False brinelling of needle roller bearings is actually a fretting corrosion of the surface since the rollers are the I. D. Of the bearing. Although its appearance is similar to that of brinelling, false brinelling is characterised by attrition of the steel, and the load on the bearing is less than that required to produce the resulting impression. It is the result of a combination of mechanical and chemical action that is not completely understood, and occurs when a small relative motion or vibration is accompanied by some loading, in the presence of oxygen.