heat/stress risers and tang stamps

G

Gene Martin

Joined
Feb 5, 1999
Messages
1,068
When stamping tangs with names or other things, how much of a stress riser will that create for a problem to occur during heat treat? At the ABS school it was mentioned, on Fisk's making of a W pattern Sendero there was a problem, and I just had a crack appear on a stock removal blade from a stamp.

Is this a common problem? If so, why do so many stamp rather than etch their names or logos? My own problem arose in using a customer's stamp. I normally etch.

It strikes me that in giving the customer the most for their money, a stamp would create a potential problem that an etch would not.

I didn't want to hijack the thread on corners, so I started this new one. Same basic subject.

Gene
 
There are some new posts under that original thread with reference to logos which may be of interest to you to read.

Is it not a case of : It would have cracked whether there was a logo or not, it just happened to choose the path of marginally higher stress. (least resistance)?
 
When stamping damascus blades, if you are really walloping the stamp (to get a deep impression), you are moving the layers around and can create a crack when stamping. It is not always evident, but clearly shows up when the HT is done. I have done this a couple of times. Another good reason to anneal all blades prior to stamping, and normalize prior to HT.
Stacy
 
A while back statments were made that any sort of a step in forging would result in a weak point as well:rolleyes:. Hardening is not the only heat treatment, and is much less effective without the others to follow it up, it has already been mentioned, but it needs more stressing- normalize, normalize, normalize, and let's not forget simple stress relieving as well. If stamping a pattern into a blade is that detrimental then ladder pattern damascus has a fatal flaw every 1/4" or so of the blade, yet is seems to work:confused:hhmmmm

Edited to include: one could also consider the size and shape of the stamp. A small symetrical image would have little in common with a huge line stretching all the way from one side to the other.
 
Considering the tang has appx. twice as much cross sectional area as the blade, I don't see how a stamp could cause any stress riser issues.
 
I stamp most of my blades never had a problem , but I remember reading Ron Lake's section in how to make a folding knife year's ago and said he would never stamp a blade because of metal stress , he engraved them. Personally I am going to keep stamping mine .



Glenn Dykes
Louisiana
 
Thanks for all the info. The blade I had crack was 154CM, and it wouldn't have cracked there for any reason I know of. I've had blades crack due to not cleaning the edge after profiling, but I learned quick and haven't had that problem in a lot of years.
i appreciate the volume of good info here. it's nice to be able to look for potential problems so i can avoid them.

Gene
 
gene, my friend art summers stamped most of his blades until he switched to etching. i dont know if you use a hammer or not but art used a small press for his stamps and took his time. i have several of his knives, a few are 154 cm that have been stamped. none of these cracked. he put most of his stamps paralell along the spine. i dont know if this would make much difference and he never mentioned any cracking from being stamped.
 
The crack in the 154CM is what throws me. I do lots of blades in that and D2. Several years back I had 2 blades crck from heavy grind marls on the cutting edge prior to heat treat. I fixed that and have never had a problem since. That's why this crack threw me. The only difference is a tang stamp that I did with a hand held hammer. The stamp is purpendicular to the blade, parallel to the guard. I hand file all my tang shoulders square and radius the bottom of the cuts, so that wasn't the problem. The only difference between that blade and many others is the stamp.

I personally will play it safe and keep etching. I'm going to tell that customer no more stamping, get an etching machine. I figure one failure is one too many.

Gene
 
gene, have you tried using a press of some kind to stamp the blade instead of using a hammer? maybe thats why art never had a problem. he had a small gear driven hand operated press that worked very well.
 
I've not used a press. Thes is the first customer, a repeat customer, who wants a stamp on the blade. It sounds like in order to safely do that stamp I'll have to normalize and anneal the blade, stamp, then heat treat. If it was a knife I was making for me, I'd go through the extra effort. For blade blanks for a customer, I think it will cost more than he's willing to pay. He can get an etching machione, the stencils, and do what he'd like.

