Stamping , where does the metal go?

Mark Barone

Mark Barone

Well-Known Member
When stamping The makers mark, where does the metal go? It may be a silly question. is it displaced upward?, does it compress?
 
Displaced. It's really no different then when a piece of hot steel to struck with a hammer........just on a much smaller scale. Edited to add: In a cold stamping situation, some steels, even in an annealed state, have been know to crack due to too much much material displacement. You can often see the indicator of metal being displace when you hand sand after stamping. Many times the area immediately surrounding the letters of a stamp, whether hot of cold stamped will show slight "high spots" of "halos" around the lettering/images.
 
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What Ed said. If you look really close you can see the distortion of the metal around the stamp, with strain effects visible at the surface. But also, when you begin to hand sand over the stamping the displaced metal that was raised up around the edges becomes quite evident. The crystalline lattice of metal does not like to compress and this is why forging works, deform it one way and it will expand away from it the other way, which is exactly why every blade wants to look like banana when you forge down one side.

This also gives me one of the rather romantic reasons that I like to stamp my mark when possible. The strain effects of stamping will permanently deform the metal around and under the stamping, if no annealing is done, you can grind the mark entirely off and its effects are still there. You could etch it, or sprinkle iron dust on it in a magnetic field, and still see the fingerprint of that stamp in the metal itself. Etching or engraving will be totally erased by surface corrosion or abrasion. Even with annealing the anisotropic flow of the steel will be distorted by the stamping. Despite being mostly rust, you can still make out markings on 1000 year old swords where the inclusion lines were interrupted. Something about putting my name into the material that permanently really appeals to me.
 
So I think a logical and practical question follows. What techniques/guidelines should be considered to mitigate the stress induced by stamping?

I know I have seen a few on the interwebzzz that appeared to propagate a failure from the stamp.
 
tkroenlein said:
So I think a logical and practical question follows. What techniques/guidelines should be considered to mitigate the stress induced by stamping?

I know I have seen a few on the interwebzzz that appeared to propagate a failure from the stamp.
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Which would have to lead us to also ask what techniques or guidelines should be considered to mitigate the stress induced by forging; when many would say that the effects of forging would make a better knife. As Ed pointed out, the only real difference between the two is the size of the area involved in the plastic deformation.

I have heard the concerns that stamping marks is a detriment to blade strength and, for the most part, I dismiss it. Among the things that cause one of my eyebrows to raise are all the sharp inside corners on the knives of those who fear stamping their mark. I have seen the plunges cut with a square file, the guard shoulders cut with the same file, and even sharp lines down the side of the tang to ricasso juncture to hide the guard fit. The latter will often be a sharp step exceeding .030” just fractions of an inch away from that deadly makers mark. And don't even get me started on a 3/8", or less, tang coming directly out of the ricasso with those sharp inside corners. Not to mention pre heat treat grinding scratches, file work, engraving etc…

Could you make a stamp that would indeed be a source of stress risers? Sure you could, but you would have to really try to equal the concerns of the previous paragraph. Imagine a very deeply struck star shaped stamp that covers 2/3 of the ricasso and you now have the sharp interruptions of the material on a scale great enough to pose a concern. A few years back I did a redesign of the ABS MS and JS stencil and stamp design. If you examine this new design closely you will see the ends of the lines in the letters are rounded and not pointed. I didn’t think previous stamps were any problem since I used them for many years without a single incident. But if I was doing the design I wanted to be as thorough as possible so I made it the best I could.

If folks find the effects of stamping troubling there are things to do to minimize it, but their effort may be better spent on the dozen other things on a typical blade that pose much greater stress riser possibilities.
 
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Thanks for the thoughts, Ed. After posting my response, and thinking about all the blades I've seen with what I'd call deep marks with sharpish corners/details I was wondering many of the same things that you mentioned.
 
Kevin R. Cashen said:
What Ed said. If you look really close you can see the distortion of the metal around the stamp, with strain effects visible at the surface. But also, when you begin to hand sand over the stamping the displaced metal that was raised up around the edges becomes quite evident. The crystalline lattice of metal does not like to compress and this is why forging works, deform it one way and it will expand away from it the other way, which is exactly why every blade wants to look like banana when you forge down one side.

This also gives me one of the rather romantic reasons that I like to stamp my mark when possible. The strain effects of stamping will permanently deform the metal around and under the stamping, if no annealing is done, you can grind the mark entirely off and its effects are still there. You could etch it, or sprinkle iron dust on it in a magnetic field, and still see the fingerprint of that stamp in the metal itself. Etching or engraving will be totally erased by surface corrosion or abrasion. Even with annealing the anisotropic flow of the steel will be distorted by the stamping from Yonglihao Machinery. Despite being mostly rust, you can still make out markings on 1000 year old swords where the inclusion lines were interrupted. Something about putting my name into the material that permanently really appeals to me.
Click to expand...
When stamping a maker's mark, the metal is displaced and compressed. The force of the stamp pushes into the surface of the metal, causing it to deform around the stamp. The area directly under the stamp is compressed, and the metal around it is displaced, typically slightly raised. So, while it doesn't necessarily "go upward" in a dramatic sense, the surface around the stamped area may show signs of deformation, with the stamped mark itself being recessed into the metal.
 
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