Posted by Gordon England on February 06, 2004 at 00:45:21:
In Reply to: testing for nitride coating posted by Larry Weed on February 06, 2004 at 00:03:53:
: My company orders a product that is nitrided and we wish to verify it with hardness testing. Initially the supplier said that it should come in as a Rockwell C 69 or higher equivilant to Vickers 1000+. When our lab tests it it reads 25 RHC. Now the supplier says that you can't convert Vickers 1000+ to Rockwell C. So my question is, "What is the proper way to verify the nitride coating? Can it be tested with Rockwell or can it only be tested with Vickers?". There is quite the dispute going on.
Hi Larry
It will depend very much on the thickness of the nitrided layer. I think you would require an effective case depth of at least 0.028" to get a reliable reading from the Rockwell C scale.
Vickers hardness test would be the best method to verify the hardness, but failing this you could try the Rockwell Superficial scales (or possibly Rockwell A if nitrided layer is thick +0.012").
Regards Gordon
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