A question on the difference between normalizing and annealing when making a knife.

My understanding from reading an artical by Ed Caffrey is that Normalizing is heating a blade to non magnetic and allowing it to cool to room temp while setting in a draft free area. This is to allow the internal stress to relax in the metal.
Annealing is heating to non magnetic and then placing the blade in a well insolated materal so the blade cools very slowly. This reduces grain size of the steel.

My question is would not annealing do the same thing as normalizing? I am not understanding why you need to do both. Thank you for any help in my understanding of this confussing (to me anyway) subject.
William

I am lousy with names and terms, I am bad about using less than correct terminology. so I will be careful here.

After normalizing I check to make sure the blade is straight, some times it curves, or even cork screws if it was not hammered evenly. Especially when twisted cores in my pattern welded blades.

when all is normalized, and I am sure it straight I will then anneal, ( it IS a second normalizing in the sense of relaxing the stress that may have gotten missed the first time, some do this 3x, I don't feel its worth it for three times)

yes the grains grows a little bit, but that will not be a problem, as another normalizing cycle comes after grinding, and before the hardening. Annealing mainly makes the steel easier to work.

so Yes annealing IS going to relax the steel Just as normalizing.

Since writing that, I have learned more, and have modified the way I do it. The method your speaking of works, but what I do now works better. Maybe the term "thermal cycling" might be more representative than "Normalizing". Anyway, heres what I now do, and am teaching to my students....

After you've completed forging, bring the steel to 1200-1300F, which in most cases, depending on your ambient light, will be a very dull blood red. Then allow the steel to cool in still air to below 800F. This is what I refer to as my "insurance policy" because doing so will heal any grain growth that occurred. In addition, it is also stress relieving the steel. I perform this cycle 3X, then go to non-magnetic for the annealing heat, and place the steel in vermiculite.

Its basically doing the same things that I previously described, but just "better". Spectrographs have shown that the steel is achieving smaller grain size than most other methods I've had tested.

I also perform the "thermal cycling" just prior to hardening a blade, and as with the other method, it will usually eliminate any warpage.

To directly answer your question....Annealing will relieve stresses, but sometimes not all of the stress....and often times this will lead to warpage later on in the process. In my opinion, stress relieving steps are a must, and if you choose not to perform them, you may not experience probelms, but on the other hand you might......I would rather err on the side of caution, than fret about it after something has gone south.

Thank you Ed I do appreaciate you time in answering my question. I will start to add this step to my work. You also took some time to give me some suggestions on making a tomahowk a few months ago and I did post a picture of it this section titled "some of my work" Thank you again for your willingness to help

Thanks Ed,
I've been hangin out with MS Wally Hayes and that's the method he taught me as well.... haven't had any warpage (knock on iron) since I've adopted this process.

Rick

If I may offer more explanation on annealing vs normalizing. Annealing involves heating a steel for the purpose of SOFTENING it. You will find that different steels involve different temperatures. Heating to 1350-1450F and very slowly cooling it will soften most steels without much grain growth. Heating to 1650F and slow cooling may soften it more but may result in larger grains, which generally are a bit more brittle. Normalizing is intended to homogenize the grain size after forging or welding. It will also stress relieve if cooled slowly. Large grains promote deeper hardening when you quench it so it is important that all the grains be about the same size or you get non-uniform hardening and possibly warping. Normalizing a high carbon steel can make it harder. The higher the normalizing temperature, the more you risk grain growth. The longer you hold it at a high temperature, the more the grains grow. If you normalize several times, try to do it a a lower temperature each time. This will reduce the grain size and improve toughness. I posted a blueprint several years ago on Basic Metallurgy for Blacksmiths but I can't find it anymore with all the changes to this site. Maybe Glenn can post a link.

Edited July 4, 200817 yr by Quenchcrack

BP0078 The Metallurgy of Heat Treating

I just learn a heck of alot in this thread...I appreciate it. Thanks....

Glenn,

 

   Can you get the link posted on this thread fixed, I would like to read it.

 

Thank you

Russell

try this  http://www.iforgeiron.com/index2.html/blueprints/original-series/bp0078-the-metallurgy-of-heat-treating-for-blac-r306/

 

this was covered in the pinned heat treat sticky to, if you take the time to read it.