Dear Colleagues.
Thank you very much for opinion in advance.
Regards, Ali
I think the upper limit for the Rockwell C hardness scale = 65 HRc depend on the ASTM standard:
(ASTM E18 Standard Method for Rockwell Hardness.
HRC, conical diamond indenter, 150kg load
65+ is the maximum reading for this range.)
Please, Can I get the primary reference for this above information?