Official Answer
Answer
Fatigue failure in wave springs starts at the point of maximum tensile stress, typically the inner diameter of a crest. Under Scanning Electron Microscopy (SEM), the presence of 'striations'—parallel lines marking each load cycle—confirms fatigue. If the striations are widely spaced, it indicates high-stress, low-cycle fatigue. If very fine, it is low-stress, high-cycle fatigue. In 17-7PH, failures are often accelerated by 'Alpha-prime' martensite embrittlement if the heat treatment was improper, which would be visible as a more granular fracture surface near the initiation site.
