Investigation of microstructural influence on gear contact fatigue

To find materials that meet the future requirements of increasing load density in wind turbine gear structures, the commonly used reference material, 18CrNiMo7-6, and another high-strength steel are analyzed. Their fatigue properties are studied through twin disc rolling contact experiments and gear bending tests. This study aims to understand gear contact fatigue at the microscopic level, moving beyond the macroscopic focus that dominates current research literature. Detailed studies on microstructures, including grain structures, inclusions, and hardness, were conducted. To clearly establish the causal link between the varied fatigue performance observed in these materials, we propose a multiscale modeling workflow based on crystal plasticity as shown in Fig. 1. In this study, we focus on the impact of retained austenite (RA) and inclusions on fatigue performance. By employing representative elementary volume (REV) that are generated based on statistically representative crystallographic features and the measured characteristics of RA and inclusions, we assess their impact on fatigue resistance. Our research demonstrates that the rate of fatigue damage accumulation is influenced by both loading conditions and microstructural variations. Furthermore, we will discuss the effectiveness of the fatigue indicator parameter (FIP) in predicting fatigue performance.