# Who can weld hardened stainless steel (Niolox)?



## Matus

The following mishap happend when I was shaping a tang on otherwise nearly fully ground blade. I had the blade clamped in a file guide to get nice 'shoulders' and so while grinding the tang on my 1x30" the tang was not lying flat on the workrest, but was unsupported. Plus the tang in the space where it was clamped was slightly thicker at the spine than closer to the heel, so it was clamped basically at a single point.

I was nearly finished, when the sound of the tang being ground (I was grinding the spine to adjust the height) suddenly changed and a second later the tang broke. It was a very non-violent process (the 1x30" as 250W, so it is more of a 'steel whisperer').

I was really surprised by this, but consultation with an engineer (my father) revealed that this kind of fracture (induced by vibration in a very hard steel) may really happen. Indeed - the fracture started exactly at the point where the blade was clamped, not where it was at its thinnest

I was told, that in theory it might be possible to weld the two pieces together, but since it is a stainless steel that is a more complicated process.

I am looking for someone who would be willing to give it a try. I fully understand that this may not work. I will anyhow make a new blade (this one is actually a custom order - from a VERY patient and kind customer), but if I could save this one it would be great as a lot of work went into it already.

Thanks 

Here a few photos:


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## valgard

Dang Matus, good luck finding someone who can weld it. That one was looking so good too.


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## Nemo

Sorry Matus no idea about the welding.

Nice looking' blade though. Hopefully it can be resurrected.

How do you find Niolox to work with? Is it as abrasion resistant as they say?

I have Chadd Smith making me a gyuto in Niolox. He said it is very difficult to mirror polish them, so I went with a sort of migaki finish.


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## dwalker

I have a guy local to me that has a laser welder. He routinely welds hard exotic materials. It would be no problem for me to take it to him as I am there almost every week.


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## tsuriru

It is possible to weld SS under Argon. However, while this is possible, I dont think I would recommend it for this particular knife.


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## Matus

The niolox is a *****  It eats belts and sandpaper. I needed two Norton Blaze 40 belts (in 1x30" size) to finish grinding of a 180 blade (that was partially ground before HT).

I am still finding the right way to give it a nice satin finish - it somehow tends to start polishing already with grit 240 (I am not sayinig it is easy to get a mirror polish). 

I have three 210 mm gyutos of the same design in the pipeline (after HT, but waiting for other projects to be finished first) - AEB-L (HRC63), D2 (HRC63) and Niolox (HRC61) to learn more about the differences. But I can already tell that AEB-L is easier to grind than Niolox and Niolox is stiffer than AEB-L. 

The reason for 'only' HRC61 is that I was told by Jürgen Schanz (he uses the steel a lot and has a lot of experience) that past HRC61 the steel just gets more brittle, but the edge retention does not improve. The edge retention is great, BTW  Sharpening seems easier than the D2, but that will be tested later on.


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## chefcomesback

You can weld it however it needs to be annealed and re heat treated , you will have retained austenite , cryo will help . Make a smaller knife out of it , my advice would be that


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## Matus

Thank you. I have hoped that it would have been possible to keep the blade cool enough so that only standard tempering (to about 200 deg C or whatever the value for Niolox is) would be enbough.

dwalker - I will drop you a PM soon 

Making a smaller knife is indeed an option, but to grind that much material away will be a PITA - I am not quite sure it would be worth that much effort (and that many belts)


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## Beau Nidle

I have actually welded stainless steel before, but I did so using a regular mild steel welding wire. This meant that the weld wasn't stainless, but since it was further down the tang and would be covered by the handle I didn't consider it too important. I didn't need to anneal and redo the HT, but again it was in a much less critical point on the blade.


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## tsuriru

there are 316L rods that, if done under inert gas properly will be completely inert afterwards. It is also possible to submerge the blade in coolant to a level just under the weld and so reduce the heat effected area. HOWEVER, and I say this as someone who knows the pain of loosing hours of work to things like this: Its better to just start over. These things happen from time to time, its part of making blades.


