Causes of locking hole cracking of cast wind power spindle locking hole

The locking hole of a QT500-14 casting spindle cracked after cutting. The reasons for the cracking of the locking hole were analyzed by means of macroscopic observation, chemical composition analysis, scanning electron microscope analysis, metallographic examination and mechanical property test. The results show that there was an obvious graphite dense distribution area near the cutting surface.Under the action of organizational stress and thermal stress introduced during the cutting process, micro-cracks were generated in this area. The cracks continued to extend under the action of residual stress, which eventually led to the cracking of the spindle locking hole.