Unidentified rusting object

T

themadarcher

Joined
May 22, 2007
Messages
22
Hi all,
I've got an old saw mill blade measuring about 20'' across by about 1/8'' thick. I was wondering if anyone out there knows the type of metal that these mill blades are made out of. I was told that it was an old saw mill blade, and is of very good knife making metal. It seems very hard as no tool I own will make dent in under an hour! It seems I will have to de-temper it. Just wondering if anyone may know its composition or suggestions on what I might do with it.
Cheers.
 
Wayne Goddard once told me that alot of those old saw blades are L-6 type steel that has a high nickel content, and make excellent knives. I have one thats about 3 foot across that I plan on cutting up soon. Those suckers are heavy!
 
In David Boye's book, he uses those giant saw blades, cuts knives to shape with a torch.
 
Welcome to Bladeforums!

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tknife said:
In David Boye's book, he uses those giant saw blades, cuts knives to shape with a torch.
Click to expand...

I think I've seen that book. When he gets done cutting out blanks, the remnants of the blade looks like a work of art, almost filagreed. :cool:
 
Nobody knows - it's a 'mystery steel'. Cut out a piece and see how it hardens.I would probably do best as a chopper.
 
Thanks all,
A knife made out of 'mystery steel' sounds cool. Maybe I could tell people it was from an asteroid of something. I figure it will sit where it is for another few years before I get the gas bottles recharged. Sounds like the best thing to do would be to throw it in a furnace and fully anneal it. Then I could hack out the blanks and re temper them individualy....Or I could just buy 1!
Thanks, Stephen
 
Cut a strip off of it and cut that strip into one inch squares. Heat to 1450 to 1500 and find where non magnetic ocurrs. Hold that heat for about 10 minutes and quench in warm oil. Hardness test them after cleaning up a bit. Temper the first 5 at 300 - 350 - 400 - 450 - 500 and hardness test. Use the last five to refine your tempering to what you want.

IMHO, mystery steel should not be used without a moderately accurate hardness tester - and I don't count a 'file test' in that category.

If you have enough of the steel to use after this test, you are right, it is very cool to recycle steel with a history behind it.

If you are looking for a starting 'SWAG' (scientific wild assed guess), L6 or 15N20 might have some potential.

Let us know how your exploration turns out.

Rob!
 
You could also send a small sample to be analyzed, that works well too, plus if it turns out to be a good steel you'll only have used a small part of it.
 
If you are going to cut out strips to test, use a zip cut on a grinder or a plasma cutter (if you aren't going to anneal first). I wouldn't use a o/a torch as the heat input is high enough to skew your results (especially in the area around the kerf). Your best bet is to anneal first, although it would help to know the steel type first.
 
I can't tell you how many saw blades I've tested for people, and have yet to find one that is L6 steel. David Boye lies. I love his book, and I'm sure it was unintentional, but the saw steel and L6 is a fallacy. Obviously I haven't tested every saw blade, and I've yet to test a REALLY big one so maybe they are, but I sure have'nt found any others that were. Most are either 8670m or 1070 steel. Both can make good blades. One and only one was 15n20. I would take Rob's advice.
Matt Doyle
 
Thanks for the help, but the more I hear, the more it seems that I'm over my head! I think I might have to start off making knives from files or something as this all seems very technical for somebody out to try making their first knife! Thanks for the suggestions, it's good to know that it would probably make a good knife, but it all seems to complicated for me.
Stephen.
 
Files are the same problem. You don't know what steel they are. Heat Treat is the soul of the blade. It's important to get it right.

You can get known blade steels CHEAP and then you know what you are working with. A 9" piece of 1/8 x 1 1/2 440C should cost you around the $7 - $8 mark and 1095 would be half that. You'd have to outsource heat treat of the 440C but the 1095 could even be done yourself.

Rob!
 
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