How to normalize 1095?

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So it is up to Non magnetic and cool to black then heat treat?
 
Thanks for all the info, guys. Lots to absorb. My knives are "fine" now but not too many of us do this to make "fine" knives! Sean, I'll be in touch about the salts eventually. Hopefully soon. Until then I'll caveman it a bit and see what I can produce. I don't even know if the "grain" I mentioned in my knives is REALLY grain. I tried to take some macro pics but I just can't see it. It's almost a feathery sort of look, so I assume that's grain. Anyway, hopefully this weekend I can go nuts on grinding and I'll try this fancy shmancy normalizing thing and see if it's any different. And, if it's worse I'm going to pump iron for the next few months and then go out to Nick Wheeler's place and kick some as$! :D LOL!
 
Heat to a temp at or above Acm to equalize grain size (don't worry about that size on this one, just as long as it is uniform), and pull all carbon into solution and evenly distribute it. Next heat in increasingly lower cycles to refine the grain and the carbides. By finishing up at subcritical you also give it a good stress relieving/annealing effect.

There is a huge difference between normalizing and annealing, although those who do not understand the underlying processes often confuse them by simply looking at the techniques. Normalizing is for evening things out, regardless of resulting hardness, annealing is for the specific purpose of softening (via recovery, recrystalization and resulting microstructure).

The reason one must lower the subsequent heats if many cycles are done is to beat the grain coarsening temp which lowers with grain size. There is a point of diminishing returns however.

I could give an exacting explaination as to how and why all this works but with the "Blade" show looming...

I could also cite many texts, references and spec sheets, but well...
So could anybody else if they hit the library ;) .
 
Here's a little tip that I was told about and used several years before I purchased my heat treat oven. When you don't have a salt pot or heat treat oven and you have to rely on your forge for all your thermal cycling and heat treating (hardening). First get a good magnet and attach it to a handle about 2 ft. long,
second get a piece of heavy walled pipe a little longer then the length of your forge chamber ( it doesn't need to be stainless) 3"-4" in diameter. I always used the 4" but that will depend on your forge chamber size. My forge is also a veritcal forge so this gives a more even heat around the pipe then a horizantal, because the heat surrounds the pipe and doesn't lay with one side against the floor like in a horizantial but with either forge this techniques works very well. Now fire your forge up, (plug the far end of the pipe up with a piece of kaowool or you can weld a cap on, but I always just used kaowool, this way I could remove it and pass completely though the pipe out the back of the forge with really long blades.) Now slide the pipe into your forge and let it turn orange. After the pipe has turned good and orange, place the blade in the pipe backwards, leaving the cutting edge and tip of the blade out side of the pipe. When the tang and ricasso area start to show a good red color but not yet nonmagnetic, remove the blade, now quickly holding the tang end with your tongs and holding the blade fairly centered in the pipe so it doesn't touch anywhere. move it in and out of the pipe, this will keep the blade protected from direct flame and let the steel heat more evenly without hot spots,after a few seconds and the blade is starting to show some red in the cutting areas turn the flame off and just work with the radiating heat from the inside of the forge, continue to move the blade in and out of the pipe until you get a good even nonmagnetic. As soon as that occurs, let the blade cool to black steel and reheat 2 more times. When you don't have the more expensive equipment with heat control, a magnet is your best friend, just take your time and don't hurry, these cycles are what will determine the quality of your finished knife,so patience and practice is the key. Have fun and I hope this helps someone.

Bill
 
NickWheeler said:
I first got the idea for the multiple thermal cycles from reading archived posts from SwordForums by Howard Clark, Don Fogg, Randal Graham, and Darryl Meir. Add some more names like Jimmy Fikes, and you are looking at the men that know heat-treating blades inside and out.

I am not into hocus pocus, chicken blood, or witches brew. I started with numbers in books, and the word of men like I mentioned above.

I have tested to destruction something like 130 blades.

That is why I think what I do works.

I have tried just a couple thermal cycles at the higher temps, and the blades did not hold an edge very well, deformed rather easily, and broke easily. When I looked at the crystalline structure, it was coarse like raw sugar.

When I break blades done the way I described above, they look like they don't even have grain. It's a very very fine grey... These blades hold an edge well, are much tougher, and much more difficult to break.

I'm not saying I'm right-

What I'm saying is if you make a blade the way I described, it will work well.