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## Matus

I will definitely start over for this project. I consider saving the blade to belong in the 'Nice to have' category. This failure was a valuable lesson learned even though it could have happend on one of my own testing blades, not a custom order. But Mr. Murphy rarely sleeps


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## dwalker

I don't know if you guys are familiar with laser welding, but the heat generated is VERY localized. The welder will hold it in his bare hand just a few centimeters away from the welding point. The edge will very likely not even get warm.


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## jessf

Isn't there a japanese carbon blade with a SS tang welded to it? I'd say you've got a jump start on a petty.


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## Dave Martell

Always, always, always do ALL profile work BEFORE grinding....just sayin'


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## Matus

Dave, I hear you. I just tend to kee the tangs taller, so they are easier to hold in hand while grinding, BUT - I think I have a good reason to come up with some maki-shift handles that would just push on the tang for that purpose and, as you propose - do the tang shaping before grinding. I will however for now keep some metal close to the tip which helps to avoid broken tips (I saw that Don Nguyen does this and it seems like an interesting idea). It seems to work well for me for now.


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## Dave Martell

I'm sorry to see this happen to you Matus, I do know the feeling.


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## Kippington

Beau Nidle said:


> I have actually welded stainless steel before, but I did so using a regular mild steel welding wire. This meant that the weld wasn't stainless, but since it was further down the tang and would be covered by the handle I didn't consider it too important. I didn't need to anneal and redo the HT, but again it was in a much less critical point on the blade.



Yeah I would do this. Weld with mild steel then grind the choil back 20mm so that the weld is in the tang/handle. You won't need to re-heat treat if you do this, I believe it will actually toughen the tang.


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## chefcomesback

That's a good suggestion


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## JBroida

Nemo said:


> Sorry Matus no idea about the welding.
> 
> Nice looking' blade though. Hopefully it can be resurrected.
> 
> How do you find Niolox to work with? Is it as abrasion resistant as they say?
> 
> I have Chadd Smith making me a gyuto in Niolox. He said it is very difficult to mirror polish them, so I went with a sort of migaki finish.



Totally off topic, but worth stating from a Japanese language perspective... migaki means polished... within the scope of migaki is mirror polished. So, all mirror polishing is migaki but not all migaki is mirror polished.


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## Matus

You guys are awesome. Thank you  It seems that I already found to possibilities how to potentially save the blade. The idea with grinding the knife back a bit and thus moving the fracture inside the handle is a good one.


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## Nemo

JBroida said:


> Totally off topic, but worth stating from a Japanese language perspective... migaki means polished... within the scope of migaki is mirror polished. So, all mirror polishing is migaki but not all migaki is mirror polished.



Thanks for the clarification Jon. That does make sense.


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## RDalman

Yea get a mild tang welded on, grind clean to see you have a solid weld, temper, bend and check it will bend over itself rather than breaking, have the weld inside handle.


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## RDalman

If i where you i would lookup a local welding business, call them and talk, it's probably a two min job for them, maybe you could swing by and get it done.. Just explain the weld on phone so you hear they know how to weld it. A regular car mechanic will usually not have done welds like this. And like said, heat doesn't travel very fast, a wet piece of paper nearby is all the "safe" you need in case the heel atarts to feel too hot.


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## GRoc

jessf said:


> Isn't there a japanese carbon blade with a SS tang welded to it? I'd say you've got a jump start on a petty.



Moritaka (moritaka hamono) offers stainless tangs on their Aogami super knives. Their weld lines are easy to be identified, especially once you remove the kuruchi finish, or if you order polishefld (migaki) finish. Not sure which type of stainless steel they use though and when they do the weld (before or after heat treat).


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## Butters

Martensitic stainless steels really need pre and post heat treatments to prevent cracking, so I wouldn't try it on a hardened blade whilst trying to keep part of it cool. The problem with welding high carbon stainless is that it'll air harden on cooling so you'll have to at least temper it, and ideally stress relieve it immediately after welding, If you're welding dissimilar metals then the different expansion/contraction rates can also increase the potential for cracking. To add to the problems the thin sections of a knife don't hold heat well, so the pre heat would be tricky as the heat will dissipate before you start the weld.

