In power generation and other high-temperature industrial sectors, long-term service of materials faces severe challenges from high-temperature creep deformation. High-temperature materials such as HR3C steel are prone to creep voids and microcracks at grain boundaries during long-term operation, eventually leading to material failure and seriously threatening industrial safety. Therefore, an in-depth understanding of creep damage mechanisms, especially the nucleation and growth processes of creep voids and microcracks, is crucial for accurately predicting component life and developing more advanced and durable materials.
Methods
Materials: HR3C austenitic steel.
X-ray Computed Tomography (CT): High-resolution 3D imaging to visualize the distribution and interconnection of creep voids and microcracks.
Three-dimensional Atom Probe (3DAP): Nanoscale analysis to study the elemental composition of grain boundaries and interfaces, and the role of solute elements in promoting creep damage.
Highlights
Creep Void Evolution: The volume fraction of creep voids increases with increasing creep time, driven by the growth and coalescence of individual voids.
Microcrack Morphology: Irregular layered or "W"-shaped microcracks were observed along grain boundaries. The number and size of microcracks decrease with decreasing stress levels.
Element Segregation: P and Si elements were found to be enriched at the M₂₃C₆/γ interface, which promotes the nucleation of creep voids and microcracks under stress.
Stress Influence: Stress has a significant influence on the distribution of creep voids and the propagation path of microcracks. Lower stress levels tend to promote intergranular creep damage, while higher stress levels can lead to transgranular cracking.
Fig. 2. Microstructures of cross-sections and longitudinal sections under different stresses
Editor's Note
Three-dimensional investigation of creep cavitation is crucial for a deeper understanding of creep failure. This is a valuable and meaningful research direction. We look forward to more scholars conducting relevant research to jointly promote progress in this field.
Welcome to the International Center for Creep Prediction ICCP! We share the latest research and insights on high-temperature materials, strength, Creep, and Fundamental Theory and experiments of Materials. We welcome you to share your research for free! Join us in advancing the field!
