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P.Abrera

Normalizing/Anealling

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Does one have to heat up to a non-magnetic temp to normalize or will a general red heat yield the same effects?

 

Addtionally, I'm finding it hard to reach a consistent non-magnetic temp across the whole blade at one time in my forge. By the time one spot gets to non-mag and I move the blade to get the rest of it to non-mag temp, the previously non-mag section is steadily dropping in temp. Will I get an "even" normalization if I'm in effect heating in sections?

 

P. Abrera

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How do you plan to heat treat whilts having a problem getting even temperature to normalize? Perhaps it is time to build a forge suitable of an even heat. What are you using for a forge?

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<font color='#000000'>How do you plan to heat treat whilts having a problem getting even temperature to normalize? Perhaps it is time to build a forge suitable of an even heat. What are you using for a forge?</font>

<font color='#000000'>I guess I'm crossing bridges as I get there in terms of solving problems with regards to my set-up. Im first-timing on a simple japanese-style forge (burning charcoal in a canal formed from 2 parallel rows of concrete brick with a 2-inch tuyere coming in from one side with an electric blower supplying the air). I can get a pretty intense heat going but sweet-spot is centered by the tuyere. I've been putting-off modifying the forge to a set-up more like the one's on the tim lively site (tuyere running lengthwise with multiple "blower holes" drilled along its length) which looks like it could give a more even heat across the length of the blade at one time.

 

But after some more research I think I can solve my dillema simply with better technique. Keeping the blade in constant play over the fire/coals so that I'm gradually building an even heat (wether normalizing or in heat treating) over the entire length of the blade rather than one spot at a time should yeild better results.

 

...But does "normalization" happen at heats less than non-mag?

I'm using Hrisoulas' book as my reference and he talks about normalization as just heating to a dull red and leaving to cool in still air. But other references talk about heating to non-magnetic, which is hotter than just a dull red, in my (limited) experience. Is there a definitive answer?</font>

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The answer depends on the steel and what you're trying to do to it. The metallurgists definition of normalizing is to heat about 100F above critical temperature and air cool.This is done to produce a uniform structure and refine grain.However if this is done with an air hardening steel it will harden .Therefore you can't normalize air hardening steel , it must be annealed [Heat 100F above critical and slow cool in ashes or in the furnace].Using nonmagnetic as the temperature is fine. YES by all means heat the entire blade uniformly, much better !

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I suspect that Hrisoulas can judge the critical temperature of the steels that he works with by eye. The colour that the steel looks when it is at critical temperature varies from steel to steel and is also affected by how much ambient light there is (there are probably many more factors).

 

A good way to judge at what temperature the steel should be quenched is to watch for decalescence, as this shows when the steel is changing phase.

 

http://www.dfoggknives.com/hardening.htm :)

Edited by Christopher Barry

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The idea that normalizing means to heat the steel just above critical temperature and then just let it air cool, in order to refine the grain from forging,... is really not an accurate definition.

 

The purpose of normalizing is to soften and stress relieve the steel. This is done in order to prepare the steel for stock reduction and or hardening. The grain refinement is really a byproduct of this procedure, as it is with the overall bladesmithing process.

 

The procedure is to heat the steel to just above critical temperature and let it cool, "slowly enough" so that no hardness is attained. 10 series steels can be normalized by air cooling as with water steels in general. Oil hardening steels need to cool a bit slower. I normally leave these inside the forge and let the whole thing cool instead of bringing them out. Air hardening steels will "harden" if taken to just above critical temp and air cooled. To normalize air hardening steels they must cool much slower, like over night. I normally do these in an ash pit type forge. I lay the steel over the coals until it gets up to temp and then bury the whole thing over with hot ashes.

 

What we need to keep in mind is that the "geometry" of a knife blade effects the way it heats and cools. Thin sections will tend to heat faster and cool faster than thicker stockier sections of steel. This makes knife blades unique and is why the "general" metalurgical definitions and procedures often times don't apply.

