Cause Analysis on Crack Formation of Bearing Roller of Railway Axle Box

Macrocracks were found in bearing roller of one railway axle box during the overhaul work. The crack formation cause of the bearing rolling was analyzed by macrographic inspection, chemical compositions analysis, hardness test and micrographic inspection. The results show that grinding burn exsited in the crack area of bearing roller, which led to the stress concentration in this area. Due to the combined action of mechanical stress and residual stress, cracks generated and extended in the grinding burn area, and finally propagated into macrocracks.