Analysis on Cracking Reason of Deflector Roller of 9Cr2Mo Steel after Quenching and Tempering

The longitudinal cracking at the end of 9Cr2Mo steel deflector roller was analyzed by means of chemical composition analysis, macro and micro examination. The results showed that the main reasons included carbon and silicon content exceeded the standard limit of 9Cr2Mo steel, internal crack and the different size of original grain existed. At last improvement measures for the deflector roller is made based on the analysis results.