The authors examined the problems of formation and cumulation of fatigue damage in alternating uniaxial and biaxial stress states (circular bending, combined circular bending, and static torsion at τ/σ = 0 and 1). It is shown that the individual stages of the failure process can be determined by direct measurements of the magnetic permeability of the tested component in periodic loading. A special fatigue machine and an FK-1 ferroprobe controller of damage were constructed for these tests. For statistical evaluation of the parameters of the failure periods, the authors selected a linear correlation between the logarithms of endurances and stresses. Line of equal damage with a confidence range were obtained. The significance of the sampling coefficient of correlation and the parameters of the damaged lines was confirmed. To determine the effect of tangential stresses on the duration of the failure periods, the authors propose an endurance coefficient for which an expression has a function of the level of overstresses and nonfailure probability was derived. The problem was solved in a computer.