Tempering Quenching Annealing

I would like to talk a bit about tempering steel. This post is going to be very broad and as simple as I can make it without going into great detail. There are almost as many kinds of steel and iron flavors as fans at a baseball game. I generally re-purpose steel that I find. If you know you specific flavor of steel you can research the proper tempering method for it.
This subject has books written on it. This is just a crash course for simple tool making.
The three topics I want to discuss are, annealing, quenching and tempering.

Annealing is a heat treatment that alters a material to increase its ductility and to make it more workable. It involves heating material to above its critical temperature, maintaining a suitable temperature, and then cooling. Annealing can induce ductility, soften material, relieve internal stresses, refine the structure by making it homogeneous, and improve cold working properties.

Quenching is the rapid cooling of a workpiece to obtain certain material properties. It prevents low-temperature processes, such as phase transformations, from occurring by only providing a narrow window of time in which the reaction is both thermodynamically favorable and kinetically accessible. For instance, it can reduce crystallinity and thereby increase toughness of both alloys and plastics (produced through polymerization).

Quenching Rate: (FASTEST) Salt water > water > oil > air. (SLOWEST)

Tempering is a process of heat treating, which is used to increase the toughness of iron-based alloys. It is also a technique used to increase the toughness of glass. For metals, tempering is usually performed after hardening, to reduce some of the excess hardness, and is done by heating the metal to a much lower temperature than was used for hardening. The exact temperature determines the amount of hardness removed, and depends on both the specific composition of the alloy and on the desired properties in the finished product. For instance, very hard tools are often tempered at low temperatures, while springs are tempered to much higher temperatures.

Now some reference pictures.
tempercolors2TemperColors3TemperColorsFeC_diagram
With all that I get in a bit more depth in my video. This just skims the subject.

Resources
http://www.threeplanes.net/toolsteel.html

http://www.gowelding.com/met/carbon.htm

http://ajh-knives.com/metals.html
Please friends ask questions, that is how I learn.

Please be careful. Some of the things I do are dangerous. It is not my fault if you get hurt. Use your brain, be safe.

10 Responses to Tempering Quenching Annealing

  1. Very good info Dave.

  2. roger says:

    thnx Dave. Lotsa gr8 info there.

  3. DIYaholic says:

    That was interesting. So, you don’t need a forge to temper metal, it can be done with tourch or oven. That is good to know.

    If I have this rigt, the forge is for annealing so you can manipulate/shape the metal, then quench it. File/sand to final shape, then temper with tourch/oven. Sounds so simple…
    Much more difficult in practice, I’m sure of!!!

    Thanks for taking the time to explain this. I hope someday to put it to use. However, I must first put my woodshop to use!!!

    • David Bardin says:

      Randy how ever you make the steel hot doesn’t matter. What I was trying to show is how you can temper the steel. So if you need a simple tool. Make it then temper it and your off and running. It can get complicated if you don’t know what type of metal you are dealing with. But with a bit of knowledge you can give it a good try.
      Its always good to have a trick or two in the bag. This information might get you out of a spot someday.
      You are more than welcome Randy. You asked me one time about it and I told you I would try to post something on it.
      You the man Pres.

  4. JL7 says:

    Good one Dave….I’m going to save my old files…..just in case……

    Seriously…you’ve leaned a lot about this craft……Keep on……..

    And btw….the notification system is broken, no email on this one…..

    • David Bardin says:

      Thanks Jeff. I am trying to get a handle on it. I want to make real tools one day.
      Thanks on the email. Now I have to remember where that is and how it is supposed to work.

      • JL7 says:

        Got a reply now…..:)

        • David Bardin says:

          Jeff I have spent the last hour looking for the part that notifies people when I post. I cant find it. I think an update removed the email notification. So I re-posted it again with no change to the site and it did not send. I then went and found a plugin to give me back the ability.Let me know if you start getting 2 emails on the post. Thanks for the heads up Mr mad scientist.

Forge a whitty reply.

%d bloggers like this: