Stainless HT foil

M

Marko Veselinovic

Joined
Aug 3, 2020
Messages
32
Hi,
Let me start by saying I do not live in US nor the European Union, so it is hard to buy (not impossible, but hard) stuff from stores located there.
I have also read on here that AISI 309 is the best choice for HT foil used with "super steels", I use Elmax and M390 which are the ones giving me problems, because they have high austenitizing temperature (M390 over 1100+c, 2000+F) and they also have long soak times.
The Only SS foil I might be able to get locally is AISI 304.
Do you think it will work? Possible issues I might have?
I was thinking to get it in 0.1mm (.004inch), I saw it was usually used at half that. Thinking is that might provide more time before the foil fails?

I use some 304 pins in the kiln to space and hold the blades, to be honest even after 100 cycles at high temperatures I do not see much oxidation, there is some but not much...
And I came to this idea when I saw TR maker selling 304 foil, but they do not advertise the upper temperature for it..
 
I have never heard of 304 stainless foil so looked it up. From what I have read working temperate tops out at around 1600°F for 304 stainless.
 
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I’ve never heard of 304 either, I use 321 and regularly run my oven at 1975 and haven’t had any problems. I know there’s a higher temp foil-309, but if you can’t get either of these obviously there no help. Maybe you can get a sample or small piece of the 304, give it a run and see what happens.
 
I think the TR foil won't be good for you
have a look here under heat resistance
- 304

Do EU suppliers not ship to Serbia?
 
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I am from Latvia, EU east corner, not all EU suppliers ship to us or shipping fees are, well, not pleasant, so I understand frustration. Said that, I know at least 5 suppliers, who have ss foil, 3 of them where I have made purchases in the last year. I can name them if it does not violate forum rules.
If you are working with steels like Elmax or M390, then price for ss foil failure is the price of that "supersteel", plus your time, belts, and cost to run heat treat. I wouldn't advise to use subpar product, for example - even if that 0,1mm locally sourced foil doesn't fail from oxidation, you are inviting new problem - foil envelope sides and especially corners will be too thick to ensure blade full contact with chill plates. You can get away with this if you are working with stock 3mm and up, anything below that and you risk poor contact, uneven chill rate, warpages.
I can only tell, what would I do. When I returned to knife making year ago, I needed so much various stuff. I tried to save money and make my own stuff when it was possible. But I learned very early, if you invest in good steel (like mentioned elmax or m390) then there better be no room for errors. I ended up with buying full roll of ss foil, 10 meters. Yes, it vas pricey. Yes, it will be decades of years before I use all that, but now I have one thing that is guaranteed. And it costs just like steel for 6-10 knives from "super steel". My advice - don't cut corners with heat treat.
 
HSC /// said:
Do EU suppliers not ship to Serbia?
Click to expand...
They do, it is a bit of a hassle. Just looking if I can use what is available if it would work.
lynx85 said:
I am from Latvia, EU east corner, not all EU suppliers ship to us or shipping fees are, well, not pleasant, so I understand frustration. Said that, I know at least 5 suppliers, who have ss foil, 3 of them where I have made purchases in the last year. I can name them if it does not violate forum rules.
If you are working with steels like Elmax or M390, then price for ss foil failure is the price of that "supersteel", plus your time, belts, and cost to run heat treat. I wouldn't advise to use subpar product, for example - even if that 0,1mm locally sourced foil doesn't fail from oxidation, you are inviting new problem - foil envelope sides and especially corners will be too thick to ensure blade full contact with chill plates. You can get away with this if you are working with stock 3mm and up, anything below that and you risk poor contact, uneven chill rate, warpages.
I can only tell, what would I do. When I returned to knife making year ago, I needed so much various stuff. I tried to save money and make my own stuff when it was possible. But I learned very early, if you invest in good steel (like mentioned elmax or m390) then there better be no room for errors. I ended up with buying full roll of ss foil, 10 meters. Yes, it vas pricey. Yes, it will be decades of years before I use all that, but now I have one thing that is guaranteed. And it costs just like steel for 6-10 knives from "super steel". My advice - don't cut corners with heat treat.
Click to expand...
Not looking to cut corners, that's why I asked. I usually use stock of 5+mm, and I always grind post HT.
As it stands I get some of my belts like gator and such from the EU and obviously the steel, looks like the best thing is to get the foil as well.
If it is not a problem, I would like to hear those suppliers, thanks!

And if I manage to get a sample of that 304 foil, I will test it and report what happened.
 
