Question on heat treating 1144 stressproof

[deepcreekdale]

Recently, I purchased a benchtop furnace from PMC which so far has worked perfectly and is handy as all get out. However, yesterday, while rooting around for some lock parts I ran across an old instruction sheet from Bud Siler. He mentioned not using a furnace for hardening as it would remove carbon from the steel due to lack of oxygen although they are fine for tempering. According to the manufacturer and various reviews on the furnace from machine shops and others, the furnace is fine for this purpose. Question for you metallurgists/machinists out there. Who is correct? I usually fabricate my parts from 1144 based on Bob Rollers recommendation and it is outstanding stuff to work. Is Bud's recommendation because he uses 4140 steel or what. I have not used my furnace yet to harden springs for which I use 1070/1075. Will an electric furnace work for this?

[Bsharp]

I think that you just use it the way it is, this is all I found.

"If you are using streeproof for it'd Elevated Temperature Drawn properties, the material cannot be heat treated, it will loose those properties.

The stuff is drawn through dies at about 350 degrees f. This gives it is's strength because of the working.

If the stuff is heated it reverts back to the strength of it's constituent alloy in the annealed state.":

[Bob Roller]

I think that you just use it the way it is, this is all I found.

"If you are using streeproof for it'd Elevated Temperature Drawn properties, the material cannot be heat treated, it will loose those properties.

The stuff is drawn through dies at about 350 degrees f. This gives it is's strength because of the working.

If the stuff is heated it reverts back to the strength of it's constituent alloy in the annealed state.":
[/quote

This is the first time I ever heard that it can't be heat treated and I have used it in lock tumblers for about 50 years and NO reported problems from here or in Europe.I use a direct flame from a Presto Lite torch and heat it to a bright orange and drop it into a can of light oil.Get it out after it cools and clean and polish it and the draw it to a light straw color and that's it.
Whether or not an electric furnace gets hot enough I don't know but I DO know what worked for me when I was making locks.
I have stated many times that 1144 machines like 12l14 or "Ledloy"and hardens like drill rod.
Bob Roller

[Bsharp]

Nice to know, Thanks!

[deepcreekdale]

Thanks Bob. I have been heat treating the way you have using a torch with great results. I certainly trust Bud Silers take on heat treating, but like you I have never heard that you can't use a furnace for heat treating. By the way this furnace can heat up to 2200 degrees if needed. Which, unless I decide to try and cast something, I shouldn't. It seems to have a very precise pyrometer, so I am extremely happy with the unit and the price was great. I agree that the 1144 machines and works beautifully, better than anything I have ever used. It cuts, files and polishes quickly and smoothly. I would think in its unhardened state it would be way too soft for any part subject to wear.

[Bob Roller]

You're right about it not being useful in the "as delivered". I have used a hardened and tempered sear against a finished but not yet hardened tumbler and then fire the lock a few times and that trick will quickly establish a good trigger pull or an easy release by a strike from a set trigger. I know my methods rank up there with the stone axe but success tells its own story and there is no substitute for long years of experience.
bob Roller

[Jim Kibler]

In an air furnace like yours, you will get scale if heating parts above 1000F.  With scale comes decarburization.  The depth will depend on the time spent and temperature.  More scale equates to more decarb.  For some parts, this is insignificant.  On gun parts, you don’t want to deal either scale or decarb.  You can use an anti-scale compound to prevent or at least minimize this.  With careful use a torch is often easier for hardening.  The flame can be adjusted to minimize decarb, and the time at temperature is so short, there is little chance for scale / decarb to form.

As a side note, we use a salt pot for hardening springs.  I don’t think there is any better method than this.  No decarb occurs, parts heat quickly and temperature control is fantastic.  Molten salts are corrosive, nasty and dangerous, though.  For us the benefits outweigh the drawbacks.

[JPK]

In useing my electric furnace I pack my parts in clean cast iron chips. To anneal parts the part is placed in a crucible with the iron chips all around. Before placing the cap on I put a small piece of paper in. Once up to temp the furnace is allowed to cool over night. The part will be gray with out any scale. Heat treating works the same but I often use wood charcoal and again no decarbing of the part. Keeping the air from the part is key. As others have said 1144 machines great and is heat treatable.

[kutter]

I have read,,but I am not any heat treating expert or anything near to that,, that when hand files were (are?) made of high carbon steel, they were heated with a  casehardening pack around them called a 'loaf'.
That so the very surface of the steel, would retain all of it's carbon and maximum hardness. Their thinking (knowledge?) was that the surface lost some carbon & hardness in the heating and quenching of the through-hardening steel they are made of.
Not quite what Bud Siler pointed to in his writing but maybe something like that was what he was concerned with.

***********

FWIW,, a very cheap and easy to use substance to keep heat scale off of small items being hardened is Boric Acid.

You can buy the stuff very cheaply at garden stores and even Walmart as an ant and roach killer in powder form.
The powder is what you want.

Mix the powdered Boric Acid with plain alcohol into a paste.
(You can probably use acetone as the liquid vehicle as well but I never have)

Take your finished polished part or small tool , attach to a wire,,and coat it with the paste.
Build up a 'shell' of the Boric Acid on the part and completely cover it.
The alcohol will evaporate quickly and the Boric Acid will dry and cling to the part forming the shell.
You can dip coat the part or carefully brush layers on.
Build up layers to make the covering or shell around the part.
 It goes fast as the alcohol evaporates.

When you have built up a suitible shell,,,light/ignite the shell with the part inside and any excess alcohol will burn/flash off.
This leaves the shell hard but very brittle. Handle carefully by the wire attached.

Holding by the wire you can heat the part & shell with a torch to bright red if you want to. The shell of Boric Acid will not shatter or let O2 in.

When ready to quench, drop the entire shell w/part inside wire attached into the oil or water.
The shell will shatter and detach. The part will be the  polish color you started with & no scale or temper colors.
Ready for tempering.

I use it a lot in making small engraving punches and stamps, and other small tools, small parts, etc.
Very clean, very quick.