steel hardening question


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OH_Spartan
November 21, 2011, 08:14 PM
Hey gents,

Thanks to the education and prodding of many of you, I have tackled my first knife. I chose 1080 for my first project because it was easy to heat treat and temper.

I also asked a favor of a friend that works at a machine shop and he agreed to cut my blank for free if I programmed my profile in ACAD.

Well....when I got my blank back, he had messed up my 1080 and cut a second blank out of A2 tool steel. The catalog said it should be heated to 1725-1775 then air quenched with cold air.

Will this type of steel still form a hard, tough knife if I quench in peanut oil (like I would have done with 1080)?

If not, can I air quench with my air compressor?

How will I know if I get to 1725-1775? If I understand correctly, 10xx series steels can be treated to non-magnetic (1425-1500) then quenched in oil. I don't have a fancy forge.

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hso
November 21, 2011, 09:16 PM
http://www.bladeforums.com/forums/showthread.php/570302-Air-Quenching

JTW Jr.
November 22, 2011, 02:01 AM
Do you have a way to hold it at 1775 degrees for the time needed ( 40 mins ) ?

hso
November 22, 2011, 10:25 AM
Some folks have suggested using kiln cones (http://www.bigceramicstore.com/information/ConeChart.html) to tell when you reach max temp, but they don't help much to tell you that you are at/below 1775.

You can spend a lot of money on an optical pyrometer or you can save a bit and use a direct thermocouple.

All this is assuming you can actually control your forge to get that temp and sustain it.

JVoutilainen
November 22, 2011, 12:15 PM
Well, the datasheet for the A2 does not look very promising considering that it is your first, and because you do not have the necessary equipment.

I have dabbled with knives on and off for five or six years now, and the most complicated thing I am willing to try my hand at is Wr 1.2210, which is a high carbon steel with 0.7 Cr and 0.1V... and that is hard enough to forge, and heat treat properly.

Maybe it would be a good idea to hold on to that piece of A2, for now, and try something a bit more straight forward first.

JohnKSa
November 24, 2011, 02:02 AM
You can probably find someone to do the hardening for you if you poke around. I know a guy who makes/sell knives but doesn't do any of his own hardening/heat treating.

OH_Spartan
November 26, 2011, 08:22 PM
A wiser man would have taken JV's advice. For better or worse, I'm known better for my enthusiasm. That, and, I'm almost out of vacation and this is a Christmas present for my dad.

I'll post final results when I get the knife done, but I think I was able to get and keep the temperature using a charcoal/hardwood fire and a couple hours of rapid fanning.

I'm done with A2 until I get a real forge.

hso
November 27, 2011, 01:17 AM
I think I was able to get and keep the temperature using a charcoal/hardwood fire and a couple hours of rapid fanning.

Not likely, but good luck to you regardless.

JVoutilainen
November 27, 2011, 02:35 AM
For better or worse, I'm known better for my enthusiasm.

:D Who could honestly call that a bad thing.

Besides, because it is your first there is actually a chance of success... of sorts. If it was your second I would be more skeptical. If it was your third, there would be no hope, whatsoever.

Once you start understanding the pitfalls you'll invite Murphy.

Good luck!

OH_Spartan
November 27, 2011, 12:28 PM
Here's the way I look at it

If I didn't get it hot enough, it will be as soft as it was when it was annealed.
If I got it too hot, it would have cracked upon quenching. This is VERY low risk given my process.

The blade was completely red and started turning orange around the edges and point. I covered it with coals and burned a bunch of dry oak fire wood, fanning constantly. The fire was incredibly hot and burned through a lot of wood over about an hour. The blade was orange when I pulled it out.

When shaping the knife, my file cut the steel very easily. Now, it barely grazes it. The steel is significantly harder than it was.

This process is inadequate for anything except "I hope it worked." I would not recommend it to anyone, especially for their first project. I won't be using this process again. However, I think I stand a "reasonable" chance of success. No one can prove me wrong and I can't prove myself right, we can just speculate on the definition of "reasonable."

