Several heat treat steel questions

I

Inthewind

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Im new to the world of knifemaking (several months) and ive finished 2 knives and have several on their way to being finished (all of them made from an old saw blade off my grandparents farm).

These are the unfinished ones (the first one i did is my avatar)
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My first question is: Does anyone know what steel old saw blades are made of (50 years+ and 2.5-3 feet in diameter)?

I love using the old saw blades but they are kind of a pain to work with because i didn't anneal them because i didn't know what steel they were or how to heat treat them. If you do know the steel could you please tell me or direct me to a place with info on how to heat treat the steel?

Thanks.
 
Short answer: Most people won't have any clue what steel that is, getting a good heat treat is not likely to happen. Finding specs on a 50 year old saw blade may be nearly impossible.

Long Answer: You can try different things, and one of them may work well. If you really want to try, take a piece up to over 1414F, where a magnet won't stick, and heat a little while longer. Quench in Canola oil and test to see how hard it is compared to a file. If it's not all that hard, try warm brine, but be warned it could crack and in reality should have worked fine in Canola oil. If it's hard, temper at 300F. Check the hardness with a file, if it's only biting a little, take it to 450F and see what happens. I did this with some scrap/unknown for my first couple knives, and it worked fine, but they were files and a bit more predictable*. I assume of course that these are not any kind of stainless or don't contain too many alloys.

*I tested another file of the same brand before I did the rest, and did a bit of destructive testing to see how brittle/hard it was with oil, then water, and found that oil was sufficient, and then found a temperature that worked in tempering. My heats weren't controlled, so my info isn't anywhere near perfect, but it was something.

I'm no professional, and only have a few finished knives under my belt with a couple waiting to be heat treated. But trust me, buy some 1084, I can grind, file, and sand a knife in a couple hours to be heat treated and then finished. The files were annealed and took forever.
 
I would agree with blackfeather in general most tool stuff is high carbon and most of what you would do is just raise heat to non magnetic and quench then temper in your oven for 425ish.

if you have a cut off piece i would experiment with that to. I know m y first time heat treating iwent waaaaaaaay over non magnetic and burned my steel. So trying it on a scrap piece will give u experience and possible let you know if your heat treat combo will work. Also if you want to try again on the same piece annealing will be a good idea. Just take it up to non magnetic and let it cool in some ash from the fire.

However if i had to guess the steel i would say L6 but its still a crap shoot.
 
The majority of those old blades test out at .80% carbon and 2% nickel.....basically 1080 with 2% nickel. That has a HT similar to 15N20.

Use the generic HT for unknown carbon steel:
Austenitize at 1500F and soak for 5 minutes.
Quench in medium oil ( canola will do fine)
Temper twice at 400F for two hours each.
 
Would i be right to assume that "Austenitize at 1500F and soak for 5 minutes." just means to bring up to 1500 and keep it there for 5 min?
 
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