Effect of contact pressure on torsional fretting fatigue damage of 316L austenitic stainless steel

Fretting is the small amplitude relative oscillatory motion between two solid contact surfaces. Many factors would make impacts on the fretting process, the body stress and contact pressure can be regarded as two major independent factors resulting in the fretting fatigue. The effects of torque and contact pressure on torsional fretting behavior of 316 L austenitic stainless steel are studied in a cylinder-on-cylinder contact configuration. The results indicate that torsional fatigue life drops rapidly due to fretting. The S-N curves of torsional fretting fatigue show a shape of “C”. Along with increasing the contact pressures, the fretting fatigue life decreases and enters to a platform area. The variety law of friction coefficient under different contact pressures is obtained. Both fatigue fracture and fretting scar are analyzed with SEM, EDX, XPS and three-dimensional white light interferometer (3D). The study shows that the torsional fretting fatigue is influenced by fretting running behavior. Meanwhile, the depth of crack initiation position would also be affected by contact pressure. In this paper, we proposed the failure mechanisms of the fretting zone, including plastic deformation, delamination, plow and oxidative wear.