Edited by Tai

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Tai, your definitions of normalizing are not correct.

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Please define before the flame.

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What's not correct?

 

What's before the flame. ?

 

I have to admit there is a lot of confusion about the purpose and procedure for normalizing knife blades. That's why I made the post.

 

I hear all the time that it's done at the end of the forging process to "fix" the grain. I don't think a properly forged blade needs the grain fixed. It's fixed or should be in the low temp finishing and straightening heats, cycling from just above critical. If thermal cycling is used to specifically and solely to refine the grain, it is not normalizing. It is just thermal cycling. Normalizing is a special type of thermal cycling used to soften and stress relieve the steel, with grain refinement as a secondary byproduct. If the grain is already as small as it can get, then any further cycling is redundant.

Edited by Tai

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If the grain needs to be refined after forging,... something is wrong with the forging. We need to look at the overall process. There are many opportunities for grain refinement in forging, normalizing and hardening, though none specifically designed for it. Although redundant thermal cycling probably won't hurt anything, except maybe fatigue or overwork the steel a bit, it is likely more superstitious than metallurgical.

Edited by Tai

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Tai, no flame intended.I am a metallurgist as are at least two others on this forum....Normalizing reduces stresses, creates a more unifrom and desirable microstructure and refines [by recrystallization] any course structure resulting from forging.....We can stress relieve by heating below critical as often defined in texts as heating between 700-1100F.We can also recrystallize by heating cold worked material just under critical. Normalizing is done by heating to about 100F above critical and air cooling .If is slow cooled [as in ashes ] it is annealing. ...."wrong with the forging "? Well I don't know how many are perfect with their forging but typically one would expect large grains from the temperatures used and a difference in grain size from one area to another. The term 'fix' is not a metallurgical term and " the grain is already as small as it can get "is not something we would expect after forging.[i hope you don't think you can "compact "the metal -there's no such thing !]....My previous post was done while I was not awake enough to give a detailed response.....As a new member welcome to the forum !!

Edited by mete

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I think the whole thing about multiple cycling after forging came as a response to someone suggesting that forging does more harm than good. This may be true for many smiths. However, this is not the way it should be...

 

Mete, there is nothing wrong with looking at it the way you and many others do,... but it is only a matter of "perspective and semantics". I teach and practice killing as many birds as possible with each stone.

 

I hate to say this but,... we're all metallurgists!

Edited by Tai

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A lot of confusion comes when you try to apply general text book definitions to specialization like bladesmithing. We should all be aware that traditionally there has been two sets of definitions, one for metalurgists and one for metalsmiths. The metalsmiths definitions are practical working definitions. I sure am glad that it still says "Bladesmiths" at the top.

 

The definitions I use are the Neo-Tribal Working Blademaster definitions,... straight from the book of Goo! :D

(Those are the only ones I care about.)

Edited by Tai

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Now I'm getting somewhere. :D

 

 

The traditional blacksmith's/bladesmith's definition of normalizing according to the book of Goo is that: "Normalizing and annealing are basically the same thing. The only difference is that normalizing is performed in a blacksmith shop by a blacksmith and annealing is performed in a laboratory by a lab technician"...

Edited by Tai

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... you better write this stuff down. :)

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Here's another good one I just found in the book of Goo:

"Bladesmiths create blades,... and metallurgists create metallurgy." :D

 

So how fine is as fine as the grain will get, in a way we can all understand, observe and relate to? Just curious what your take on it is, anyone?

 

That's the bottom line right?

Edited by Tai

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No matter how many times you thermal cycle it, you ain't never going to see your mirror reflection in it, in the fractured surface,... right?

(Ooops ain't ain't a metallurgical term is it?) :)

 

...Correct me if I'm wrong?

