In depends on the hardfacing technique and the final Fe dilution. Typical values range 42-45 HRC.
The Rockwell C Hardness for a grade 10.9 fastener is 32 - 39HRC or 320 - 380Hv10
it is 90
may be 75RHN
59RC
EN 31 having a more hardness than othres
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.
59
plan a fair test with timing......... bash each rock with a hammer and see which one breaks first
it is 90
may be 75RHN
59RC
7
No, because hardness is not a fundamental quality