Heat treating tool steel

B

Bill DeShivs

New member
Here are some tips on heat treating tool steel (1095 and 01)-
One of the major misconceptions about heat treating concerns tempering. The steel must be fully hardened and THEN tempered to the proper hardness.
This is the only way to harden/temper steel:
First the steel must be heated to glowing red. While the part is still red, quench it in light oil (I use canola oil). The steel should be glass-hard. A file should not cut it. The file should slide off the metal. If the part is not fully hardened, you MUST repeat the first step.
Polish off the carbon buildup so that you can see bright metal.
The next step is tempering.
Most parts such as firing pins should be tempered to "spring hardness."
Heat the part very gently until it turns bright blue. Immediately after the blue color comes a dull blue-grey. Remove the heat at the blue-grey color.
If you go past blue-grey the part may be too soft.
Practice on a few pieces of scrap steel before you attempt heat-treating a part.
Remember- steel has to be fully hardened, and THEN drawn back. It won't work any other way.
 
Light oil dissipates the heat rapidly, but not so rapidly that the part will warp.
One quench is all you need. There is no need to quench when annealing-just let the part air cool.
 
I've read salt water brine works well for quenching too.

Bill, do you ever work with salts (such as nitre salts)? I find metal smithing interesting and I have done some reading on the subject, but I have never actually applied that knowledge. I do have some projects that I will eventually get around to doing. I need to learn to weld too.

Neat Topic.
 
Water works well, as does brine. The problem is that it works too well. It quenches too quickly and the part can warp. This is not an issue for stout parts but, thin parts are more critical.
Canola oil does not smoke much and doesn't stink.
I have no experience with nitre salts, and I need to learn to weld, too!
Hard soldering (silver brazing) has done all I have needed so far, but welding would be handy.
I don't do much gun work these days-mostly cutlery restoration and knifemaking.
 
Nothin' is more attractive on a custom knife than a healthy temper line. At least in my eye. A filed spine looks nice too. I'd like to make a custom quarter rib for my Ruger #1 and file a "vine" across the top. A nitre blued buttplate would be my next step in this custom. Custom knife making has many applications that could be used in gun making. Too bad they are not carrying over.

View12.jpg


Rspike2.jpg
 
Fisherman
I have actually fileworked NAA mini revolvers. A fileworked rib is a novel idea.
I use heat bluing frequently on screws and small parts.
Some of my work is shown on my web site.
 
Bill, olive oil works pretty good for 01 and 1095, too. It's what I use when I make my knives. I'll have to give the Canola a whirl, I know it's cheaper.

Jason
 
I have made several knives over the years using an old BBQ Hibachi as the fire pit and an old vacuum cleaner as a blower. My quench media was old motor oil. Made some "terrible" blades out of old files and leaf springs. Gotta work outside using the old oil lots of acrid smoke. For knife blades I alwas tempered to the straw stage.
 
Motor oil works fine, but it smokes a lot, stinks, and can flare up.
Canola oil does none of the above. Use what you have in a pinch, but if you have to buy something, go with canola oil.
 
heat treating

Hey! Bill!
I'm going to try some Canola oil - sounds capital!
Harry B.

That steel sure has enough "points" of carbon to harden good - I'll really try canold oil - I used to use room temp water with a skim of oil on top to do the same thing or run pins in the drill press and go "endo" on the quench - I know you comprehend.
 
Last edited:
There are two old watchmaker/gunsmith methods of tempering the steel after hardening that offer MUCH better control than other home methods.

One is the lead bath method.
For this one you melt a pot of lead in a bullet casters furnace or in a large pot for bigger objects.
Once the lead temperature has stabilized, simply drop the hardened and polished steel part in the lead, and HOLD IT UNDER with a long wire or tongs.
Steel will float on the heavier lead so you have to hold it under the surface with one corner sticking up.

Watch the steel as it changes color, and when it's the color you want, pull it out and quench in water.

The second method is the sand bath method.

For this one, wash some sand until it's clean of dirt and dry then fill a deep cookie pan or baking pan with the clean, dry sand.
Put it on a stove burner and heat the sand up hot.
Drop the part in the sand and bury it with just a corner sticking out.
When it turns the right color, pull out and quench.

These methods work well because the lead or sand heats the metal uniformly and it all tempers the same amount.
Since you can watch the colors change very easily, it's possible to get very uniform results.
When tempering complicated thick/thin parts the entire part is the same temper and color.

This is particularly good when color tempering Luger parts where you not only want the part properly tempered, you want it to have the right color.

There's also an old watchmakers trick for heat bluing screws.
Make up a small "pancake flipper" from thin sheet steel with a handle.
Drill holes in the flipper that will allow you to drop screws in with the heads flush.

Constantly moving the flipper over a flame, watch the screw heads as the heat causes them to turn color.
When the screws are a bright blue, remove from the flame and quench.
 
You must log in or register to reply here.
Back
Top