Micro-Defects-Related Low Cycle Fatigue Mechanical Model of the Nuclear-Grade S30408 Stainless Steel

Area of Science:

• Materials Science
• Mechanical Engineering
• Nuclear Engineering

Background:

• Nuclear reactor components require materials with high fatigue resistance.
• Understanding low cycle fatigue behavior in stainless steels is crucial for operational safety.

Purpose of the Study:

• To investigate the low cycle fatigue behavior of nuclear-grade S30408 stainless steel.
• To establish a quantitative model for predicting fatigue life based on microstructural defects and hardness.
• To assess the accuracy of traditional fatigue life prediction formulas.

Main Methods:

• Performed continuous and interrupted low cycle fatigue tests at room temperature.
• Conducted Vickers hardness testing and microstructure characterization.
• Utilized the Basquin formula for fatigue life prediction.
• Developed a quantitative mechanical model linking KAM (Kernel Average Misorientation) and Vickers hardness (Hv).

Main Results:

• Characterized microstructural defect evolution under cyclic loading.
• Established a predictive model for Vickers hardness with >90% accuracy.
• Demonstrated the model's utility in assessing fatigue damage in S30408 stainless steel.

Conclusions:

• The developed quantitative model provides accurate predictions of Vickers hardness during low cycle fatigue.
• This research offers significant insights for fatigue life prediction in 304 stainless steels within nuclear systems.
• The findings contribute to ensuring the safe operation of nuclear reactors.