Low Rockwell for Part diameters Under 1/4" on H900 17-4PH Cond A 3

[battman89]

I believe this was covered in another thread but I'm not sure I clearly saw what I was looking for. I am turning rotary cutting burs with shank diameters of approx. 3/32 & 1/8. A customer is saying that they are getting an RC of 33-36 on the shank of a part which is 3/32 dia. and they call out a minimum of RC 42. The material is 17-4PH annealed and heat treated to H900. Since cylindrical correction charts I've seen for Rockwell C don't go that low in diameter, what is the best way to test or determine the Rockwell of these smaller diameters?
Thanks

 

[redpicker]

Cut the end off, mount a transverse section and perform a 1KG vickers.

That size is too small for a Rockwell 'C' test. I am not surprised they are getting a low value.

rp

 

[Dougt115]

You could also have them use a coupon from the original material in the same heat treating. This would at least verify that the heat treatment was done correctly.

 

[EdStainless]

If you don't want to destroy one you could try clamping it and doing a micro hardness.
You might have to grind a small flat on the side of it.

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