Aritsugu Honyaki Yanagi Repair - Shirogami grain structure

[SilverSwarfer]

I bought this in 2012. It was damaged in 2015. The event that caused the crack is unknown. I had the knife on my station. I stepped away and when I returned, there was this crack. This was heartbreaking, I had spent big $$$ on this blade, and it was performing incredibly well. I was torn about what to do, and I experimented with continued use and sharpening. Experimentation was very limited. I wanted to see what might happen since the blade was already compromised. The result, as expected, was that the crack grew slowly.

I contacted the original dealer and asked them to reach out to Aritsugu, and to explore any possible repair options. They declined to 1) contact Aritsugu because they stopped carrying that brand and 2) attempt any repair because of the nature of the damage. They did offer me 20% off my next knife purchase plus free sharpening and engraving (I never use those services), which was a fine gesture.

This year I decided that the steel is more than worthy of continued service. I made contact with a knife shop and discussed the issue. The gentleman and I agreed to try and break the knife at the crack. The result is a very interesting 180mm utility knife.

In retrospect, the only thing I would change (aside from reversing the damage) is the grind at the tip. Specifically on the ura side. I may do some work to soften the corners but in use, it performs very nicely. Additionally, he sharpened the knife when he was finished, and added an unwanted microbevel. If I microbevel a yanagi at all, I prefer a very slight angle and a very slight width. This is a significant change to the edge and I have worked through some of this but It's still too much.

In the process, I have the opportunity to examine the grain structure of the honyaki Shirogami. I hope somebody else will think this is as interesting as I do!

Can anyone comment on the repair?
Is it possibly a flaw in the metallurgy?
Is there any reason this blade will not be sound for use?
Has any tradition been broken in modifying this yanagi for adapted use?

 

[refcast]

From a video that kippington showed, the most stressed point of a honyaki is where the crack started on yours. Can you show a picture focused on grain nearby the edge. The spine grain should be coarser, which it seems to be here.

 

[Bert2368]

https://www.google.com/amp/s/pmpasp...03/7-causes-for-quench-cracking-of-steel/amp/


From first glance, the shape and location of crack makes this look like it is caused by stress from quenching (you REALLY should send these pictures to manufacturer, if you can figure out how).

Do you have more clear, close up pictures of the broken surfaces showing textures?

A good look at surfaces of a break is generally needed for making a determination of failure mechanism(s) in steel.

If you have the broken off pieces still, and want to know for certain, microscopic examination by a trained person could be definitive.

https://www.google.com/amp/s/pmpasp...03/7-causes-for-quench-cracking-of-steel/amp/

Do you see the parallel markings near center of close up? These appear similar to the engineering drawing labeled as fatigue crack progression-

 

[SilverSwarfer]

View attachment 49655



View attachment 49643

https://www.google.com/amp/s/pmpasp...03/7-causes-for-quench-cracking-of-steel/amp/


From first glance, the shape and location of crack makes this look like it is caused by stress from quenching (you REALLY should send these pictures to manufacturer, if you can figure out how).

Do you have more clear, close up pictures of the broken surfaces showing textures?

A good look at surfaces of a break is generally needed for making a determination of failure mechanism(s) in steel.

If you have the broken off pieces still, and want to know for certain, microscopic examination by a trained person could be definitive.

https://www.google.com/amp/s/pmpasp...03/7-causes-for-quench-cracking-of-steel/amp/

Do you see the parallel markings near center of close up? These appear similar to the engineering drawing labeled as fatigue crack progression-

View attachment 49664

View attachment 49665

I still have the piece and would be extremely interested to contact Aritsugu on this, I have no idea how but will start digging. the surface in location of the original crack is corroded, it is difficult to see any texture.

The parallel markings you mentioned have to be from the force of the intentional break during repair.

If I clean the corroded surface would that compromise ability to determine potential quenching problem? This was my original thought, since honyaki is so difficult.

Who could I send the piece for further examination?

Here is another look.

 

[SilverSwarfer]

 

[Bert2368]

I wouldn't do anything to change the surface, such as cleaning. Keep it as close to original condition as you can.

