Analysis on Fracture Reason of Motor Shaft

The fracture reason of motor shaft was analyzed by means of macro examination, chemical composition analysis, mechanical property testing, metallographic examination, fracture analysis and so on. The results showed that the immediate cause of fracture was stress concentration from silicate inclusions on shaft side, which resulted in original crack initiation; its remote cause was high concentration of nonmetallic inclusions, undersurface pinhole, surface crack, brittle material and low impact energy of the material.