PDA

View Full Version : Rockwell Scale and relative hardness



dav
04-19-2012, 03:09 PM
Partly out of interest but also partly wanting to understand the properties of the knives I have or will purchase I was wondering how much harder an increase of 1 was on the Rockwell (HRC) scale of say 60 to 61.

I'm aware of how this is tested/done and my "research" seems to show that for every increase of 1 the depth of the "dent" caused increases by .002mm so does this equate to an increased hardness of 100% for each increase of 1 on the Rockwell scale or is there an algorithm involved as I'm sure its probably not quite that simple?

DevinT
04-20-2012, 01:54 AM
Most knife/tool steels in the annealed condition are between ~15-28 hrc. A "spring temper" is in the mid 40's hrc. Most knives should fall between 58 and 64 with some exceptions. I've seen the results of several cutting tests which show that with an increase of two points of hardness results in an increase of 15%-20% in edge holding. This only applies when using the same steel.

Higher hardness results in a decrease in the size of the dent. Not sure if that answers your question.

Hoss

ggg16902002
04-20-2012, 02:51 AM
Increase of 1 degree on the Rockwell (HRC) scale equates to an increased hardness of 10%.
I hope it answers your question.

dav
04-20-2012, 11:43 AM
Many thanks both, yes indeed my question has been answered. I'm aware its not the be all and end all but was curious non the less.