Failure of a diesel engine injector nozzle by cavitation damage

A failure investigation has been conducted on a diesel engine injector nozzle used in a truck, which is made from 18CrNi8, a case hardening steel. The nozzle has been found cracked after about 400 h in service. An evaluation of the failed injector nozzle was undertaken to assess its integrity that included a visual examination, photo documentation, chemical analysis, micro-hardness measurement, and metallographic examination. The failure zones were examined with the help of a scanning electron microscope equipped with EDX facility. Results indicate that the failure occurred because of cavitation damage in the internal surface of the nozzle followed by fatigue cracking.