Delamination?

[instantramen]

Began noticing some separation between the cladding waves and the core steel on my sakai ichimonji mitsuhide deba - I can feel the bottom one slightly when I run my nail over it. Should I be concerned? Could this affect durability?

 

[blokey]

seems very slight, I wouldn’t be too worried

 

[refcast]

Suisin and Sakai motokane have put out little blurbs and posts that the small delamination or forging scar, is a sign of low temperature forge welding and results in a tougher, sharper steel.

As per suisin, blacksmiths can purposely stamp right on the lamination line to test whether the weld is strong enough despite any surface delamination. They mention Keijiro Doi specifically. If it breaks apart then it breaks right then, but if it stays together then it's good.

They also do say customers complain about it too, haha. It's a mixed bag. Some customers want the better steel HT with the delam, some want a cleaner looking knife

I've posted about this on the Japanese web list I have in kitchen knife knowledge

 

[Blank Blades.]

Definitely looks like a delam. But like blokey said. Should be fine.

For care. Make sure you clean that part well. And, moisture getting trapped in their would be the only real detriment to the overall lifespan of the knife. I wouldnt worry a ton. But if you are. Just make sure to use a bit of food safe oil on that part every now and then to drive out any moisture.

 

[blokey]

Suisin and Sakai motokane have put out little blurbs and posts that the small delamination or forging scar, is a sign of low temperature forge welding and results in a tougher, sharper steel.

As per suisin, blacksmiths can purposely stamp right on the lamination line to test whether the weld is strong enough despite any surface delamination. They mention Keijiro Doi specifically. If it breaks apart then it breaks right then, but if it stays together then it's good.

They also do say customers complain about it too, haha. It's a mixed bag. Some customers want the better steel HT with the delam, some want a cleaner looking knife

I've posted about this on the Japanese web list I have in kitchen knife knowledge

View attachment 262340

Very interesting, Ichimonji also told me about low temperature forged knives are tougher and have more edge retention.

Definitely looks like a delam. But like blokey said. Should be fine.

For care. Make sure you clean that part well. And, moisture getting trapped in their would be the only real detriment to the overall lifespan of the knife. I wouldnt worry a ton. But if you are. Just make sure to use a bit of food safe oil on that part every now and then to drive out any moisture.

some board wax would be good too, just stuff the little bit of space there

 

[Blank Blades.]

Very interesting, Ichimonji also told me about low temperature forged knives are tougher and have more edge retention.

some board wax would be good too, just stuff the little bit of space there

The only actual benefit that is going to come from low temp forge welding is less carbon migration. They could definitely forge weld hot enough to get solid welds, and not have any actual issues otherwise. unless they are going extremely hot.

Anything involved with toughness really shouldn't be effected too much by a hotter forge weld. Except for maybe a few conditions.

1 they went so hot they started melting grain boundaries.
2 they aren't thermocycling after forging in anyway. Which seems like a bad idea, even if they weren't forge welding, and also cold forged/plantish at the end of their forging.

Well. I say that. Really with lower forging temps, it should have lower carbon migration, which means the steel should be able to be hardened better. (One last edit, i said this part because potentially higher hardness, will correlate to lower toughness. I mean it does correlate to that. Just to what degree depends on a lot of different things)

Also. There is one way it would help with toughness potentially. But. It really has nothing to do with them forge welding.

Actual cold forging at the end of the forging process, after annealing. Will potentially lead to grain refinement, and with simple steels like these. Grain refinement can mean a bit more toughness. But saying that has anything to do with not getting a perfect weld is misleading on their part if its what they are implying.

 

[refcast]

@blokey

The ones with delam almost always sharpened nicer and sharper and easier than ones without. The prelam ones have nice and really soft iron though, kind of distinctly so, they've felt similar to me. Wavier lamination lines usually means more forging, but not always. There have been some with very subtle waves in the lamination line that have been exceptionally great at edge taking. Also the thicker the knife is, the less lamination line undulation there usually is. Perfectly straight lamination lines knives usually aren't the best feeling knives, but I use all sorts of quality of knives, and it's not the biggest deal

 

[instantramen]

Suisin and Sakai motokane have put out little blurbs and posts that the small delamination or forging scar, is a sign of low temperature forge welding and results in a tougher, sharper steel.

This is fascinating, I'd never heard of this before. Thanks for the education

 

[TB_London]

If you get carbon steel too hot in a forge it turns to cheese. The hotter it is the easier it is to weld though.
Smiths like to demonstrate skill and so being able to set a weld at a lower temperature is a way of showing skill in the control of the forge and the material. Welding without the use of flux is another thing that shows skill.

These shows of skill can lead to a better product not just because of the lower weld temp but the better control over the forging process.

The downside is you may not get a good weld. In the instance shown I think it’s just a bit of trapped crud at the weld line, inclusions can happen to everyone, especially when flux free, and solid fuel forges.

If you’re worried dry it well and warm it with a hairdryer then drop some thin superglue in to fill it. Any over spill can then be buffed away, and you won’t have to worry about moisture getting in.