A Metallurgical failure analysis was performed after a large grass mower blade failure occurred. Macro and microscopic examination along with metallurgical analysis of the failed mower blade revealed that cracks introduced during the heat treating process were to blame for the failure. The cracks during heat treatment were due to poor quality control on the part of the mower blade manufacturer. Photograph A shows magnetic particle, black light inspection revealing heat treatment cracks on mower blade hole.
Photograph A Mower blade cracks introduced during heat treating process.