A fast evaluation method for fatigue strength of maraging steel: The minimum strength principle

摘要

The relationship between fatigue strength and tensile properties has drawn widespread concern in recent decades. It is gradually recognized that the fatigue strength is dependent on the strength of the weakest zone in materials, while the regular tensile test could only obtain the global strength. The present study, for the first time, constructed a fast evaluation method, in which extremely slender specimens were employed. It is found that, when the specimen is slender enough, i.e., the soft oriented grain could occupy the whole section of the specimen, the strength of the soft domain could be related to the fatigue strength. In the 18Ni maraging steels, the fatigue crack would nucleate in the precipitate free zone (PFZ), which is the soft domain. Furthermore, the fatigue strength of fully reversed loading test nearly equals to the yield strength of the PFZ measured by the slender tensile test. This founding may shed light on the fast evaluation of fatigue strength, which could bring great economic benefits and save invaluable time.