Corrosion damage to rolling bearings is generally due to the phenomenon of corrosion (rusting) caused by moisture: brown discoloration over the entire FAG bearing surface, usually in the form of unevenly distributed small pits, Figure 53. In many cases, there are many rust spots distributed at the spacing of the rolling elements (static corrosion). When the bearing is stationary for a long time, the capillary phenomenon can cause the moisture to collect in the contact area, see Figure 54. This will lead to subsequent wear and early failure at rust spots. Causes: Improper storage in warehouses (relative air humidity> 60 %) Severe temperature changes (condensation of moisture) Seal failure (accelerated by abrasive action of dust, Fig. 87) Unsuitable lubricant Remedy: According to rolling bearing manufacturer Proper storage according to the instructions Improve sealing (add extra protection where possible) Use lubricants with anti-corrosion agents Relubricate bearings with grease frequently, especially before long downtimes 53: Rusted FAG deep grooves Ball bearing outer ring whose rust protection is destroyed by moisture. Corrosion indentations distributed at the distance between the rolling elements on the raceway Corrosion phenomena due to intrusion of the medium: usually black corrosion indentations, see Figure 55. Causes: Improper storage in warehouses (aggressive chemicals stored in the same place) Seal failures Unsuitable lubricants Store according to the rolling bearing manufacturer's instructions Improve seals Use lubricants with anti-rust properties 55: Due to intrusion Surface damage caused by sexual media. Corrosion pits are often black.