Heat treating

[Tom Gralewicz]

I would like to heat treat a mild steel bar to discourage it from bending.  

Any suggestions?  Just the end foot would be enough.

[jeff mann]

If your steel is a low carbon steel, to increase its hardness you need to add carbon, so it sounds to me like you want to carbonize it. Carburizing basically soaks the steel in carbon and diffuses it into the body. You might want to run some tests but clickspring has a good vijeo on the topic. Maybe someone in the forging area could shed some light and help you with your task more. https://youtu.be/V_Mp1fNzIT8 

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On Sep 21, 2017, at 6:04 PM, Tom Gralewicz <m...@ieee.org> wrote:

I would like to heat treat a mild steel bar to discourage it from bending.  

Any suggestions?  Just the end foot would be enough.

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[whoz...@aol.com]

Is it round or flat? If it is flat, could you form a rib or a V shape. This would do a lot to stiffen it.
Tom Balestrieri

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On Thursday, September 21, 2017 Tom Gralewicz <m...@ieee.org> wrote:

I would like to heat treat a mild steel bar to discourage it from bending.  

Any suggestions?  Just the end foot would be enough.

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[Tom Gralewicz]

5/8 round axle

On Sep 21, 2017 7:54 PM, "whoztommy via milwaukeemakerspace" <milwaukee...@googlegroups.com> wrote:

Is it round or flat? If it is flat, could you form a rib or a V shape. This would do a lot to stiffen it.
Tom Balestrieri

Sent from AOL Mobile Mail

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On Thursday, September 21, 2017 Tom Gralewicz <m...@ieee.org> wrote:

I would like to heat treat a mild steel bar to discourage it from bending.  

Any suggestions?  Just the end foot would be enough.

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[whoz...@aol.com]

Don't quite know what to say. If it's a flexural stress, you may be able to use a cherry red type product. It will give you a shallow surface hardness. It may help to stiffen the mild steel. If it's rotational of tortional stress, you may want to use a pre heat treated 4140 or 4150.

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[Dan Jonke]

The right way to do this is to use a heat treat compound. you coat the steel in it and heat for a predetermined time, that will allow carbon atoms in the compound to diffuse into the steel. You have to wrap it airtight in stainless foil to keep oxygen from burning out the carbon while its working. It's like the reverse of a soda going flat. But there are quick and dirty options as well.

 

Do you know exactly what alloy the bar is? Depending on how little carbon is in it, it may still be possible to harden using what they call "super quench"

 

The trick to hardening steel is to cool it really fast. The less carbon in the steel, the faster you need to cool it to get a harden. Usually the fastest way is with a tank of plain water, that doesn't really do anything to mild steel, which is usually in the 0.15-0.3% carbon range. but if you add a bunch of dish soap and salt to the water, you alter the boiling physics and can improve the cooling rates something like 50% beyond straight water. I'm told that its possible to get a harden on even some mild stuff. Never tried it myself.

 

The other thing you can do, is just leave the bar cooking in a slow burning coal forge for 20-30 minutes. There's so much carbon monoxide in that fire, that it will act like the hardening compound and add carbon to your steel, more the longer it stays in there. No need for special compound and foil. I have accidently shattered mild bars that way.

 

On the other hand, if you've got $6.52:

 

Tom is right, just buy a foot of 4140: http://www.speedymetals.com/pc-67-8327-42r625.aspx It's got chromium and molybdenum as well as carbon. Will be way more tough and hard at the same time. Beyond anything a case harden will get you.

 

-Dan

From: whoztommy via milwaukeemakerspace

Sent: Thursday, September 21, 2017 8:52 PM

To: m...@ieee.org ; milwaukee...@googlegroups.com

Subject: RE: [MakerSpace] Heat treating

 

[whoz...@aol.com]

Nice explanation Dan. There is no substitute for the right steel for the job. A good rod to use, if you want a good fit, is 1045 ground and polished stock. It is still machinable, keyways or flats, but is very tough and very straight. Thompson rod will also work well, but is case hardened.

Tom Balestrieri

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