At some point most of us will pick up or inherit a bar of mystery steel from another knifemaker. I'll outline my process for figuring out what it is, and then ask for some help on a particular bar.
First I spark test it, just because it gives me a referece point.
Second I do 1500 x 10 minute soak, quench in 10 second oil.
If that doesn't work, I do 1550 x 10, then oil.
If that doesn't work, I do 1950 x 30 then plate quench.
I also include a scrap test piece at each step, so I can break it and check the grain.
This testing procedure works reasonably well, especially if you have a hardness tester. Once you get an as quenched of 60 or greater, you can walk then tempering temperature up to get the hardness to 59 or so.
This brings me to my present bar of mystery steel. It came from the now deceased knife maker unmarked with a knife scribed on the bar. Unfortunately I didn't have access to my RC tester for this one. It doesn't throw much spark, and the sparks aren't "fuzzy" like a straight carbon steel. I sparked it next to CM154 and it was somewhat similar. Tried to flash rust it, and only got a few specks.
Both oil quenches resulted in insufficient hardness with brittleness and fine grain.
Air quench resulted in better hardness. A test piece broke cleanly. I sharpened the test piece and was able to get it to hold an edge under chopping conditions, but the edge was admittedly thick prior to sharpening. As far as polishing, this steel in this state was a major PITA to polish. Seemed very abrasion resistant. No alloy banding or orange peel, etc.
The most interesting part of this particular one: the steel lost its magnetism after HT/plate quench. Prior to HT, the steel stuck to my magnet with good strength. After HT, it barely sticks at all.
Based on these observations and tests, what do you think I have?
First I spark test it, just because it gives me a referece point.
Second I do 1500 x 10 minute soak, quench in 10 second oil.
If that doesn't work, I do 1550 x 10, then oil.
If that doesn't work, I do 1950 x 30 then plate quench.
I also include a scrap test piece at each step, so I can break it and check the grain.
This testing procedure works reasonably well, especially if you have a hardness tester. Once you get an as quenched of 60 or greater, you can walk then tempering temperature up to get the hardness to 59 or so.
This brings me to my present bar of mystery steel. It came from the now deceased knife maker unmarked with a knife scribed on the bar. Unfortunately I didn't have access to my RC tester for this one. It doesn't throw much spark, and the sparks aren't "fuzzy" like a straight carbon steel. I sparked it next to CM154 and it was somewhat similar. Tried to flash rust it, and only got a few specks.
Both oil quenches resulted in insufficient hardness with brittleness and fine grain.
Air quench resulted in better hardness. A test piece broke cleanly. I sharpened the test piece and was able to get it to hold an edge under chopping conditions, but the edge was admittedly thick prior to sharpening. As far as polishing, this steel in this state was a major PITA to polish. Seemed very abrasion resistant. No alloy banding or orange peel, etc.
The most interesting part of this particular one: the steel lost its magnetism after HT/plate quench. Prior to HT, the steel stuck to my magnet with good strength. After HT, it barely sticks at all.
Based on these observations and tests, what do you think I have?
I had that part figured out. Any input on the magnetism thing? That part was unexpected, at least to me.