Effect of Structural Anisotropy on a Fracture Mode of Ferromagnetic Steels Under Cyclic Loading

The potentials of nondestructive test methods are experimentally substantiated to get a cyclic loading fracture mode of ferromagnetic steels against their structural anisotropy, determined by coercive force measurements. Elastic static or cyclic loading was revealed to be consistent with a stable structure with certain anisotropy kinetics due to applied stresses. After plastic deformation, a new stable structure is formed induced by residual stresses. The anisotropy factor depended on the level of active relative stresses under elastic and elastoplastic, static, or cyclic loading. The change in kinetics direction for the anisotropy factor with elastic or elastoplastic loading defines the safe range of mechanical loading caused by reversible damage processes, as well as the ranges of accumulation risks for irreversible fatigue, high- and low-cycle fatigue and quasistatic damages giving rise to corresponding fracture modes. The nondestructive coercimetric method permits setting the metal endurance, yield limit, and transition stress from low-cycle fatigue to low-cycle quasistatic fracture.