Ok, I think it is ok to name general names:
Brisa - they advertise to ship worldwide. Staineless foil available in 1 meter or full roll 10 meters. (Finland)
Eurotechni - 50x61cm up to 7,5meter roll (France)
Gobec - only full roll 7,5m (Austria)
Rockbladekilns - you can ask any dimension lenghtwise (Italy)
Nozirske-oceli - 1mx31cm up to 61cmx10meter roll (Czechia)
Use search function to find actual sites. As I understand links to direct products with prices is forbidden in forum.
 
lynx85 said:
Ok, I think it is ok to name general names:
Brisa - they advertise to ship worldwide. Staineless foil available in 1 meter or full roll 10 meters. (Finland)
Eurotechni - 50x61cm up to 7,5meter roll (France)
Gobec - only full roll 7,5m (Austria)
Rockbladekilns - you can ask any dimension lenghtwise (Italy)
Nozirske-oceli - 1mx31cm up to 61cmx10meter roll (Czechia)
Use search function to find actual sites. As I understand links to direct products with prices is forbidden in forum.
Click to expand...
Off topic but anyway I will ask .............. :) Can foil be used more than once ?
I watched this video and they look great after the first use ? And it seems to me that he opens them carefully for a reason ?

 
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As I said, if I use expensive steel, there better be no room for error - that includes guessing about ht foil.
 
Here is an update.
The SS foil I found in country is AISI 301 at 0.05mm or .002 inch.
It is meant for something else, and is hard/springy. If you fold and hammer on the fold it will crack. Do not think it was heat treated (pretty sure you can not do that to 301) but that could be to cold rolling.
Simple fix I did is to hit it with a hand torch, that annealed it enough to make an envelope and test it.

The piece of steel is an offcut of M390, that was run at 1130°C (2070F) for 30 minutes.
Here is the result:

https://imgur.com/WvA3oTb

https://imgur.com/CBOXp4c

As you can see the steel is unchanged, so is the inside of the envelope.
I would say it was a success.

It is not a big deal to heat the foil with a torch, but I am thinking of putting a whole roll of foil in the kiln and annealing it properly, your thought on that?

And just to clarify, it is a bit cheaper then the asking price on the websites of European suppliers, plus I can get it very easily. And if you add shipping, custom fees I would need to pay to get the "proper" stuff imported it adds up quite a bit...
I feel confident to run a knife in this, what do you think?
 
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It looks like a success but myself I’d still be nervous using it having to manipulate the foil to prevent cracking, it wouldn’t stop me from using it though. One thing I would do though is dust the blades with talcum powder to prevent any chance of the foil wanting to weld to the blade at those high temps.
 
When I HT something again, I will put some scrap in this used one and put it in the kiln again just for you :) . But that is too much of a risk, the foil is brittle, and it is quite burned up...
 
So I have been using this foil for some time now ( 301 AISI or more accurate 1.4310 )
HT-ed around 30+ blades in many different steels, not one issue. Only time I had a problem is when I put a piece of paper in the pack as I have heard online, reasoning being to burn oxygen inside the pack, when I did that I had a problem with a pack expanding and wanting to blow open. Just pack it tight and use some talcum powder ( which is a very good tip, compered to the paper thing :) )

I have also experimented greatly with reusing the pack for multiple HT. It is possible, and I do it, but in very specific cases. Now with steels that have austenitizing temperature over 1100c (2010f+) not possible, not worth a try.
Here is an example of MagnaCut steel, the foil pack is so oxidized you can tear it with your fingers now, but it can last long enough (not skimping on soak times) to protect a blade!

https://imgur.com/5aBUMVy

But for some steels you can use the foil two times no problem, in some of my testing (not using a knife for the fear of ruining it) I got 3 good uses, but too risky.
Another important point is to take the sharp edges off, the tip of the knife and other points can puncture the foil while you press the knife in HT plates. That obviously ruins the foil pack, and makes it unusable.

Thing to consider also is I grind my knives completely after HT, if your putting an almost finished blade in foil, I do not think using an old foil pack is a good idea.
The foil is not that expensive compared to other cost of the HT, so it is not the smartest idea to reuse foil, but I personalty will continue to use a foil pack for two times on steel such as N690.
Using and old pack as a second pack when double packing a knife for annealing is not a bad idea too!

Some photos from my HT

https://imgur.com/Iek1ZDP

https://imgur.com/OOzqBCc

https://imgur.com/TkxVdWX

In this one I put a piece of paper (I tried it two, or three more times, will NEVER do that again!) , it also got a layer of greenish stuff on the blade, my blades without paper come out much better!

https://imgur.com/rKCxiFb
 
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