A comprehensive fracture analysis of a turbojet engine's compressor blade to prevent possible damage

This article offers an insightful examination of a turbojet engine (TJE) featuring an eight-stage axial compressor with a total of 808 blades. The fractured blade is expertly crafted from high-quality stainless steel 355. The composition of the blade is determined as 73.53–77.33% iron, 15–16% chromium, 4–5% nickel, 2.5–3.5% molybdenum, 0.5–1.25% manganese, 0.5% silicon, 0.10–0.15% carbon, 0.04% phosphorus, and 0.03% sulphur. The study thoughtfully analyses the fracture characteristics of 106 blades from the fourth stage of the compressor. A visual test and binocular stereo microscope (BSM) were employed to conduct the examination. While initial concerns about aeromechanical stress were raised, subsequent laboratory investigations illuminated pit and intergranular corrosion as significant factors. The corrosion was observed to have a diameter of approximately 0.005 inches and a depth of about 0.0015 inches. Notably, the findings indicate that the interplay between corrosion and high cyclic loads (HCLs) has contributed to increased blade fatigue. The fracture mechanism is mainly known as domestic object damage (DOD) or inner object damage (IOD). This study demonstrates that pitting and intergranular corrosion can nucleate minor cracks on the blades and lead to severe malfunction of turbojet engines unless the precautions offered in the last section of the article aren't taken.