Worst case, I'll show up at Christmas with a knife only a father can love.
EDIT: When I was in the garage cleaning and polishing the blade, I tried to drill a hole in the tang...I could not do it. I was afraid I would break my bit and barely even left a divot. This was the same bit I used prior to heat treating and was able to drill the tang.

hso
November 27, 2011, 09:15 PM
Recommend to draw the hardness out of the tang and spine.

JVoutilainen
November 28, 2011, 04:18 AM
Considering the material, annealing parts of the blade at this stage, with very limited equipment, might turn out to be problematic. This is one reason I stick to relatively simple carbon steels.

Have you tempered the blade yet? I would suggest you do a meticulous tempering according to the manufacturers specifications. I have noticed that with alloyed steels extended tempering periods often increase flexibility and toughness of the steel, without compromising hardness (much). I do it by proceeding to temper as instructed by the datasheet, but, continue the process by lowering the temperature some and extending the time to many hours. Unfortunately I have no idea whether this would work with the A2. Whatever you do, you should follow the manufacturers instructions on how to temper the steel after hardening to lower the possibility of the blade being brittle.

Edit: and you should always temper the blade immediately after hardening, because hardened steel is in a state of stress, and might easily crack.

OH_Spartan
November 28, 2011, 08:03 PM
I did temper the blade. As soon as it cooled to touch, I put it in a toaster oven set at 500 F for two hours. (I put an oven thermometer in there and it read about 475). I did an additional temper of the spine and tang, per HSO's advice. With the ground edge in suspended in water, I heated the blade with a propane torch until the back side of the blade just barely turned blue.

The manufacturer says to temper between 300-1000 F, with 300 F = 62 Rc. The hardness levels out at 56 between 500 F and 1000 F. This site doesn't come from the manufacturer, but it give a ton of great technical info.
http://www.bucorp.com/files/aisi_a2.pdf

This first project has turned out to be way more than I bargained for. That said, I have learned way more than I expected to :D. After this, 1080 or 1095 will seem boring.

I do appreciate the discussion, and advice I've gotten. Without it, my dad would have gotten a flannel shirt for Christmas.

HellBlazer
November 28, 2011, 11:44 PM
If I was you I'd email Bark River Knives & ask them. Almost every model they make is A2 & they make some great knives.

jacquie@barkriverknives.com

thesurvivalbeast
February 17, 2012, 05:53 PM
Hello,

This is the very first time I have been in here. But I wanted to say that I have both high carbon and stainless steel knives and I will say this: My handmade 1095 high carbon survival bowie knife is awesome and gets super sharp. my Outback Bowie knife which is made with 440C stainless steel is very hard to sharpen and to me does not hold the edge for very long at all. Now, I have the Hibben Extreme Survival Survivor knife and it is made with AUS 6 steel. And I will tell you right now, that knife gets a keen razor sharp edge and it hangs onto it too! This knife has much better edge retention and gets much sharper than my Outback Bowie knife. Now, I also have a handmade bowie knife that is made with 01 tool steel, and the heat treatment on that knife must be estremely poor because no matter what I try and what I use, that damned knife just will not get sharp at all! I posted my thoughts of my new Hibben Survivor knife on a forum along with pics of it and the handmade sheath I just had made for it, and some guy on there who undoubtedly just has no idea what he is talking about, came on there and said that AUS 6 steel was a very very poor steel for knife blades and any knife made with it is just wall-hangers and not made to use at all. he even embarassed himself further by saying that AUS 5 steel has no heat treatment whatsoever and therefore is what makes it suck so bad (well, that was his meaning, but he didn't use thos exact words). I just had to laugh when I read his non-heat treatment statement. I know of No steel, stainless or otherwise, that does not have some type of heat treatment to it. In closing I want to say that it is not the typer of steel that makes an awesome knife blade, but moreso it is the way that it is heat treated that makes it an outstanding knife blade. And I will tell you, the heat treatment that my awesome Hibben Survivor knife has must be just right, because it is one big badass knife that will hold its sharpened edge like no tomorrow! I would trust the knife with my Life! Thanks for reading!

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