what to combine?

[junker]

i am currently working on a basic damascus billet for an americanized tanto style fighting knife (i hope), i currently have leaf spring, a 4wheeler driveshaft, and "knife steel i bought at acme industrial (im guessing around 80pts carbon) what other kinds of steel should i add in? im looking for contrast but mainly a finished carbon content around 90pts. advice would be much apreciated.

[Rich Hale]

As you likely know to take a guess at the finished carbon content of a layered forge welded billet you use figures on carbon content of the steels you put in the billet. Lets look at wot yo have listed. The "knife steel you purchased. Is around 80 pts. (when you buy new they should be able to tell you exactly) The leaf spring may be about anything. It really depends on the specifications that were sent out for the suppliers to submit bids on price and who they select and if that truly met the specs of the bid. But lets say it may be 1095 or it may be 5160. The driveshaft would likely not be a high carbon steel for that usage. A wild guess would be roughly 40pts. and that may be off by a lot.
Now if we push a pencil a bit and figure that your billet will end up with equal parts of each steel:
40pts+80pts+95pts. That would give the total billet a carbon percentage of a wee over 77pts.
Now lets figur thelower carbon content leaf;
40+80+60. Or a total carbon percentage of about 60pts.
Neither mix will give you any where near wot you said you wished it to have. And lets not forget that everytime you bring that billet up to welding heat there may be a loss of carbon pts as they are lost in the scale formed. Newer smiths tend to take more heats than those with more experience and a proberly set up forge loses less also.
Some more experienced smiths may be able to estimate carbon content fairly close by spark testing.
This has been here for a day or two and my wild guess is that no one wanted to spend the time it takes to fully answer a question like this. It is a dandy.
Here are a couple of thoughts use them or not: Rethink how much carbon you would like to have in the finished billet and pick carefully wot steel would be best for getting that C content. There is more to steel make up than carbon content.
Pick up a copy of the Complete Bladesmith by Dr Jim Hrousalas. It will give you hours up front of reading and will be an asset to you for as long as you wish to may blades.

[junker]

ill get the book as soon as i can, but can you give me an idea of some steels that i can use to up the carbon content of the billet? i have a suplier for most tool steels in my area but the guys behind the desk only know the names of the tool steel and not it's carbon content.

[Rich Hale]

I will pass on giving you that information for these reasons: Knife making is certainly easy enough that I have learned to do it. However I am a strong believer that to make something you should be sure of wot you want to make, have the skills to make it and understand at least most of wot is involved in doing it. I believe that just cookie stamping steel numbers into a billet and trying to weld it is the short cut to frustration and failure. You certainly cannot be in such a hurry that you would want to shortcut options that may make you at least have a chance for sucess. That book is not the only way you can get the information you wish. theree is alot of information on this site that will help you along. And by the way I would bet that everyone that sells steel has access to the contents of each steel they sell. And for sure you do. Look up the steel by name and or number with google. Wot you will find may be frustrating as it will be a list of numbers and percentages that will make more sense to you when you get a bit farther along.
Do not take this as putting you down for being a beginner. Just take it as a challenge and learn all you can from it.

[pkrankow]

Old files are typically 100+ pts of carbon or so. Newer files are often similar, but sometimes not.

Phil

[brucegodlesky]

Nickolson Black Diamond files are Generally in that 1.0 carbon range. If you find roller bearings that can be ID'ed as 52100 , they are in that range also.
Rich gives good advice.

[ThomasPowers]

Old Black Diamond files (not stamped Nicholson) were 1.2% C and if I was betting I'd bet the leaf spring was more likely to be 60 points than 95 points carbon.

To figure out the end amount you need to do a weight balance---notice that Rich did his calcs for *equal parts*. You can do the calc for unequal parts but you have to take in account how much of each.

(Pts alloy A x weight A + Pts alloy B x weight B + Pts alloy C x weight C...) / weight A + weight B + weight C +...

So you can see you want to keep the low C stuff a lot less than the high C stuff so things like pallet banding combined with files or even better bandsaw blade combined with files---use two higher C alloys and no lower C alloys and use the alloy materials for differentiation when etching not the carbon content.

[FredW]

Not sure why you are looking at a finished carbon content on a damascus billet. I suppose you can fold it a couple of dozen times while making the billet so the layers will be so thin the carbon will migrate throughout to make a billet with nearly the same carbon content throughout. If so then what is the point of making the Damascus. Folding that much negate any grain you may have but then again there won't be that much contrast with using just carbon steels anyway. I would put several layers of what you have together with the highest carbon content steel on the outside. That way whenever you fold the high carbon will be in the center and you will always have a high carbon edge.

However if you trying to take junk steels and weld them together to get a higher quality steel or just a consistant carbon content throughout, then I would do as these guys say. You did say you wanted a finished content of at least 90 point.

Fred

[pkrankow]

According to a study that was done, it takes 4 folds in half to make equal the carbon through all the layers from carbon migration.

http://www.lehigh.edu/symposium/2009/rceas/attach/NizolekPoster.pdf
http://easternny.asminternational.org/static/Static%20Files/IP/Magazine/AMP/V167/I02/amp16702p24.pdf?authtoken=ff40179c124d273467b5eb4e028279c54915de86

Phil

[junker]

thats really good to know, i was planning on welding the billet, then folding 2x, then twisting and then rolling it up into a spiral shape like a fruit rollup lol, hopefully that will be enough to cause adequate carbon migration.

[fciron]

Keep in mind that folding it 4 times will yield a stack with 16 times as many layers as the original (2x2x2x2=16). Folding it twice will only yield 4 times as many layers (2x2=4) Twisting and other manipulation of the bar will affect the pattern, but not the number of layers. The thinner (and more numerous) the layers the more consistent the final billet.

[junker]

rolling it wouldn't count as an extra layer if it was welded together that way?

[edge9001]

rolling it wouldn't count as an extra layer if it was welded together that way?

Personally I feel if you roll it like a fruit roll up and the flatten the roll and weld it into a billet then yes it would add to the layers. But what do I know, I'm just a guy from GA.

[fciron]

Personally I feel if you roll it like a fruit roll up and the flatten the roll and weld it into a billet then yes it would add to the layers. But what do I know, I'm just a guy from GA.

Whoops, my bad. Depending how many times it rolls you could double the layers one or more times. Gonna be an interesting weld though. ;)

[FredW]

Thanks Phil, that is good to know. This means if I use mild steel in my billet I am going to have to use a lot more high carbon to keep the carbon content high. Would make a much better knife.

So if I use the same size layer of each kind of steel, mild and 1095, and I use 3 layers of 1095 and 2 layers of mild (1018). I fold it 4 times and weld each time. 80 layers if use 5 peices of steel in billet. I am going to have a billet that is .678 carbon, if I did the math correctly. Not a terrible amount for a knife but not great. Would actually be less as carbon is lost during the welding process. Changes the way I am going to do things.

Fred

[ThomasPowers]

(3 x .95 + 2 x .18) / 5 = .642 if I did the math right and counting the size of each piece as "1" as they are all equal in size.

Now if you drop the mild and add in some medium---say .6 you then get .81 disregarding losses in the welding and forging.

[adamj]

i have a small cable knife that i welded up like a fruit roll up and it did fine made 5 layers

[junker]

i was thinkin along the lines of flattening the roll and then rolling it a second time. as depicted by my horrible microsoft paint skills. (and yes that is a fruit rollup)