@arun and @mw1st, i have done another back up investigation, and i found that the problem ring is on this three conditions : some ring have some black dust on the appearance (i am sure this is the product of decarburization), some other have a black-sticky layer on its raceway (which reveal the...
@mw1st : the final hardness is 61 - 64 for bearing products. We conduct our heat treatment process in a batch furnace and a conveyor furnace. Thanks for your advice, i'll look into it.
@redpicker : well, the element analysis shows that the ring is still 52100. I'll check again for your advice...
Last week my company had some problems regarding the hardness of bearing steel after heat treatment. Bearing ring , AISI 52100, (inner and outer) was found after heat treatment process, having low hardness.
Before HT : 8 - 13 HRc
After HT : 61 - 64 HRc
Problem Ring : 18 - 22 HRc
After...