Hardening / Tempering 1095 Questions

[ThomasPowers]

My Daughter the Veterinarian worked in Roswell for a while...

[Frosty]

I'm pretty sure we're not talking about the same gal. 

I've been through Roswell one time on a family vacation with the folks. I don't recall if we were near Roswell at the time but while in NM Dad probed a small critter dashing across the highway with a fast moving Chevy. . .  We were in the Chevy, not the critter.

Frosty The Lucky.

[Jimw3326]

I had 3 blowouts on my way to Roswell one trip. After the third I had to push a flat with me down the highway until a stoner gave me a lift.

[anvil]

What Jason L said above. Lol, old outhouses aren't filled with boulders or rocks.  Proper tool for a proper tool.    

[patrick]

On 4/28/2023 at 9:20 AM, BillyBones said:

To your original question, from the way i read it you want to harden a piece of steel but leave it hot enough so that the residual heat from the steel will temper it. I do not think that will work.

The original poster raised the question of doing a short quench and letting the residual heat in the piece effectively temper the part. I agree that this would not give quite the expected result, but such processes are actually quite widely used, especially with steels that have higher hardenabilty than 1095. The is a process, known as austempering, in  which the steel is rapidly cooled to some temperature below the pearlite formation temperature but above the martensite formation temperature. For example 600 F. If you rapidly cool to 600 F, you will avoid forming pearlite. By holding at 600 F for an extended period and then cooling to room temperature, the structure formed is bainite. When formed at relatively low temperautre, bainite is quite hard, some times in excess of HRc 50, and can be so tough that no further tempering step is needed. A similar effect can be achieve by quenching in water or oil or polymer solutions for a fixed time to remove most of the heat from the part and then let the residual heat "hold" the part at the desired temperature above the martensite temperature until the part has naturally cooled to room temperature. These kinds of practices are use by at least one sword maker I know. Similar approaches used to be common place with commercial knive and sword makers. They would sometimes quench in molten lead. Today, various molten salts are used to achieve similar effects. 

In the example from the original poster, I think the bar is so small that these practices are not practical, but pulling a part out of a quench bath while it still has residual heat in it is a common practice in industrial heat treatment.

Edited June 16, 2023 by Mod30
Trim quote.

[Irondragon Forge ClayWorks]

It's also a common practice with a lot of blacksmith's myself included. My master Ike Doss used that technique and taught it to me.

I can't control the wind, all I can do is adjust my sails. ~ Semper Paratus

[anvil]

I use the reserve heat type of tempering, or differential tempering on nearly all my ht. The heat runs from the eye to the face on a hammer, the shaft to the edge on a chisel and the spine to the edge on a knife. However, as I read the OP, he is quenching the outside of a ~1/4" round 3' long and wanting the heat in the center all along the length to run out ~1/8"  to the outside edges, to get a spring temper along the 3' length. Not going to happen.  

[Frosty]

It works better for some things than others, the thinner the section you're treating the more difficult and prone to poor results or failure. Using this techniques on knife blades is pretty advanced. 

Frosty The Lucky.

[anvil]

Never looked at it that way. Its just a way that has a bunch of positives and no negatives. Doing chisels is a no brainer. Bring about 1-1/2" of the end up to critical, or after it loses its magnetism, quench about 1/2" - 3/4" and give it a quick buff and watch the colors run. Put it tip down in a tin can with about an inch of water in it and let it cool. Then you go from normalized to a nice color run. After you've done this a few times, do a knife. Same technique, just a different shape.    

Also its pretty bullet proof for healing mistakes whilst learning. About all you can do is miss your temper color. If so, just anneal and repeat the above. Time spent equals learning

[Irondragon Forge ClayWorks]

I use a common red building brick to shine up the area that I want to watch the color run. That trick was shown to me by Bob Patrick at a club meeting.

I can't control the wind, all I can do is adjust my sails. ~ Semper Paratus