White Etching Cracks in Bearing
Bearings that are used in large industrial gearboxes, train applications, paper mills, crusher mill gearboxes and lifting gear drives are subjected to a wide variety of operating conditions that can push them beyond their limits. Such conditions can result in bearing failure, often called white etching cracks or white structure flaking. What are white etching flakes? White etching cracks are cracks within a bearing. White etching area refers to the white appearance of the altered microstructure of a polished steel sample. The affected areas usually contain ultra-fine, nano-recrystallised, carbide-free ferrite with carbide particles. These areas appear white under the optical microscope due to their low-etching response to the etchant. White etching areas are usually 10-50% harder than the surrounding unaffected microstructure. What causes white etching cracks to develop? Two physical parameters accelerate rolling contact fatigue. Stresses higher than anticipated - Str...