Full tang: tempered or soft?

[Alarion]

I leave the tangs in my knives at the annealed state. I just heat treat the blade and 1/3rd of the tang.
This is due to the limits of my small forge on the big ones, and a choice on the small ones. The tang has to be resilient, not super hard. Tang on swords were left annealed.
Is this OK?
Is there some mistake in my reasoning?

 

[Joss]

I think this is fine. In fact, you could even leave parts of the blade soft too - this is the differential hardening which I'm sure you're familiar with.

ABS MS Rob Hudson use a technique whereby the tang goes all the way through the handle and a hole in the buttplate. He then use a ball pein hammer to upset the tang. Of course, this is done cold and requires the tang be perfectly annealed.

Personally, I do my machining in a normalized condition rather than fully annealed. With the simple steels I use (1084 mostly), I can't feel much of a difference, even though I use hand files exclusively.

 

[the possum]

Gentlemen,
I have a slightly different opinion on the matter. For small knives, I guess it doesn't really matter much one way or the other, but on big knives where a lot of force will be applied to the handle, I would want the tang at least spring tempered. I have bent several tangs that had been left dead soft. If you're using a pretty solid handle material, it can help support the tang, and you might be able to leave the rear half of the tang soft. But if your handle is made from something like rubber or stacked leather, the tang must be strong enough to take all the stress by itself. Also, any time you put a pommel on a big chopping blade, the tang MUST be stong enough to sustain a lot of force. Dead soft will not do, especially if we start to discuss stick tangs. I'm sure you are aware of George Turner's "controversial" ideas on on sword impacts, but I believe his ideas about tangs and pommels were dead on. tangs and pommels (see also part 3)

Though I did reach my opinion long before reading that article.

 

[ddavelarsen]

Possum that's a good point and one I had not considered. Thanks for pointing that out. Most of my knives so far have been full tang so not an issue to leave soft, but I recently completed one that probably would not withstand the kind of use you describe; that sucks.

Which brings us to a big question. In the case where you plan to drill the butt cap and tang at the same time at final assembly, ie Wm Scagel type construction, how would you get around this? Harden and temper the initial section of tang and leave the end relatively soft?

Dave

 

[Alarion]

I agree with you on the stress, but most sword tangs are annealed. Jim Hrisoulas anyway anneals his sword tangs.

Anyway I'm speaking of a full tang with scales, not hidden tang. I don't see how it could be bent if not in using the knife as a prybar, which is not to be done anyway, and probably the point would fail much sooner than the tang...
The tang it's 3mm thick. Anyway, I can see your point. The tang of a knife takes different stress than that of a sword.