A New Method for the Evaluation of Wear Damage in Dry Rolling Contact by Sound Intensity Level and Residual Stress Measurements

The contact fatigue wear of rolling surfaces is associated with the behavior of dislocations located at the specimen surface and subsurface. This behavior depends on the Hertzian Pressure and specimen shear strength, which affect the residual stress fields developed during cyclic loading. This work describes a new nondestructive method to evaluate changes on the residual stress fields and wear damage in dry rolling contact. A disc-disc testing machine was used into a semi-anechoic chamber to evaluate the audible sound signal (noise intensity level) continuously generated by the mechanical contact. Pairs of discs of heat treated DIN 100Cr6 (AISI 52100) steel were tested under Hertzian nominal pressures from P sub o = 1.5 GPa to P sub o = 2.5 GPa, at velocities of 40 plus/minus 0.5 m/s. The sound signals were later distributed into box-and-plot graphics which indicated four percentile groups (quartiles) and revealed the main tendency and dispersion of these signals. An XRD analysis, using the sin exp 2 psi technique was applied to measure the residual stresses and to associate them with the noise intensity level quartiles at different stages of testing. Microstructural analyses of tested disc surfaces and resulting debris, using a Scanning Electron Microscope (SEM), showed a relation between the different noise levels and surface damage mechanisms, such as microspalling, micropitting, plastic deformation, delamination and brittle fracture.