Pinnaväsymyskuluminen

Pinnaväsymyskuluminen, often referred to as fretting corrosion in English, is a form of surface degradation that occurs when two surfaces in contact experience small, oscillatory movements relative to each other. This movement, even if seemingly insignificant, can lead to the abrasion and subsequent corrosion of the surfaces. The process typically involves the mechanical removal of protective oxide layers, exposing fresh metal to the surrounding environment.

The damage is characterized by pits, grooves, or a general roughening of the contacting surfaces. The severity of fretting corrosion depends on several factors, including the amplitude and frequency of the relative motion, the applied load, the materials in contact, and the presence of corrosive agents like moisture or chemicals in the environment. Metals that form brittle oxide layers are particularly susceptible.

Fretting corrosion can significantly reduce the fatigue life of components. It is commonly observed in bolted or riveted joints, splines, gears, and any mechanical connection subjected to vibration or slight relative motion under load. The formation of wear debris, often appearing as a fine powder or paste, is a hallmark of fretting. This debris can further accelerate the degradation process by acting as an abrasive medium. Mitigation strategies often involve reducing vibration, increasing lubrication, using more resistant materials, or designing for tighter fits to minimize relative movement.