Darrin Sanders
Moderator
Ok folks, I thought I'd kick this off with a few words about scrap/mystery steel? Can you make a good knife from mystery steel? Of course you can. Can you waste a lot of time and consumables and end up with a knife that is not worth the effort? You bet. By its very nature, we can't keep mystery steels totally fact based but I will try my best. Here is my opinion on the best ways to handle mystery steel. Please remember that this is just my OPINION but I hope most people will agree.
If you have a large amount of said steel and you're sure its all the same, your best bet is to find a company to test it and give you the chemistry. This will give you a much better idea of whether or not it will make a good blade and also some ideas of how to heat treat it. Use your Google-Fu to find someone in your area who can/will test it, find out what size they need for the sample, & go from there. Once you have the chemistry and you're fairly certain that it will make good knives then start working up a heat treat recipe through trial & error.
If you have some scrap steel but not enough to justify the cost of a chemical analysis then the best thing to do is harden a small blade sized piece and break it. If it snaps like a piece of glass and has a small grain structure then it might make a decent knife. The next step is to make a test blade, heat treat it, & test it. You may have to adjust hardening temps. & times in order to get the best hardness out of the quench. You'll almost definitely have to play with the tempering temps. in order to find the "sweet spot".
I also want to add that its commonly believed that files are 1095, W1, or W2, saw blades are L6, bandsaw blades are 15N20, & automobile springs are 5160. Sometimes this is the case but often it is not.
Spark testing will tell you a lot about the carbon content in a steel. Steel with enough Carbon will make a complex or "forked" spark when grinding it. If you don't have any experience in doing a spark test, you can look at the sparks from a known steel and compare them to the sparks of your mystery steel.
Some people hate the thought of mystery steel but many people love making something useful from a piece of "junk". People also enjoy the trial & error process of getting the most out of something unknown. If thats what floats your boat, by all means, go for it & have fun.
If any of you feel that I've left out something important on this subject then by all means let me know.
If you have a large amount of said steel and you're sure its all the same, your best bet is to find a company to test it and give you the chemistry. This will give you a much better idea of whether or not it will make a good blade and also some ideas of how to heat treat it. Use your Google-Fu to find someone in your area who can/will test it, find out what size they need for the sample, & go from there. Once you have the chemistry and you're fairly certain that it will make good knives then start working up a heat treat recipe through trial & error.
If you have some scrap steel but not enough to justify the cost of a chemical analysis then the best thing to do is harden a small blade sized piece and break it. If it snaps like a piece of glass and has a small grain structure then it might make a decent knife. The next step is to make a test blade, heat treat it, & test it. You may have to adjust hardening temps. & times in order to get the best hardness out of the quench. You'll almost definitely have to play with the tempering temps. in order to find the "sweet spot".
I also want to add that its commonly believed that files are 1095, W1, or W2, saw blades are L6, bandsaw blades are 15N20, & automobile springs are 5160. Sometimes this is the case but often it is not.
Spark testing will tell you a lot about the carbon content in a steel. Steel with enough Carbon will make a complex or "forked" spark when grinding it. If you don't have any experience in doing a spark test, you can look at the sparks from a known steel and compare them to the sparks of your mystery steel.
Some people hate the thought of mystery steel but many people love making something useful from a piece of "junk". People also enjoy the trial & error process of getting the most out of something unknown. If thats what floats your boat, by all means, go for it & have fun.
If any of you feel that I've left out something important on this subject then by all means let me know.