Edge Only Quench - Pros & Cons

[tejas7]

What are the pros and cons of an edge only quench VS. hardening the whole blade and then drawing back the spine and upper portions.

Would one method be better on thicker blades while the other would be best of thinner?

Does a properly performed edge only quench leave the back of the blade in a totally annealed condition (assuming it was that way to start with)?

What Rockwell Hardness is most usually associated with a "spring temper"??? and is a "spring temper" on the spine of the blade the most desirable thing to have on a using knife?

[This message has been edited by tejas7 (edited 06 October 1999).]

 

[Ed Caffrey]

Here's my view on the edge quench. I believe it's the only way to go with "straight" steel blades. I have found no other way to achieve the combined qualities of an outstanding cutter, with the durability and toughness in one blade. There are always some trade offs with anything you do, and there are some makers who would rather harden the entire blade. One of the comments I have heard is: "I would rather have my blades break than bend!" Not me! If I'm in a situation where the conditions of use are that severe, I would hope that I could half way straighten out a bent blade with a rock, rather than have two sharp pieces of steel in my hand.
I stopped Rc testing my blades almost 5 years ago, because they always came out the same......Rc 58-59 on the edge, and Rc 38-40 (for 5160), and Rc 40-42 (for 52100) at the spine.
Damascus is the one exception for edge quenching, unless you are certain it will be a "user". The reason being that when a damascus blade is edge quenched, and later etched, there is a distinct differenc between the hardened and non-hardened areas, which may be less than attractive on larger blades. The edge quench can be tailored to specific functions also. By increasing or decreasing the depth of the edge quench you can produce a "wimpy" blade that is easy to flex, or a blade that is super tough to flex. A correctly heat treated (edge quenched) 5160 or 52100 blade, that is edge quenched to within 1/4" of the spine will flex 90 degrees without breaking.
The best teacher is experience and experimentation. Not only will you develop methods and procedures that work for you, in your shop, you will also derive a greater confidence in you blades.
http://www.mtn-webtech.com/~caffrey

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Ed Caffrey
"The Montana Bladesmith"




[This message has been edited by Ed Caffrey (edited 06 October 1999).]

 

[Darrel Ralph]

In tests I have done the edge quench blades cut better . Thats all Ill say.. As for full hard the draw the back its not the same at least in my tests.. As Ed says damascus is a different beast. For working knives thats what I do .. edge quench

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[tejas7]

All of that information makes a lot of sense. I have another related question though, What would be the approx rockwell hardness of a 5160 blade spine that has been hardened and then drawn back to a medium or dark blue color?

And...how far do you think that blade would bend before breaking (all else being equal)?