Abstract: Many pockmarks were detected on the inner hole surface after grinding of a nitrided bearing housing made of stainless steel 2Cr13. The pockmarks were a lot of small area of exfoliation, as big as a needle, and could be seen by the naked eye. By analyzing the possible influencing factors such as materials, brittleness, stress and process, it is determined that the pockmark failure is caused by perchloroethylene added in nitriding process.

Key words: stainless steel, nitride, pockmark, exfoliation, perchloroethylene