Failure mechanism of the inner ring raceway in the backing bearing for multi-roll rolling mills

Backing bearings are crucial components of multi-roll rolling mills, and their failure mechanisms are diverse due to the complex service loads. The failure mechanism of the inner ring raceway in the backing bearing was investigated. The wear surface of the inner ring raceway presented typical abrasive wear morphology. The central wear region experiences more severe wear, with larger wear pits, while the wear in the edge regions is lighter, and the wear pits are smaller. The inclusion type and size analysis indicated that the size and distribution of inclusions meet the standard requirements. The gradient hardness distribution of the raceway surface can enhance the fatigue resistance of the inner ring. It has been confirmed that the damage to the inner ring is caused by abrasive wear rather than rolling contact fatigue. The failure mechanism of the inner raceway was proposed. First, the impact process causes hard contact between the rollers and the raceway surface, which results in the generation of abrasive particles. Then, three-body wear between the rollers and the raceway occurred after the abrasive particles enter the lubricating oil. Due to the higher stress in the center and lower stress on the edge on the inner raceway, continuous abrasive wear has led to the formation of a central wear region and edge regions. • The failure mechanism of the inner raceway surface of the backing bearing is revealed to be abrasive wear • Characterizing the morphological features of two wear regions • Measuring mechanical properties of gradient material bearing steel through experiments • Analyzing the competitive influence of hardness gradient in the carbonized layer on fatigue and impact toughness