Edited by Tai

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TAI --METE THANKS One from a bladesmith, one from a metal-lab man. I am continuely working my steel at the lowest heats that I can effectively move the metal. I do this to keep from losing as little carbon as I have to . Tell me if I am thinking off base. I feel that after forging and before annealing. I should normalze two or three times and then anneal, so as not use up too many belts. Then I will grind to a 45 micron slightly thick pattern, do my heat-treating sequence then tempering sequence. Then a final grind and polishing sanding. With a final fine grit sanding. I don't have any clay so I heat treat with a torch. Temper in a Paragon Furnace. The edges are file skitting hard and the spine is easily cut with a file.The steel I have been using is 1095--5160 and some ball-bearings I believe to be 52100. I went to the torch on the 5160, 52100, because I kept coming up with too brittle blades. Does it sound like I could use some help??GRIN

 

Chuck Bennett

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I think that sounds right,... depending what you mean by normalize and anneal? What some people call normalize others call anneal.

 

Just don't do it backwards where you anneal first then normalize.

 

Does it take three times to finally get it normalized or are you actually normalizing it three individual times?

 

Why not skip normalizing and just anneal it three times? :)

(... better make it 12 just in case.)

Edited by Tai

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This must be one of those "other enigmas".

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TAI I have in my mind that the reason for the repeated noramalizing is to drawing the grain down to as fine as you can get it, less chance to have a blade chip and be easyier to sharpen a field knife.. I anneal so that it does not wear my belts out so fast. If I am not thinking right, I would like to know. I have been stock removing for several years but started forgeing about a year ago. I am trying to learn the correct methods to make a really tough, easyier to resharpen that will not break if you have to abuse it. Chopping trees or hanging from it in a crack in cliff.GRIN. Some of the folks that by my knives really use them hard. Professional guides and hunters, cowboys. To answer your question on normalizing-- I normalize three separate times, go thru three heat-treats and at least two tempering, some times three if it is still too hard.

 

Chuck

Edited by CBENNETT

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you know i could have sworn normalizing and anealing were the same damn thing.

write out what you do for both as far as i know you heat to crit and air cool slow to give the metal a softer texture this allows for you to grind easier and reduces chipping during the whole process, if I'm wrong i guess i need to reread everything I have studied over the last year and a half. 8|

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DRACOZNY(SP) What I do for normalizing is--Heat to critical and set inside turned off, heated furnace for as slow a still air cool as I can get, about six or seven hours. Annealing is when I take above critical maybe 50 or so degrees and then stick in a bucket of HOT ashes. Takes about twenty to twenty five hours to cool.

 

Chuck

Edited by CBENNETT

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I learned that annealing was the way you described normalizing but for air hardening steels you needed to cover it to cool slower.

shrug* to each his/her own I think

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I normalize while I'm forging, annealing and hardening, but when I'm normalizing I'm actually annealing. :)

 

Seriously Chuck, it doesn't sound like anything is wrong with your process that should cause brittle blades. About all you can do is try tweaking some of the temps "and times" a little. I would have to "see" your whole process. You can always try a different steel. According to some definitions I'm combining normalizing and annealing, but I don't like to look at it that way. It gets confusing.

 

The word normalize comes from the root word norm which means: The model, the average or the standard.

 

To normalize means to make uniform and normal.

 

If the metallurgical definitions that Mete gives for normalizing and annealing are correct then nothing actually gets "normalized". If normalizing simply means to heat to just above critical and air cool, then it anneals water hardening steels, leaves hard spots and or partial hardness on blades from oil hardening steel and it hardens air hardening steels. Nothing gets "normalized".

 

If there are hard spots or partial hardening, it is "NOT" normalized.

 

"To normalize oil hardening steels they need to cool a bit slower."

 

If it's an oil hardening steel you are using then the triple normalize is really a triple thermal cycle with hard spots or partial hardening and your annealing is really normalizing.

 

You go through the whole process with "as many cycles as it takes" to finally get the steel "normalized", one time.

 

To repeat the normalization is redundant.

 

Normalizing and annealing are basically the same thing. Annealing is the theoretic ideal. Normalizing is the practical application of that ideal. I avoid using the term anneal in regards to bladesmithing, because it represents an absolute, which only exists in the text book and in the mind.

Edited by Tai

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