, and stochastic shot properties, offering a high-accuracy yet computationally efficient alternative to extensive experimental testing. Results show that both below- and above-yield pre-stressing produce beneficial residual stresses, while the consideration on decarburization effects significantly alters surface stress fields. The model offers a reliable, time-efficient alternative to experiments for process and fatigue life optimization.

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