Carburizing is a commonly used method for increasing the strength and wear resistance of gearing. A
significant benefit of the carburization process is that compressive residual stresses are developed near the
surface due to phase transformations that occur during the post carburization heat treatment steps. After
carburization and heat treatment it is necessary to finish the gear by processes such as grinding or skiving.
These finishing processes develop the precise geometric form required while improving the surface finish.
Finishing processes change the residual stress imparted by carburization and subsequent heat treatment.
Residual stresses change during the finishing process due to the removal of material and stresses induced
from the machining operation.
Thispaperpresentstheresultsofastudyperformed tomeasurethechangein residual stressthatresultsfrom
the finish grinding of carburized gears. Residual stresses were measured in five gears using the x–ray
diffraction equipment in the Large Specimen Residual Stress Facility at Oak Ridge National Laboratory. Two
of the gears were hobbed, carburized, quenched and tempered, but not finished. The remaining three gears
were processed similarly, but were finish ground. The residual stresses were measured at 64 different
locations on a tooth from each gear. Residual stresses were also measured at fewer points on other teeth to
determine the tooth–to–tooth variation. Tooth profile measurements were also made of the finished and
unfinished gear samples.