Failure analysis of cracks at front flange R part of high-pressure compressor disc

To investigate the causes of cracks at the transition R part of the front stop web and the wheel rim of the high-pressure compressor disc of a certain engine, we used surface integrity detection, fracture analysis and other methods to analyze the cracks at the R part. The results showed that the cracks were fatigue cracks, and their formation was associated with multiple factors. The machining process caused significant wave patterns at the R part (with a peak-to-valley height difference reaching 31.64 μm), resulting in a local surface stress concentration factor (K_st) of 1.72. The damage to surface integrity became the main cause of fatigue crack generation. The shot peening reinforcement layer was significantly reduced by subsequent turning operations, and the previous shot peening strengthening process failed to completely eliminate the traces of the previous processing, resulting in a significant attenuation of the surface strengthening effect. Additionally, numerous micro-defects less than 20 μm generated in the surface further aggravated local stress concentration; the combined effect of these factors shortened the fatigue life of the compressor disc. Therefore, the following optimization strategies are proposed: improving the structure design of the R-groove to reduce the surface stress concentration, introducing advanced manufacturing technologies to enhance the surface quality, coordinating the shot peening and turning processes to retain the effective reinforcing layer, and strictly controlling storage and service environment to avoid damage to surface integrity. These measures can provide systematic technical support for preventing similar failures.