Can I "un-harden" a piece of steel

srmofo · Apr 23, 2014

Actually Im not really sure what type of steel it is, but I ran across a large round disc of steel at a local salvage company called mendelsons.(3 floors of all types of junk, but thats another story)When I found the disc it was covered in years of filth, when I got it home and cleaned it off I discovered it was some type of master die for something. Uh-oh Im not gonna be able to drill holes in that.

Anyway I need to drill a few holes in it and I plan on welding to it as well. Is there any chance in hell that heat will soften this back up into something "machinable". I have a oxy torch if it needs more heat than welding will supply

Someone had etched an inspection date on it 6/2/82. I think I know where the years of filth came from. Its probably been sitting on that shelf for a better part of 2 possibly 3 decades

Also out of curiosity, anyone have any idea what this might have been used for?

dr_clyde · Apr 23, 2014

Short answer, yes you can un-harden steel.

Long answer, it'll take more work than you probably want to do. You're looking for something called a "full anneal". It'll need to be heated to above the upper critical temperature, which varies depending on carbon content, held for an hour, then cooled very slowly. This allows the hard martensite to fully transform into austenite, then as it cools slowly, ferrite is formed instead.

You may get lucky and be able to spot anneal with your torch, but you may end up doing more harm then good.

What are you making?

Trucky · Apr 23, 2014

Call a heat treat place nearby and tell em to roast it til it's soft.

also, if you want to know what it was used for, a full picture of both sides/ends might help.

metaleltr · Apr 23, 2014

What about having it lasered or water jetted, i know there should be a few places within 20 minutes of mendelsens that could do it

Rory Bellows · Apr 23, 2014

You can drill it with an ordinary masonry bit (carbide spade) or you can buy a cheap solid carbide bit off ebay.

yaidunno · Apr 24, 2014

If those numbers were stamped in after treatment, you should be good to go. Of course they could have been stamped before hand as well. I'd do a spark test, or run an old file on the edge. If you have access to a hardness tester, that would be better yet.

Something tells me you wont get 6.5" slug to annealing temps at home.

theknurl · Apr 24, 2014

dumb question......

what are you trying to build?

Don Quixote......wasn't very successful

:lol_hitti

zkling · Apr 24, 2014

Looks like some type of reference gauge, for what :dunno:

. Test it with a file real quick, see if it grabs or skates. It's most likely a piece of high carbon tool steel. Meaning welding will be a sketchy operation and lead to brittleness in the surrounding zone. A good soak below critical and slow cool back to room temp would probably do the trick. Depending on how crazy you want to get with the project a large furnace would be nice. Otherwise the torch a rosebud, a temp stick and some insulating blanket would probably get you there. I've heard alot about mendlesons, but never been.

You could do it only in the spots you want to drill but you may get some movement and warping in the piece. If you know anyone with access to a wire or even sinker edm, that would solve your how to hole problem.

Kevin54 · Apr 29, 2014

Mofo....If you haven't tried to drill it yet, give it a shot, or hit it with a file. Just because it's a Master Tool doesn't necessarily mean it's been hardened.

If it is hard, if I remember correctly, you have a mill. Clamp it up on a piece of wood and go at it with either a carbide endmill, or a carbide drill.

WHere I worked, we had thousands of masters, and some of them were made out of epoxy. THey were just used for a fit check and nothing else, and Masters are usually stored in special rooms where not just anyone can get to them and damage them.

Then again, you may have something that is harder than Kelsey's Nuts!!!!

BTW.....Is it worth the trip to Mendelsons? I spent a few hours the other day online looking at some stuff, but is it worth it to go through the place?

skyking · Apr 29, 2014

My wife has been doing it for me for years .......... :spit:

1grnlwn · Apr 29, 2014

I wonder if you could throw it in a nice hedge fire for a few hours.

Kevin54 · Apr 29, 2014

1grnlwn said:
I wonder if you could throw it in a nice hedge fire for a few hours.

It all depends on what type of metal it is. If it is air hardening, you heat it up red hot again, then let it air cool, it will be glass hard and brittle as a potato chip. To anneal a lot of heat treated materials, you have to get them up to temperature then cools slowly. Years back, we used to bury a part in sand to slowly cool.

srmofo · Apr 29, 2014

Kevin54 said:
Mofo....If you haven't tried to drill it yet, give it a shot, or hit it with a file. Just because it's a Master Tool doesn't necessarily mean it's been hardened.

If it is hard, if I remember correctly, you have a mill. Clamp it up on a piece of wood and go at it with either a carbide endmill, or a carbide drill.

WHere I worked, we had thousands of masters, and some of them were made out of epoxy. THey were just used for a fit check and nothing else, and Masters are usually stored in special rooms where not just anyone can get to them and damage them.

Then again, you may have something that is harder than Kelsey's Nuts!!!!

BTW.....Is it worth the trip to Mendelsons? I spent a few hours the other day online looking at some stuff, but is it worth it to go through the place?

Well, the file wouldnt even scratch the surface

so back to the drawing board. I just need a round piece of steel to make a flywheel of sorts to give a little mass to the pulley. Im trying to stay low buck so any professional procedures are out. I was at mendelsons picking up a few other things and just stumbled upon it. No big deal, no money lost on it.

Next time Im at the scrap yard Ill pick up a round blank. They always seem to have piles of them laying around in all various sizes. This one just appeared to be perfectly round already with the hole in the center.

Kevin, Mendelsons is worth the trip if you like digging around in a dingy dark warehouse for miscellaneous ****. Make sure you have a few hours to kill, clothes you dont mind getting dirty, a few bucks, and a few projects in mind. Also, the flea market **** is on the first floor along with all the commercial kitchen stuff. Skip it and head straight to the third floor. That's where all the good stuff is.

Their internet listings are a joke

Kevin54 · Apr 29, 2014

It sounds like you have a hard piece of material for certain. What type....it's hard to tell without sending it to a metallurgical place to analyze it. Carbide drill or endmill should work unless it is some rare alloy. I know that I've had to modify parts before sing carbide, but when the parts are really hard, you'll trash the endmill or drill.

Do you have a plasma cutter? If you do, you shouldn't have any problem. The only thing you'd have to do is grind the slag off.

Can I "un-harden" a piece of steel

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