Experimental Study on Fatigue Behavior of 35CrMo Steel after Torsional Prestrain

Low cycle and high cycle fatigue tests of 35CrMo steel at different pretorsional angles were conducted and cyclic hardening and softening curves, hysteresis loops and S-N curves were obtained of 35CrMo steel after the torsional prestrain. Scanning electron microscopy (SEM) analysis was also made of the fatigue fracture. The results show that: 35CrMo steel features obvious cyclic softening with basically the same law and degree at different torsional prestrains. The area surrounded by the stress-strain hysteresis loop decreases with the increment of the pretorsional angle; the torsional prestain reduces the fatigue life of the materials.