Creep fatigue interaction at high temperature in C630R ferritic/martensitic heat-resistant steel

• DOI: 10.1016/j.jmrt.2024.08.193
• Publication Date: 2024-08-30T05:14:18Z
• Authors: Kailun Ding; Zhengxin Tang; Xikou He; Xitao Wang; Jinshan He; Jiajia Qiu
• Keywords: Hold time; Mining engineering. Metallurgy; Microstructural evolution; Creep-fatigue; TN1-997; Fracture mechanism; 02 engineering and technology; C630R heat-resistant steel; 0210 nano-technology; Softening behavior

The study investigated the creep-fatigue interaction behavior, fracture mechanism, and microstructure evolution of C630R ferritic/martensitic heat-resistant steel at 630 °C 1% strain amplitude. results indicate that exhibits noticeable cyclic softening with a decrease in ratio from 0.46 to 0.40 as loading time increases. Microstructure was examined using optical scanning electron microscopes, revealing appearance secondary cracks on longitudinal section sample. These exhibited curved expansion trend multiple deformations highly bifurcated micro-cracks low 30s. However, when load holding increased 300s, fatigue tended expand straight line fewer branches. Furthermore, observed crack growth path under different times showed enrichment Fe Cr, tip containing Cr oxide, which helped prevent propagation. As increases, rise closure resulting oxidation leads Electron backscatter diffraction observation revealed formation numerous substructures recrystallized grains after varying times, enhancing material's resistance Moreover, found increasing dwell time, deformed decreased, substructural became dominant (57.68% 62.77% 30s respectively). This resulted shorter prolonged retention, length decreasing 146.36 μm 109.09 300s time. Additionally, kernel misorientation angle value decreased significantly leading higher likelihood or holes forming regions high KAM values, where low-angle grain boundaries were formed.