Bearings Alloy Corrosion
Chemical impurities in lubricants, such as acidic oxides, cause bearing alloys to oxidize and produce acidic substances. Corrosion of bearing alloys is typically due to impure lubricants. This can lead to the detachment of bearing alloys, forming irregular fine cracks or pits. The main reasons for bearing alloy corrosion are incorrect lubricant selection, poor corrosion resistance of the bearing material, and possibly inefficient engine operation and excessive temperatures.

2. Mechanical Damage
In severe cases, metal flaking may occur on the contact surface, resulting in extensive and chaotic scratch marks; typically, mechanical bearing damage refers to varying degrees of grooves on the alloy surface of the bearing liner. The primary reasons for surface damage and ablation are the difficulty in forming or the severe damage of the oil film on the bearing surface due to mechanical wear of the bearing.
3. Bearing Cavitation
The surface undergoes plastic deformation and cold working hardening, with the sliding bearing subjected to repeated impacts from cylinder pressure loads. Some deformation capacity is lost, gradually forming lines that expand over time, and then cavities are formed on the load surface as the debris falls. Generally, when the bearing shell shows pitting, it first appears as pinpoint marks, which then gradually enlarge, causing the alloy layer interface to crack. The cracks expand parallel to the interface until they stop descending. The main cause of cavitation in sliding bearings is the sudden change in cross-section of layout elements such as oil grooves and oil holes, leading to severe oil flow imbalance. Unbalanced oil flow creates vacuum zones that form bubbles, which then lead to cavitation due to increased pressure and bubble rupture. Cavitation typically occurs in high-load areas of the bearing, such as the lower bearing of the crankshaft main bearing.
4. Bearing Melting
A small protruding metal surface exists directly between the shaft neck and the bearing conflict surface of the component. In the absence of smoothness and inadequate cooling, the bearing alloy may become blackened or partially melted. This issue is typically caused by the shaft neck and bearing fitting too tightly together; insufficient stable oil pressure can only lead to the bearing being burned out.