Mechanical damage to the bearing seat refers to the appearance of varying degrees of grooves on the alloy surface of the bearing, and in severe cases, metal peeling and large areas of messy scratches on the contact surface; In general, both contact surface damage and ablation occur simultaneously. The main reason for mechanical damage to bearings is that the surface of the bearing is difficult to form an oil film or the oil film is severely damaged.

（2）軸承穴蝕

(2) Bearing pitting

軸承座在氣缸壓力沖擊載荷的反復作用下，表面層發(fā)生塑性變形和冷作硬化，局部喪失變形能力，逐步形成紋并不斷擴展，然后隨著磨屑的脫落，在受載表面層形成穴。一般軸瓦發(fā)生穴蝕時，是先出現(xiàn)凹坑，然后這種凹坑逐步擴大并引起合金層界面的開裂，裂紋沿著界面的平行方向擴展，直到剝落為止。Tr軸承座穴蝕的主要原因是，由于油槽和油孔等結構要素的橫斷面突然改變引起油流強烈紊亂，在油流紊亂的真空區(qū)形成氣泡，隨后由于壓力升高，氣泡潰滅而產(chǎn)生穴蝕。穴蝕一般發(fā)生在軸承的高載區(qū)，如曲軸主軸承的下軸瓦上。

Under the repeated action of cylinder pressure impact load, the bearing seat undergoes plastic deformation and cold work hardening on the surface layer, losing local deformation ability, gradually forming wrinkles and continuously expanding, and then forming cavities on the loaded surface layer as the debris falls off. When the bearing shell undergoes pitting corrosion, pits first appear, and then these pits gradually expand and cause cracking at the alloy layer interface. The cracks propagate parallel to the interface until they peel off. The main reason for the pitting corrosion of Tr bearing seats is that the sudden change in the cross-section of structural elements such as oil grooves and oil holes causes strong turbulence in the oil flow, forming bubbles in the vacuum zone where the oil flow is disrupted. Subsequently, due to the increase in pressure, the bubbles collapse and pitting corrosion occurs. Cavitation usually occurs in the high load area of bearings, such as the lower bearing shell of the crankshaft main bearing.

（3）疲勞點蝕

(3) Fatigue pitting

軸承疲勞點蝕是指，由于發(fā)動機超負荷工作，使得軸承工作過熱及軸承間隙過大，造成軸承中部疲勞損傷疲勞點蝕或者疲勞脫落。這種損傷大多是因為超載軸承間隙過大，或者潤滑油不清潔內中混有異物所致。因此，使用時應該注意避免軸承超載工作不要以過低或過高的轉速運轉；怠速時要將發(fā)動機調整到穩(wěn)定狀態(tài)；確保正常的軸承間隙，防止發(fā)動機轉速過高或過低；檢查調整冷卻系統(tǒng)的工作情況，確保發(fā)動機的工作溫度適宜。

Bearing fatigue pitting refers to the phenomenon where the engine operates under overload, causing overheating and excessive bearing clearance, resulting in fatigue damage, pitting, or fatigue detachment in the middle of the bearing. This kind of damage is mostly caused by excessive clearance between overloaded bearings or impurities mixed in the lubricating oil due to unclean lubrication. Therefore, when using, attention should be paid to avoiding bearing overload and not operating at low or high speeds; When idling, adjust the engine to a stable state; Ensure normal bearing clearance to prevent engine speed from being too high or too low; Check and adjust the operation of the cooling system to ensure that the engine's operating temperature is appropriate.

（4）軸承合金腐蝕

(4) Corrosion of bearing alloy

軸承合金腐蝕一般是區(qū)為潤滑油不純，潤滑油中所臺的化學雜質（酸性氧化物等）使軸承合金氧化而生成酸性物質，引起軸承合金部分脫落，形成無規(guī)則的微小裂孔或小凹坑。軸承合金腐蝕的主要原因是潤滑油選用不當軸承材料耐腐蝕性差，或者發(fā)動機工作粗暴溫度過高等。

Corrosion of bearing alloys is generally caused by impure lubricating oil, and chemical impurities (such as acidic oxides) in the lubricating oil oxidize the bearing alloy to form acidic substances, causing partial detachment of the bearing alloy and the formation of irregular small cracks or pits. The main reason for corrosion of bearing alloys is improper selection of lubricating oil, poor corrosion resistance of bearing materials, or rough engine operation with high temperatures.

（5）軸承燒熔

(5) Bearing melting

軸頸和軸承摩擦副之間有微小的凸起金屬面直接接觸，形成局部高溫，在潤滑不足冷卻不良的情況下，使軸承合金發(fā)黑或局部燒熔。此故障常為軸頸與軸承配合過緊所致；潤滑油壓力不足也容易使軸承燒毀。

There are small raised metal surfaces in direct contact between the journal and the bearing friction pair, forming local high temperatures. In the case of insufficient lubrication and poor cooling, the bearing alloy may become black or locally melt. This fault is often caused by the tight fit between the shaft neck and the bearing; Insufficient lubricating oil pressure can also easily cause bearing burnout.

（6）軸承走外圓

(6) Bearing outer circle

軸承走外圓就是軸承在座孔內有相對轉動。軸承走外圓后，不僅影響軸承的散熱，容易使軸承內表面合金燒蝕，而且還會使軸承背面損傷，嚴重時燒毀軸承。其主要原因是，軸承過短凸榫損傷加工或者安裝不符合規(guī)范等。

The outer circle of the bearing refers to the relative rotation of the bearing within the seat hole. After the bearing passes through the outer circle, it not only affects the heat dissipation of the bearing, which is easy to cause alloy erosion on the inner surface of the bearing, but also damages the back of the bearing, and in severe cases, burns out the bearing. The main reason is that the bearing is too short and the tenon is damaged during processing or installation, which does not comply with the specifications.

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