That said it can be done. If it's just for a tang and you're using dissimilar metals I would probably just use 309 filler rods (with Tig) as they're widely available and relatively cheap. Have someone keep heat on the piece with a torch (only to 300C, a tempilstik comes in handy) then lay down the weld and get it into a kiln to stress relieve it. If it's not a hard use handle that should be enough for a solid weld, however personally I would want to thermal cycle it again to refine the grain before running the heat treating cycle. 

If you weld it while it's hardened and don't at least temper it again you will create a stressed joint that will fail, although perhaps not immediately. If you take it to a quality welding shop they'll probably do it for a case of beer. At least I would have done. 

Fwiw I'm a Boilermaker & coded welder (TIG & MMA to ASME IX & AS1796). I don't weld to that level now as I've been out of it for a good while, but I still do some work on custom bikes and occasional stainless parts. Plus the odd forge weld on the pointy things of course


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## merlijny2k

Aside from how best to weld it, how does one sell a reaired blade to a crowd as tough to please as custom knife buyers? Could that be the reason all the pro's first instinct is to give up on the project while the experienced amateurs see possibilities?


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## Butters

Agreed, it's a false economy as the time it would take and the risk of failure far outweighs another two or three inches of material.

That said a good weld done correctly can often be stronger than the parent material.


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## RDalman

Definately I agree too, generally not a solution worth the hassle/risk.

Because I know Matus grinder situation and the work he have put in, as well as knowing his customer for this knife, I think the welding solution can be a reasonable route, if they can get it done by someone who knows his welding and it holds up to a little bending, I think chances are tiny it will ever fail in the future, and if it would, Matus and the customer are close to each other, good guys and can probably handle it


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## merlijny2k

I think a weld is definitely doable and preferable to scrapping it. But then again i'm one who fiddles with hand tools so I clearly have the amateur instinct. It just struck me that all the pro's initially advised against it while it seems doable and wondered why.


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## Matus

merlijny2k said:


> I think a weld is definitely doable and preferable to scrapping it. But then again i'm one who fiddles with hand tools so I clearly have the amateur instinct. It just struck me that all the pro's initially advised against it while it seems doable and wondered why.



If I were a pro I would toss it too. You would just not put out a product with a potential flaw, or a product that directly shows mistake that happened in the process. If the welding of a tang would been intentional and part of the process, than it is a different story of course.

I will redo this knife for the custom order anyhow (for the reason I mentioned above), but I would like to see it finished and I am curios whether the welding will work. I have indeed found an arrangement with the customer (still, blessed be people with endless patience and kindness).

The blade will be shipped tomorrow for welding. I will report once it will come back. It may take a few weeks I guess.

Thanks to everyone who replied - I appreciate the opinions and experience shared.


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## WillC

Common stainless tool steels are a nightmare to weld, let alone high carbon stainless steels...... the weld will air harden forming micro cracks between the hot /cold material, tig is a very local heat, so would need a very careful approach the preheat and cooling....... welding a mild tang won't help this either, this issue will be at the boundary. 
Therefore if I were you I would just chuck it in the *uck bucket and start again. Practice makes perfect as they say.


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## cheflivengood

WillC said:


> Common stainless tool steels are a nightmare to weld, let alone high carbon stainless steels...... the weld will air harden forming micro cracks between the hot /cold material, tig is a very local heat, so would need a very careful approach the preheat and cooling....... welding a mild tang won't help this either, this issue will be at the boundary.
> Therefore if I were you I would just chuck it in the *uck bucket and start again. Practice makes perfect as they say.



This is like a bunch of chefs talking about how to resurrect a broken hollandaise sauce, when in the end it's easier to just start from scratch to get the best final product.


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## tsuriru

cheflivengood said:


> This is like a bunch of chefs talking about how to resurrect a broken hollandaise sauce, when in the end it's easier to just start from scratch to get the best final product.



