42 to 45 HRC
The Rockwell C Hardness for a grade 10.9 fastener is 32 - 39HRC or 320 - 380Hv10
may be 75RHN
59RC
it is 90
28 - 32 hrc
The initial load in Rockwell hardness test is 10KGf.
hardness as it is measured on a rockwell or brinell testing instrument
Rockwell hardness
The Rockwell C Hardness for a grade 10.9 fastener is 32 - 39HRC or 320 - 380Hv10
Both are two different scales of hardness measurement.
plan a fair test with timing......... bash each rock with a hammer and see which one breaks first
may be 75RHN
59RC
7
it is 90
No, because hardness is not a fundamental quality
Granite has a Rockwell hardness of 7, making it one of the hardest rocks. Talc scores a 1 on the scale, being extremely soft, whereas a diamond is rated at 10, the hardest known mineral.