The effect of carbon element content on the fatigue properties of steel forgings

Fatigue tests were conducted on steel forgings with different carbon element contents to investigate the effect of carbon element content on the fatigue performance of steel forgings, and to analyze their fracture and strengthening mechanisms. The results show that as the carbon content increased, the fatigue strength of materials gradually increased. At the same strain level, the sample with a carbon element mass fraction of 0.3% had the longest fatigue life. Microcracks originated from geometric defects or non-metallic inclusions on the surface of the specimen, and propagated smoothly in the strip-shaped area. The specimen eventually fractured rapidly in rapid shear. After high-temperature tempering, almost all supersaturated carbon elements in the material precipitated in the form of carbides, which improved its fatigue performance in the form of solid solution strengthening.