What are small hairline cracks across the leading edge of a turbine blade called?

The small hairline cracks observed across the leading edge of a turbine blade are known as stress rupture cracks. This type of cracking typically occurs due to high-stress levels combined with prolonged exposure to elevated temperatures. As the turbine blades operate, they experience significant centrifugal forces and thermal stress, which can lead to the development of these cracks over time. Stress rupture cracks generally arise from a combination of material fatigue and the dynamic loading conditions that the blades undergo during their operational life.

This terminology emphasizes the unique characteristics of the cracking as it relates to the enduring stress that blades must withstand, especially in high-performance applications. Understanding this concept is crucial for maintenance and safety assessments of turbine engines, as monitoring for these cracks can help prevent catastrophic failures. In contrast, while other options describe different phenomena related to material failure, they do not specifically capture the nature and causes of the small hairline cracks on turbine blades.