Bent or Broken Does it matter?

Interesting comments so far looks like a good thread.
So far Bend seems to be the prefered result.
Had a gentleman over to the shop yesterday and was showing him a shock steel I am working with. Proceeded to whack the spine of a hardened bowie blade against the edge of my vice. He was standing there eyes bugging out after I showed him the divets in the vice and just cosmetic marks on the blade. Then dropped it from 4' up point first and he freaked. Took a divet out of the concrete and the point was dulled a little but resharpened in a few strokes. This stuff is called S5 shock steel and is used in industrial applications where high wear and pounding blows to the edge are common. The only issue is it's not Stainless, a REAL BEAR to grind and is also a bear to profile a blade from. This is a tough steel I am suprised has not caught on, probably because it is so hard to work with. I plan to keep using it in the near future.
 
All steels go through a transition from elastic to plastic deformation and then proceed to tearing / fracture, as you keep applying force. The question becomes do you want this to be a very sudden and explosive process or not. If your tip is bent and you would rather have it broken then work it back and forth until it breaks off, however if it breaks in a violent matter right away, it is hardly the fact that you can then work it back on so it is bent.

If the knife is bent and you can't put it back in the sheath then straighten it back out and then put it in the sheath. As for McClung's comments, his blades as a whole will tend to bend and not break as they are differentially hardened, I put a bend in one a TUSK. The edge is however ~62 RC and it will break with little flex, I took a large chuck out of the edge prying in wood (much bigger than a quarter).

-Cliff
 
Originally posted by RobertHankins
Horseclover
How about a drawing of that blade sounds interesting!
Click to expand...

You have to forgive the rant Robert, I was waiting out the clock to go to work.

The knife I was describing is, in fact, De Leon's jungle bowie. He does use ATS-34 but this thing is a brute. A bit like a Randall
Little Bear profile with no taper at all. He has some taper in the bevel grinds but the center runs full thickness to within an inch of the point.

I'll try to get a link to a picture up, I'll have to retreat to the real computer and upload it somewhere.

I bought this thing as a user and wouldn't hesitate taking a jab at a steel drum or digging a hole with it. It would probably fail at the first inch of the point.

BTW, love your stuff too. Your sales pics always get multiple views from me. (just waaay over budget like many) The S-5 sounds like tough stuff.

Cheers, I'll go work on the pic transfer.

GC

Here we go, Image was from Jim Berhings site where I bought he knife

deleonjpg.jpg


This is really a nice handle length for me, I don't end up palming the butt. It may seem out of proportion but that really is a 7+" blade
 
I think that the only time I'd be prying with one of my knives would be in an emergency, like, say, If I were trapped in a burning building with jammed locks. In that kind of situation, I'd probably rather that the blade break cleanly. If it bent, then it would most likely be considerably weakened in the area of the bend and, even if straightened, would just bend again in the same spot.

On the other hand, if the knife were to break cleanly near the tip or middle, I could just stick what's left of the blade in next to the broken-off fragment (or even use the fragment as a makeshift fulcrum, if I could) and keep going.
 
Esav brought up a valid point as to why it is better for the blade to bend rather than break and that is saftey of the user. If you are doing something with your knife that causes that much stress then a knife that bends would be preferable over one that breaks because the one that breaks like Esav stated, could potentially send you into the broken piece causing some nasty trauma. Not a good thing if you are out in the boonies or trying to escape someone or something.
25 years huh? Boy oh boy you must have some thick skin!:) I've been with my fiance for four and have had some hide removed but no thickening yet. When does it start to thicken?!:D :D :D Congrats Robert, in this day and age marriages don't seem to last that long. I hope I can have a marriage that succesful.
 
Apparently Robert must have had two visitors yesterday, if one of them was a gentleman.

In any case, Robert did the demonstration for me too, just yesterday, so I can vouch that I have seen it with mine own eyes and it is day-um tough steel.

Kinda felt sorry for the vise; what did it ever do to deserve such a mangling?:p

-Dave
 
I would rather it bend.
My JS test bowie was forged from 52100 and passed the performance test. After I recieved my JS stamp, I straightened it back out when I got home. Later I sent it and 4 other knives to Cliff Stamp to run some cutting tests with them. After I got them back, I hung the bowie knife on the wall. When I got married, I took it down and we cut the wedding cake with it (No Damage at all :) ) and then put it back on the wall. The knife does have a slight bend in it and it still cuts very good. Should last a long time just cutting wedding cakes :). I differentially harden all my blades except the damascus and then they get hardened all the way. I temper them right on the line of bend or break. I try to squeeze all the performance I can out of them without them breaking.
If it does bend, turn it over and do it again till it gets close to straight. I put mine on a stump and hit it with a hammer till I got it pretty close to straight.
This applies only to fixed blades as I would never use a folder to pry with (again). :)
I really don't see why a small knife would need to bend since you can't pry much with it anyway.
 
Why are we still talking about this? By now ways of making knives sharp enough to cut well and strong enough to be deployed in the severest situations are well known. I'm starting to feel that bladesmiths and knifemakers are trying in some cases to reinvent the wheel. There exist many treatises on metlurgy and heat treating that will tell anyone the specifications and means to get most steels to do just about anything you'd want them to do. But I suppose it gives us something to talk about.
 
Because: Every day there are new people interested in knives who are not makers! Everyday there are new people who hear about and use this Forum to learn!
Every day there are people who are new to Knifemaking Steelbeaters or Stock removal who are still learning and need to know.

This does one thing:
Promote the industry we make our living at!

We should consider it our priviledge to share and teach them that which has become second nature to us!
 
I would much rather have a blade take a bend than break. If it breaks you are screwed and out a knife and if its a survival situation you are now dead if thats your only knife that just broke. This is why i order most of my knives in tough carbon steel(L6, 5160, 1084, O1, 3V etc)because it can take the abuse and not break, i noticed most of the good stainless steels(BG42, D2, etc) will break rather than bend, im not sure why this is maybe one of the makers can shed some light on this for me. I do know however that S30V is almost as tough as most carbon tool steels, however it also costs ALOT more.
 
Rifter :

... i noticed most of the good stainless steels(BG42, D2, etc) will break rather than bend, im not sure why this is ...
Click to expand...

The heavy alloy content which induces segregated carbide formation. These carbide chains can't flex at all and thus they make the steel very resistant to taking any type of bend, as a permanent bend can only happen if the steel is allowed to move parts of it relative to other parts. When you have long strings of carbides gluing everything together this isn't going to happen. It isn't just stainless steels, very hard and high alloy steels in general are not very ductile, though stainless steels are among the worst as Cr is a coarse grain carbide former. Most of the simple steels are often differentially hardened as well and this makes them *far* more ductile than if they were full hard. It is rare to differentially harden a high alloy steel like a cutlery stainless as most of them will air harden rapidly.

-Cliff
 
I would rather have a knife bend. If you were in a survival situation and had to do some prying, you could always gradually increase the pressure on the blade and stop before the bend got so bad that the blade became non-functional, unless you decided whatever you were prying on was more important than the knife, which I doubt.
 
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