That is hilarious ! :doublethumbsup:


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## Matus

Guys I got it  Let's just call this an experiment. I will test how well the weld holds before making any more work on the blade. I will definitely report if it should fail - you deserve your "I have told you so"


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## comet_sharp

Hey Matus. I did this today while attempting to straighten out some handle alignment. If you fight Gflex, it will win..
This knife was AEBL at 62. My buddy is a welding educator, took him 5 minutes. I believe he tig welded with 304 rod and very thin flexible Ti rod.





















-Trey


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## Matus

Trey, thank you. That looks good. Did you try to stress the weld to see how it holds up? That is going to be a nice nakiri.

My blade should be with the welder now


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## comet_sharp

Hey Matus. I put the blade in a bucket of water and torched/aor cooled the weld to draw it back a bit. Then applied about as much if not more pressure on the weld that i used to break it originally. I think the weld + having annealed tang is much stronger than it was before. That said still not sure what I'm gonna do with this one so I moved on to the next. Might just keep it, has an amazing grind haha.
-Trey


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## valgard

you can probably sell it as a "second" some would be all over it :whistling:


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## Matus

valgard said:


> you can probably sell it as a "second" some would be all over it :whistling:



All Moritakas would have to be sold as 'seconds' in that case


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## valgard

Matus said:


> All Moritakas would have to be sold as 'seconds' in that case



Was just teasing Trey :angel2:


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## Matus

valgard said:


> Was just teasing Trey :angel2:



Good 

BTW - I just got the news that the knife was welded successfully


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## valgard

Matus said:


> Good
> 
> BTW - I just got the news that the knife was welded successfully



nice! we expect pictures as always .


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## Matus

I will post some ASAP


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## qjlforever

thats really broken..


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## dwalker

qjlforever said:


> thats really broken..



Not anymore
.......damn.


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## Matus

Well, with the help from dwalker (thanks a lot!) the knife blade was successfully welded and is on its way back to me. The following photos are from dwalker:

This is how it looked after welding:






And then after some sanding:






I can only say that I am very impressed and very thankful


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## JBroida

that came out great


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## valgard

WOW, that's an awesome save. It came out very clean.


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## TheCaptain

Wait! Dwalker did that weld or did he track down someone for you? Sorry but I'm ocd about some things and that is one of the cleanest welds I've seen!


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## comet_sharp

That weld is beautiful! I left the weld on mine, figured it might be stronger and didn't plan on selling. Did torch the weld to soften it some and it survived the burn in / alignment process. Just slapped on some birdseye maple shoes


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## dwalker

I didn't weld it, it was done by a friend of mine that does very specialized welding. He uses a laser that is very precise. Heat is extremely localized which allows him to hold the parts with bare hands. The things he can do with it are nothing short of amazing. Here is a picture of the machine.


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## TheCaptain

I'm in awe! I seriously appreciate people who can do such amazing hand work.


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## milkbaby

Dannggg... that weld came out CLEAN! :doublethumbsup:


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## Matus

comet_sharp said:


> That weld is beautiful! I left the weld on mine, figured it might be stronger and didn't plan on selling. Did torch the weld to soften it some and it survived the burn in / alignment process. Just slapped on some birdseye maple shoes



You saved that one nicely! I am also starting to like thid kind of single piece handles (after stocking up on all posdible handle making stuff of course)


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## comet_sharp

The 1 piece handle was intimidating to me at first. Once I made a few mock tangs and bought a long drill bit it became quite fun . I put saw dust in the pre burnt in slot and do a final burn in with the knife and it holds super tight.
-Trey


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## comet_sharp

And thank you .


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## inferno

Awesome job!

If that was my knife I would have welded it with either 309 or 312 stainless, either tig or stick welder, about 30 amps per mm thickness or so.

I would have put the knife in a vase/tall glass/pipe/tube/whatever of water with only about 10mm sticking out of the water, to prevent the rest of the blade getting more than 100C. 
Then I would have heated the broken tang part to a few hundred degrees C (and also the broken off tang part) with a propane torch.
Removed it quickly and welded it, then down in the water again, and then "temper" the part sticking out of the water with the same torch (since you have basically reaustenized it, so now its brittle).


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## Matus

I would only add that I have been working on the blade and hope to have it finished soon. Then it will be time for a handle


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