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Tempering metal ?

Posted by gonefishin (My Page) on
Tue, Oct 5, 04 at 10:22

A question of those that know. I plan to twist a piece of 1/2" X 2" flat strap stock 90 degrees only, by heating it with a torch and twisting. I want it to retain its strength, yet be able to drill a hole or two in it if need be.
To retain the strength of the metal, should I let it cool naturally, plunge it into water ? oil ? .

How does all that work ?
Thanks in advance.
Bill P.


Follow-Up Postings:

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RE: Tempering metal ?

Steel needs carbon to make it hard with heat treating. If this is hot roll or cold roll steel it does not have enough carbon to make it hard. Just heat with torch and let it cool by itself. It can be cooled in water after the red color is gone.


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RE: Tempering metal ?

If its not a carbon steel, you can crush a carbon rod out of the inside of a D-cell battery and wrap you'r metal in foil with the crushed carbon and you will have case hardened if heated to red heat and let cool...


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RE: Tempering metal ?

Thanks guys, I do really appreciate it. I got it done, by clamping a big piece of I beam to the workbench, then clamping the bar to the I beam. It took longer than I figured to get that half inch X 2" bar red hot, then I had to put a piece of pipe for a cheater on the big pipe wrench. It may be just a tiny hair off 90 degrees, but close enough for govt. work as they say. I wound up with a slight drop on the short end of the bar from bearing down on the pipe wrench, but that "accident" will work out perfectly for what I am going to use it for. That size bar is pretty strong stuff and should be more than adequate for any application connected with a Garden tractor implement, outside of something truely extreme which is not in my plans. I will post some pics in a day or two of how it turns out.
I just did not want to weaken the metal, nor to make it too hard to drill and was not sure about changing any temperment of the metal.
What you guys responded with is appreciated and it is good to know., Thanks.
Bill P.


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RE: Tempering metal ?

O.K. as promised, here is that twisted bar. What is it for?

Hooked up to middle buster / bedder, looks like it should work well, plenty of range of motion and multiple adjustments on plow to set the plane so it can do its job right.

Hung out to dry:


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RE: Tempering metal ?

Looks nice!

Also looks like mild steel, so like they said, no need to worry about its losing its hardness... it didn't have any to begin with. If it breaks, just make it out of a thicker chunk next time...

You probably don't want to case harden it - all that would do would give it a harder outer shell, but the bulk of the piece would still be the same hardness as what you started with. Since its purpose is to bear a tensile load, no need for a hard surface. Just my opine.


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RE: Tempering metal ?

Thanks Rich, I appreciate the opine. It seems to be plenty strong for my needs, I took the plow off and used the hitch part with a reavy rear blade that I bolted on thru those two bolt holes there. It handles that alright.
I also appreciate your good info in the resonse about machining steel rod. That however, is for an entirely different application, steel guitar slide bars. There is so much about them that I do not know, being pretty much of an amatuer in that field, just kinda stumbled into the possibility of making some for a guy that is somewhat famous for the ones that he markets around the world via a website and ebay, but mostly from noted players word of mouth comments on their forums and that type of stuff. He has been getting them made way too cheaply then doing his "thing" to them to make them unique and consequently his signature stuff, but his supplier is retiring so he is looking for another source. Since I am a customer, he mentioned it to me. In the conversation, he mentioned some tapered ones, and the thing about freezing stainless for 7 days to make it harder so that the wound steel strings would not cut grooves in it as easily with prolonged use. The surface would be what is important on that, not the tensile strength. The powdercoated ones are probably going to wind up with grooves anyway if they are used on the wound steel strings for quite a while. Heck, I might be better off with one with grooves in it than I would with one that is real slick.
I do appreciate it.
Bill P.


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RE: Tempering metal ?

Hmmm. I'll have to research the frozend SS hardening a bit more.

Somehow I dimly recall hearing about hardening steel in liquid nitrogen. I will have to look into this some more.

I can see how steel guitar strings could wear away a metal slide. On the one hand you want the slide to last. On the other hand you may not want it so hard that it wears out the strings...


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RE: Tempering metal ?

Thanks for jogging my memory. I recall that some heat hardneable stainless steels can be further hardened by cryogenic treatment. I believe there are some types of kitchen knives that claim to use this process. However from what I can gather it's a tricky and not entirely reproducible process.

I put more information in your machining rods thread. If you can find a copy of the Machinery Handbook, there's more inforamtion there, as well, about cryogenic treatment of steel.


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