Energy-Based Fatigue Assessment of Defect-Afflicted Cast Steel Components by Means of a Linear-Elastic Approach

Cast steel components are affected by manufacturing process-based imperfections, which severely limit their fatigue strength. In this work, the linear-elastic strain energy density concept is applied to assess the fatigue behaviour of bulk defect-afflicted components made of high-strength cast steel alloy G12MnMo7-4+QT. Based on analytical calculations, an energy-based design limit curve is derived which merges experimental results of notched and unnotched small-scale specimens into a statistically proven scatter band. The stress ratio dependency is also investigated. Moreover, a numerical methodology is introduced, which facilitates the energy-based fatigue assessment of complex spatial imperfections on the basis of radiographs. Validation of the established framework utilizing experimental results of defect-afflicted large-scale specimens leads to sound accordance of numerically and experimentally derived fatigue strength values, showing an average deviation of about only eight percent.

Automated summary

This study applies the linear-elastic strain energy density concept to evaluate the fatigue behavior of defect-afflicted cast steel components made of high-strength alloy G12MnMo7-4+QT. An energy-based design limit curve is derived through analytical calculations, which combines experimental results of notched and unnotched small-scale specimens. The stress ratio dependency is also investigated. Additionally, a numerical methodology is introduced for the energy-based fatigue assessment of complex spatial imperfections using radiographs. The established framework is validated through experimental results of defect-afflicted large-scale specimens, showing a close agreement between numerically and experimentally derived fatigue strength values with an average deviation of only eight percent.