Strength changes of 40 Cr steel subjected to cyclic torsion below the fatigue limit

Abstract This paper investigates the fatigue and static strength variation of 40 Cr steel which has been subjected to cyclic torsion below the fatigue limit. The experimental results show that an improvement in fatigue strength can be exhibited if low-amplitude cyclic torsion and loading cycles are properly selected. The static strength can also be strengthened through the improvement of fatigue strength. It should be added that there is no significant static strength change in the first 50 % of the fatigue damaging process.