Heat Treat

Terrill · May 25, 2001

I was talking to a maker today about heat treating. He has had two different heat treaters tell him that they will treat his blades, but that they will come out within a range of hardness. Am I wrong in thinking that a good heat treater should be able to give an exact hardness that a blade will be?
While I am at it, for my education, what hardness should the different steels be treated to hold a good edge yet still be able to be resharpened without a lot of pain? The million dollar question!

------------------
It's never too late to have a happy childhood!
Terrill Hoffman Knife Photography photopoint
My Services

Chiro75 · May 25, 2001

I imagine heat treaters like to give a range for two reasons:

1) Variances in the oven temperature cause slightly different hardnesses, and the steel composition can vary a bit maybe giving different properties after heat treating.

2) To cover their butts. If you tell a maker "That knife will have a hardness of 58.5, and it comes out 57, then the guy turned into a liar. If he says "It'll be 57-58 or so, then he is covered.

------------------
Dr. Steve Agocs
http://www.geocities.com/Chiro75/frames.html

agocs_s@hotmail.com

Don Cowles · May 25, 2001

Terrill, the range given is usually small (2 points), so the difference in performace from the bottom to the top of the range would be extremely difficult to measure.

When you choose a lower range, you are buying toughness (ductility) and easier sharpenability. A higher range gives you greater edge holding capability, but more brittleness. Everything is a compromise in the final analysis.

Don Cowles
www.cowlesknives.com