I do appreciate all the info, again. I used to watch Jim Ferguson use an arbor press and sledge hammer to put his name one blade. He seemed to escape problems, although I never asked him about it. What I've learned through this has been good. Hot rolled steel has a number of sresses built into it just by the process. Why create an extra that can be avoided? And now I know to anneal first before stanming on stock removal blades. I would have anyway on a forged blade.

Like I said earlier, lots to learn here and I appreciate the knowledge base.

Gene
 
IMVHO it depends on the stamp shape, which should not include any very deep and sharp corners, or you're looking for trouble.
Stamping surely creates a stress, but so does forging, which is not just ONE die put in the blade, but a HUNDRED hammer blows everywhere.
So, after stamping the annealed blade, normalize it and bye bye stress. ;)
I normalize my blades three times after any working on the blade (yes, grinding counts as work on the blade).
 
Gene Martin said:
I've not used a press. Thes is the first customer, a repeat customer, who wants a stamp on the blade. It sounds like in order to safely do that stamp I'll have to normalize and anneal the blade, stamp, then heat treat.
Click to expand...

Maybe here's the problem.
You did:
- normalize
- anneal
- stamp
- heat treat.

You should have done:
- normalize
- anneal
- stamp
- normalize
- normalize again
- heat treat.

but that's just me speaking.
 
Kevin R. Cashen said:
A while back statments were made that any sort of a step in forging would result in a weak point as well:rolleyes:. Hardening is not the only heat treatment, and is much less effective without the others to follow it up, it has already been mentioned, but it needs more stressing- normalize, normalize, normalize, and let's not forget simple stress relieving as well. If stamping a pattern into a blade is that detrimental then ladder pattern damascus has a fatal flaw every 1/4" or so of the blade, yet is seems to work:confused:hhmmmm

Edited to include: one could also consider the size and shape of the stamp. A small symetrical image would have little in common with a huge line stretching all the way from one side to the other.
Click to expand...

Kevin, I usually normalize thrice. Do you think this is excessive and paranoid, and twice should do, or should I continue this way?
 
I have never had a problem with cracking blades when stamping. As far as I can see. If a problems occurred most likely it was do to a miscalculation in the heat treat or the temping process. There are other problems that can cause the cracking. The steel could be too thin for heat treating and causing the stamp to penetrate to deeply in the blade. Over the years I have also learned that in temping there is no need to temper a blade more then once if it was done right the first-time. ----------:)
 
Alarion said:
Kevin, I usually normalize thrice. Do you think this is excessive and paranoid, and twice should do, or should I continue this way?
Click to expand...

Three is fine, as long as at least the first one is really good and hot. I used to go with the prevailing ideas about low temperatures for blade steels, but now I have been doing enough metallography that I am becoming a greater proponent of using heat to move sutff around, instead of barely kicking things over Ac1 and segregating things worse. If you really want to see cracking- get a heavy carbide laden band down the center of a piece that you failed to break up and then quench just a wee too fast!:eek: It will crack along that line every damned time.
 
I have never had a problem stamping knives in my 20 year plus of knifemaking. I work mainly with 440C. Prior to HT after all the grinding and drilling has been done, I spot heat the area on the tang that will be stamped to a cherry red with a torch. Strike once with hammer, clean it off with a quick pass on the grinder. Then move on to heat treat.

The only problem with this method is that you only have one chance with the hammer striking the stamp. The stamp better be even or it will leave an uneven impression which can be difficult to correct. With practice it gets better. Isn't that a big part of knifemaking anyways?
 
Bufford said:
I have never had a problem stamping knives in my 20 year plus of knifemaking. I work mainly with 440C. Prior to HT after all the grinding and drilling has been done, I spot heat the area on the tang that will be stamped to a cherry red with a torch. Strike once with hammer, clean it off with a quick pass on the grinder. Then move on to heat treat.
Click to expand...

Glad you've never had any problems but that sounds like trouble for an air hardening steel. I would bet it's not much softer heated to a red heat than in the annealed state. Have you tried it without heat? Maybe one of the metallurgists can comment on this.
 
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