Mystery steel ID?

jkf96a

Well-Known Member
Occasionally we 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?
 
Little to no spark leans toward stainless of some sort, but you probably already knew that. Real tests are available for as little as $50. If you are doing this and expect to get paid for it, I'd say it's worth it to send it out. After all the cutting of coupons, heating, quenching, testing, rinse and repeat, it hardly seems worth it to guess. If this is a hobby and you enjoy the mystery, have at it. From my perspective, I've never understood putting all that labor into a piece of steel, then the necessary comparisons to known samples, when one doesn't know what it is. But again, if you enjoy it, wear it out.
 
Thats pretty wierd , no magnatism ? sounds like some carbon was lost ? I have oil quench 440-c with good results . Never lost its magnetic properties .?
 
Good news/ bad news so far on this one. Once I got home I tested my coupon, only got 44 RC. If this were 440C and I did it 30 minutes at 1950 (too much time, too much heat), with no cryo, that would leave alot of retained austentite, would it not? Isn't austentite non-magnetic?

Me2, I get it, but overall disagree. I already had the oven hot from treating blades of known steel, so it wasn't much of a waste of time or energy. What happened to your scientist/experimental impluse? Sometimes I just like figuring stuff out, even though I have 50+ ft of known bar stock :)
 
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Yes you are correct. Austenite is a metallic, non-magnetic solid solution of carbon and iron that exists in steel above the critical temperature of 1333°F ( 723°C).
I could be 440 -C a good guess . Experimentation is always interesting for me , I constantly try new things . Its a great way to learn trial / error. I would heat 440 -c right in the forge until non magnetic and then quench in oil . I could get 56- 59 rc . Lots of makers say thats not possible !! They also used said you cant put a decent hamon on 5160 , But I did it ... trying different techniques is how discoveries are made
not by doing it the standard way . It could also be 440-a ?
 
Here's an update, a month and a half later. I finally got another batch of stainless blades ready for HT. I put the blade from this thread in at 1850 for 30 minutes and got 61 out of the quench. It's in the dry ice now, report in the morning. Maybe my 440C too much RA theory wasn't too far off. Either way, at 61 I'm in the ballpark for a usable knife now :)
 
My hunch here is that it might be ATS-34 Stainless which will give a few rust spots, Not as Stainless as 440C.

I also have oil quenched 440C & ATS-34 with good results.
The late Mr. Bob Loveless is the man that popularized ATS-34 into the world of Knives.

Laurence

www.rhinoknives.com
 
I'm betting it's not ATS34... I consistently get 61 or 62 plate quenched from 1950 with a soak on ATS34/154CM. Did 5 blades with that exact result tonight.
 
Like I said, if you're having fun, then have at it. The magnetism thing is a bit odd. I'd send it out just for that, since there's no way I'd be able to make a reasonable guess after seeing that happen.
 
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