Crack failure of gears used in generating electricity equipment by wind power

A failure investigation had been conducted on the two failed gears which were used in generating electricity equipment by wind power. Fractography investigation on the cracked teeth indicates that the crack origins are about 3 mm from the groove and exhibits point-like features. The cracking nature of the two gears attributes to the once instantaneous cracking. Metallurgical analysis indicates that cracking of the teeth occurred during the carburization-quenching process. The presence of a number of inclusion clusters consisting of Al2O2 complex inclusions in the crack origin zones is mainly responsible for cracking of the gears.