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Carbon Barrier and Nickle Content


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I have been wondering if a steel that has a small to medium Nickle content such as 15n20 or 304SS

would present a partial Carbon barrier to slow Carbon migration?

Or does an alloy have to be almost pure nickle as in Nickle 200 to block carbon?

Thanks

Steve

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Steve in my experience it's hard to tell how much carbon migration is happening if say you are making PW with 1075-1095 using 15n20 or l-6 as a contrast layer. They are so close in carbon content anyway. My initial thoughts would tell me it doesn't make a barrier anywhere close to pure nickle, but.... I have made quite a few san mai billets with w-2 and 1095 cores using mild steel outer layers with a very thin layer of 15n20 between the 2 and didn't seem to experience any noticeable migration to the mild steel. There are a lot of factors that influence this such as time, temp, etc. I would like to see some concrete evidence either way as well.

 

Evan

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Evan,

Thanks for your input

I have been making alot of decorative billets with some 1008,hi mang.1074,15n20 and 1095.

I like some of the pattern enough to want to use it on some San Mai.

In the past year I have had what I call "smearing" from I guess using low carbon next to high carbon

and going through many welding heats.

I seem to have solved the problem by always placing 15N20 on both sides of the low carbon.

I can not say for sure the 15n20 is really slowing the blending of colors so I thought maybe someone

with a little more knowledge than myself could say for sure.

The silver of the 15n20 makes the nice blue -grey of this 1008 really pop regardless of the carbon movement.

Good Luck

Steve

Edited by bronzetools
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I thought Ric had mentioned on the forum that you need about 7% Ni to stop carbon migration... thats just going off my Fuzzy memory... :unsure: better to ask

 

P sorta stop carbon migration...or at least it chases C out of areas its in

 

do you have a picture of this " smearing " ?

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Greg,

I am sorry but I do not have any pics of the problem .

It mostly has been occuring with Mosaic billets after much manipulation.

I will see if I can find an example , then sand ,etch and take some pics.

Thanks for the input

Steve

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7% will not do much to slow anything.

It has to do with the "net" formed by the nickel...in reality is is the crystalline lattice of atoms. The nickel forms a lattice that carbon can not pass through.

To effectively stop carbon migration you need near 100% nickel.

 

It was actually Howard Clark and Dr. J. Verhoeven who did the experiments....I am sure there is a reference to the paper they published on this list as both I and Howard have posted the reference.

 

Do keep in mind that many atoms will migrate if there is time and temp enough, but for blademaking carbon is about the only one we really need be concerned with.....though hydrogen and nitrogen do move as well in the time/temp that we have. Other atoms require longer soak times...some in the range of 1,000's of years, but they do move.

 

 

Steve,

What you may be seeing is, for lack of a better phrase, carbon bleeding. The movement of carbon takes time and there is a driving effect which seems to make it load in higher concentrations in some areas and then bleed out from there. Like folk moving toward a doorway and then fanning out to fill the room.

There is still a large amount of study that can be done on this, but not many wish to take the time.

Given a longer soak I think your colors would be more even, but I would guess you are heating, making the weld and drawing out at a shorter time that the billet needs to get an even carbon level....so you have various amounts of carbon and this leads to the color differences.

Cut a section off and let it sit in the fire for the rest of the forging of another bar and then see what it looks like in comparison.

 

Ric

Richard Furrer

Door County Forgeworks

Sturgeon Bay, WI

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good stuff ! thanks Ric

 

also i remember reading that welding at the high end of weld temps was leading to the layers have a fuzzy look.... where the layers themself of the carbon steel and 15n20 were fuzzy, and the suggestion was to reduce the forge weld temperature.. some suggested that as the remedy

 

Greg

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high temp welding, borax and longer soaks lead to a white line between the welds. I am not exactly sure what that is, but it has been said it could be decarb or a boron reaction along the interface.

 

Ric

Richard Furrer

Door County Forgeworks

Sturgeon Bay, WI

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Rick,

Thanks for your reply.

As soon as I can get some spare time I will see if I can find a good example that will photograph well,

clean it up and etch it

I will also see if I can find the paper by howard and Dr.Verhoeven

Thanks Again

Steve

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