As Sean mentioned, coil heat treating is very cool, but not very realistic for most knifemakers.

Chiro, to get back to answering your question.

Without the equipment I have, I would take the blade up to the point that it loses the all shadows. This can really only be seen in a completely dark shop... so doing it at night really helps.

I would recommend you do that at least 3 times, letting it cool to black between each heat. I think you would be impressed with your results if you took a few more minutes and did it 2 or 3 additional heats.

Of course you don't HAVE to, it's just a suggestion ;)

:D -Nick- :D
Click to expand...

seems like good info, gonna try it
 
First, that chart is for tool and spring making ( probably) and the temps are quite off for blade making.

OK, lets look at this from inside the steel and maybe we can get a better idea of how to design a heat treatment regime. I am going to round off the numbers to even tens.

If we forged the blade it has been through dozens of cycles of heating to well above the solution point of the steel, and then air cooled to below the critical point. The grain has probably grown significantly. The alloys are probably in good solution, with the temps being so high in forging - 1600-2100F - but we need to do something about the grain structure before hardening.
If we ground the blade, it is the same structure as it was when we got it....which was???????? So we should get it to a condition we know about.

These conditions are taken care of by normalizing....which means ,"returning the steel to its normal condition."

When steel heats up enough, the structure converts to austenite. This starts to happen above the critical temperature or around 1350F. It becomes fully in solution at approx 200F above that point. This is the needed temperature for normalizing. In normalizing, we want all the steel to be austenite....at or just slightly above the temperature for full solution. Most charts will list 1095 as full solution at 1570F.....so that is where we want to stop and hold at for a knife blade.
We hold it at that temperature to allow things that dissolve slower than ferrite to get into the mix.
Now the steel is in solution, the grain structure has re-assembled itself, we have kept it there long enough to allow things to get set up , and all carbides and other alloy ingredients are distributed. Then we cool the steel fast enough to get the job done, but slow enough to assure that the steel converts into pearlite, not martensite. Plain air is the media for this task. Now the steel has a fine grain, and things should be in good shape internally. For a knife blade, we often cycle this again two or three more times. Since the alloys are all distributed, and the grain is re-set, we don't need to raise the temperature as much above the critical point as before. We give it a second cycle at 100 above critical....or 1450F, and a third right at critical....at 1350F. This reducing series of cycles refines the grain to its best state for a knife blade. A final cycle at about 50F below the critical point is just a spheroidal annealing, and while some add it, there is no gain to the blade if the next step will be the quench. Spheroidal annealing is very beneficial before grinding, and at the end of a days forging.

So, the chart for 1095 KNIFE BLADES is :
Normalize - 1550-1570F, hold for 5 minutes, to assure full solution, air cool to below 900F. Repeat at 1450F and 1350F.
Full Annealing- Heat to 1475F and hold for 10 minutes. Cool at 50 degrees per hour to 1200F, then air cool to room temperature.
Spheroidal Annealing - Heat to 1250-1300F and hold for 10 minutes, cool to below 900F. Cooling rate is not important.
Hardening- Heat to 1450-1470F and hold for 5-10 minutes ( the longer time for thicker objects). Quench in a fast quenchant - water, brine, Parks #50, or similar fast oil.
Tempering - Heat to 400-475F and hold for 2 hours. Cool to room temp by water quench and repeat for a second cycle. Final hardness range from Rc61 to Rc57 with these temps on water quenched 1095.
 
PG spheroidized annealed 01 has very fine grain when you get it. It needs no thermocycling before HT, unless forged. From what I have read above, all of you need to go back and read Kevin Cashens stickies on hypereutectics, or talk with Mete'. BTW, forged steel blades are no better than those by stock removal, all things being equal. Forging does absolutely nothing to improve steel, but the proper HT does.

I see that Bladesmith has answered your questions very well as I typed.
 
I think a lot of the confusion over normalizing comes for several reasons…

The word normalize or normalized etc., has two different meanings. One, it’s a term used for a “process”. Two, it’s a term used for a “state”. The process is supposed to result in the state if done correctly. The process is only correct if it results in the desired state.

Also, if it takes multiple thermal cycles to achieve the desired state,… then it’s not truly “normalized” until after the last cycle.
 
In case you hadn't noticed....

This thread is 3 years old and the member you are trying to communicate with has long been banned from the forum.

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