Study on Cyclic Loading Characteristics of EH500 High-Strength Steel for Heavy Icebreakers

Abstract Heavy icebreakers are specifically designed to operate continuously in polar regions. During navigation, the hull structure withstands repeated loading and unloading effects caused by continuous collisions with sea ice. To better understand the performance of the EH500 high-strength steel, which is widely used in heavy icebreakers, experimental tests were performed under cyclic loads with varying amplitudes to simulate demanding conditions. The outcome reveals that EH500 steel exhibits a remarkable cyclic softening feature, with a stress difference of up to 300 MPa between its maximum and minimum yield strengths throughout the entire cyclic process. However, the differences between tensile and compressive yield strengths remain minimal across cycles, indicating that the Bauschinger effect is negligible. Additionally, as the amplitude of cyclic loading increases, the fatigue life of EH500 steel decreases following a power–law relationship. This research provides a foundation for improving the structural safety design of heavy icebreakers operating in extreme ice environments.