I'm getting to the point where I need to know specifically how to use it, can somebody please explain it to me in detail?
thanks guys,

bushman

Are you asking about the Rockwell hardness scales that are used to measure the resistance of a given metal to surface indentation? Bill Harsey

Yes I think that's the one, I have a carbon steel Mora Steel knife with a hardness of 62 in the centre (laminated steel), what is that like in relation to most carbon or stainless knives?
cheers,

bushman

"Rockwell hardness (RH-)
a measure of the hardness of a metal introduced by Rockwell in 1922. In a Rockwell hardness test, a penetrator makes an indentation in the metal under two constant loads, a "minor" load (generally 10 kilograms) and then a "major" load. The difference in penetration depth between the two loads provides the measure of the hardness, usually read from a gauge on the testing machine. There are several Rockwell scales for different ranges of hardness. The most common are the B scale (RHB), for which a steel ball is used as the penetrator, and the C scale (RHC), for which a cone-shaped diamond is used. The B scale is appropriate for soft metals, the C scale for hard metals. Rockwell hardness numbers are not proportional to Brinell or Vickers hardness readings.
rod (rd)"



That's it- I am not sure what you mean by "use it"- Anyway, 62 HRc is very hard steel, which also makes it very brittle- that's why some blade manufacturers sandwich that hard blade between two softer layers in order to hold it in place without breaking.

Many other very fine blades are tempered to 57-60 HRc, making a good compromise between edge retention and toughness.

Thanks dBu24, I was going to use it as a guide for buying knives or getting one made to my own design, also just curious as to how it worked. What knives do you keep by the way?

bushman

The best use of the Rockwell hardness scale is for the heat treater to keep track of getting a known steel to a particular point of hardness while keeping very careful watch over the time and tempuratures used to heat treat. The goal being that fine line of both edge holding and toughness for a given job. Their are many wrong ways to get the right Rockwell hardness no. during heat treat. Rockwell hardness readings, which are very well explained in a previous post here, do not tell us the wear resistance or toughness of a steel in comparison to others. You could have two different steels with exactly the same Rockwell hardness no. that have very different qualities of edge holding and toughness. The metallurgy books define steel in it's simplest form as being made of Iron and carbon. Enough carbon in the steel makes it hardenable by heating and cooling. The difference between tool steels comes from the alloys (and percentage of same) used in the initial melt, some form carbides, some go to the matrix that hold the carbides, others work to improve grain structure and make the steel respond better to heat treat.. Their is nothing wrong with the knife you describe, lamination is a great way to make a strong knife that holds an edge very well.