I feel ashamed to ask...

[ThinkOfTheChildren]

While I consider myself to hold a fair amount of knowledge on knives, I often come face to face with an aspect of knives of which I have litte to no knowledge. So here's my newbie question for the month

I need more information about heat treats.

Does the heat treat of a blade go all the way through? I mean, if you wear down a blade a lot over a long time, will you get to a point where the steel you are using as the edge is no longer treated the way that the original edge was?

Also, can a mass production factory get stock steel pre-heat-treated or does a blade have to be ground before it is heat treated?

Please don't think less of me

 

[Richard]

Intetesting question, and one I will definately be following to see and answer to.

 

[mschwoeb]

Two things that might help:
I think that I have seen some knives advertized as having a different heat treat on the inside and out for some different abilities. cant remember any more that that.

Here is how buck knives does theres:
http://buckknives.com/cms/index.php?Category=6
just go all the way through the tour. shows that they cut out the blanks and do a fair bit of milling to the parts before tempering

 

[DC KNIVES]

First,the steel is heattreated all the way through.It's not just on the skin with a soft core if I understand what you are asking.As far as wearing down the edge far enough,could be but not likely.What you need to understand is that there are several methods used for heattreating.Not getting too technical,most stainless knives are heattreated then tempered at the proper temperature whole.Then you have carbon steel blades that can be done the same as stainless with different temp's.They can also be edge quenched or differentially tempered where the whole knife is quenched and the back drawn back to soft.It would be almost impossible the wear an edge that far without the knife being useless anyway.Knives are ground prior to heattreating.The only knife steels not requiring heattreating are the Talonite types.Hope this helps,Dave.

 

[ThinkOfTheChildren]

Thanks for the clarification!

 

[DC KNIVES]

I probably should say that Talonite and similar types are not steel but a different alloy composition.I don't want to confuse.Dave

 

[tom mayo]

Forged Knives that are Differentially Heat Treated have hard edges and soft backs. Those are all made by hand and samurai swords have been built that way for over a millenium.
Most of the knives you buy in a store or the ones from custom makers who use modern stainless steels are all the same hardness thruout.
Talonite and Stellite 6K are not heat treated but come right from the plant at rockwell 48-49 and are used like they are made.

Heat treating is done to High Carbon tool steel (just about everything we use these days falls into that category-High carbon=1% or more carbon content) to change the molecular structure of steel. It goes from austenite to marstinsite (hope i got that right) and is an entirely diffent molecule when finished. Hope that helps.

 

[Samurai6]

Actually, Barry and Lynn Dawson do a partial quench heat treatment on their 440C knives that leaves the thin part of the blade, namely the main bevel, fully hard but leaves a soft core at the spine where the steel is full thickness. Pretty cool. So there is an almost infinite variety of heat treatments out there, especially from the really creative and experienced heat treaters, but generally, the part of the blade that you can put an edge on should be uniformly hard.

 

[frank k]

Some one please correct me if I am wrong, but it is my understanding that there are a few exceptions to the normal hardened all the way through heat treatment, as mentioned by DC KNIVES. Tom Mayo mentioned differential heat treatments, others include case hardening (reportedly used may years ago for cheap knives), nitrating (Busse) or some form of super hard coating (not realy a heat treatment). The disadvantage to surface hardening, is that they should be sharpened on one side only (single edge bevel).