If you are near a college or university campus, I would start with a call/email/visit to their mechanical engineering and/or materials science faculty.

With luck, a grad student or faculty member might care to do a failure analysis for the experience (or material for a publication). If not, they should be able to suggest a testing lab.

There are people here who can tell you "how to contact Aritsugu" I am pretty sure. Wait a bit for your post to be seen by some more members-

 

[osakajoe]

I’m going to play devils advocate here

Nothing will happen if you contact aritsugu. Even if you try and throw science at them. The fact is You used it for three years before it cracked so the argument can be made you put a lot of stress on it. No one would give you a refund or new knife. Had it arrived like that yes. You’re lucky you even got a discount and sharpening offer.

You may think you didn’t do any harm but from the pictures you’re overground your ura and may be applying too much pressure.

Was the knife ever cold then placed on a warm hot counter top or the opposite?

You sure no one touched your knife while you walked away?


I would take them up on that sharpening service and turn you knife into two knives. Ko-yanagiba by grinding the spine to the tip. And a Very small muki utility by grinding out a slightly longer tang to be placed into a handle.

 

[SilverSwarfer]

This

I’m going to play devils advocate here

Nothing will happen if you contact aritsugu. Even if you try and throw science at them. The fact is You used it for three years before it cracked so the argument can be made you put a lot of stress on it. No one would give you a refund or new knife. Had it arrived like that yes. You’re lucky you even got a discount and sharpening offer.

You may think you didn’t do any harm but from the pictures you’re overground your ura and may be applying too much pressure.

Was the knife ever cold then placed on a warm hot counter top or the opposite?

You sure no one touched your knife while you walked away?


I would take them up on that sharpening service and turn you knife into two knives. Ko-yanagiba by grinding the spine to the tip. And a Very small muki utility by grinding out a slightly longer tang to be placed into a handle.

offer was accepted years ago.

The knife was most likely broken by a hostess who got fired.

Any attempt to find more from Aritsugu would strictly be academic or to possibly allow them opportunity to consider some information from a user.

Again, thank you for pointing out my poor sharpening habits from years gone by. I practiced what I was taught and have learned in recent years after longtime bad habits, that I was doing it wrong for such a long time.

Always learning.

Also maybe some people out there can learn more from this and/or help me learn more. In my experience it is difficult to gain strong tutelage from practicing/competing chefs.

 

[milkbaby]

It's possible somebody dropped it or knocked it to the floor and caused it to crack. Somebody abusing it probably would've also damaged the edge which seems like wasn't the case? I doubt there is anything Aritsugu would find valuable to learn from examining the broken piece.

The corrosion isn't a big deal, you can break it again to examine how fine the grain is, though it's a small piece now and may be tougher to easily break again. Definitely use solid eye protection if you intend to do this. However, I personally don't think there is much to gain out of this other than perhaps to satisfy your own curiosity.

 

[SilverSwarfer]

It's possible somebody dropped it or knocked it to the floor and caused it to crack. Somebody abusing it probably would've also damaged the edge which seems like wasn't the case? I doubt there is anything Aritsugu would find valuable to learn from examining the broken piece.

The corrosion isn't a big deal, you can break it again to examine how fine the grain is, though it's a small piece now and may be tougher to easily break again. Definitely use solid eye protection if you intend to do this. However, I personally don't think there is much to gain out of this other than perhaps to satisfy your own curiosity.

My opinions is I gained a totally awesome and unique utility knife!

 

[Eric Chevallier]

Its look like a Usuba now
May be it would be better to change the handle for a Usuba handle to keep a good balance.

 

[SilverSwarfer]

Its look like a Usuba now
May be it would be better to change the handle for a Usuba handle to keep a good balance.

It does look like Usuba, especially how it was ground. It feels good in hand though and so I think I will keep it original.

In use, it is super handy and really great for all kinds of utility tasks on the station. Plus it's really easy to travel!

 

[Eric Chevallier]

I love when japanese knives live like this. I understand why you enjoy it