The residual stresses on lubricated sliding surfaces during break-in and up to scuffing

In this paper, the residual stresses on a lubricated sliding surface and subsurface were measured during break-in and scuffing tests using the X-ray diffraction method. The cylinder-on-disk type tribometer was used with a line-contact geometry. Scuffing tests were carried out at constant load of 730 N. The break-in procedure was done at relatively low load compared to the amount of applied load in a scuffing test for 30 min. In the break-in procedure, the gradual formation and the distribution of compressive residual stresses near the surface prevented the surface from early failures caused by further sliding. During repeated sliding, the broken-in sliding surfaces represented relatively higher compressive residual stresses at the surface and subsurface than those that were not broken-in. During the process, when the compressive residual stresses at the surface were gradually increased to 300 MPa and the increase in the residual stresses at the subsurface diminished, surface failures were observed.