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The Newbies Arena Are you new to knife making? Here is all the help you will need.

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  #1  
Old 08-31-2011, 08:54 PM
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jcoon8283 jcoon8283 is offline
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Newbie needs some help!!!

First of all let me thank you guys for taking the time to check this post out. I have been around here for a while checking things out and trying to get a handle on this knife making thing lol. So I have some questions about heat treating, and more specifically heat treating 1095. Now from what I understand lurking around here 1095 is not easy to treat, but I did get a bucket of parks #50, and I have a kiln, so hopefully that will make my chances of success even greater. Upon looking through multiple posts here I have found a lot of general info on 1095 and was in some need of some more specific info on temps and such...so here goes.

#1 What temp must I absolutely reach in the kiln for the right heat treatment to occur, I have heard 1450-1500 but that seems like a broad range to me... any specific temps I must reach?
#2 What temp does carbon loss begin at and what temp must I not exceed with 1095 in heat treatment?
#3 How long of a soak do I need for 1095
#4 When quenching how far does the knife need to be submerged in the oil (just submerged, six inches deep in the oil etc), and does it matter whether the knife is oriented vertically or horizontally, edge up or down?
#5 When doing the file test what am I looking for, that the file will not even leave a scratch whatsoever, or is it that it just doesn't bite and cut like it normally should?
#6 When tempering what temps do I need to reach rc 58-60, I have read around that the neighborhood is 450-500 degrees but again that seems like a broad range....any specific temps?
#7This one is about the metal itself before heat treating. To what level do you guys finish your knives before ht. I have left the edges on all my knives so far waiting to be ht about the thickness of a dime. But, do you guys ht after like a 60 grit finish, 220, 400, etc?

Again, thanks for all the help in advance!! I know there's a lot of questions here, but I cannot find the answers to these questions anywhere on the net and I think I'm gonna tweek if I click another broken or dead link. Thanks!!!
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Old 08-31-2011, 09:56 PM
Doug Lester Doug Lester is offline
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1-3. 1450-1500 is not all that broad. I'd split the difference and try for 1475. That should keep you between the lower and upper critical ranges. I would soak for at least 5 minutes but being that you have a regulated oven that you can keep a lower temperature in, as compared to a forge, 10 minutes would be sure to get the maximum carbon into solution in the austinite without causing undue grain growth. Don't worry about carbon loss; you won't see it at the temperatures you'll be dealing with. That doesn't happen much until you get up to around and above welding temperatures and can be mitigated by keeping a fuel rich atmosphere in a forge.

4. The part of the blade that you want to harden needs to be submerged in the oil. That means that unless you want to have to get carbide bits to drill the tang not to submerge it until it has lost color. If you want to do an edge quench you will want to quench to about half the width of the blade and an equal distance back form the tip. You can quich horizontally or vertically though I would hazard a guess that most makers quench verticallly unless they are edge quenching. The emportant part is to put the blade into the quenchant straight. You should put the blade in edge first if you are quinching horizontally and point first if vertically. Some people agitate the blade up and down slightly others cut it through the guenchant. Do not move the blade side to side unless you really want to have fun straightening out the blade. Personally, I insert it into the quenchant and leave it there until the tang looses color and the blade has had enough time to come down to about the temperature of the quenchant, which I think for Parks 50 is about 90 degrees. Check any intructions that came with it.

5. When doing the file test, the file may bite a bit into the scale that developed on the blade during austinization but no more.

6. I would start tempering at more like 425 degrees. I would recommend three two hour cycles to convert as much retained austinite as possible. After you put a rough edge on the blade you can try to cut some soft iron wire or a thin rod of bass with it by stiking the blade on the spine to try to drive it trough. The edge should neither chip or indent. If it does chip a little all you will need to do is grind out the chip and retemper at about 25 degrees higher for a cycle and test again. If it looks more like the steel indented and folded over you will have to re-austinize the blade and re-temper at about 25 degrees lower.

7. I like to finish knife out to 220 grit. Others might stop at 120 grit but Parks 50 is a little agresive. It's probably a good idea to leave the edge of the blade about the thickness of a dime or just slightly thinner to help avoid warping. Although I have had to quench blades with a rough edge that I had to re-harden without trouble but why make life harder when you don't have to.

One thing on quenching the blade. You must have the steel at austinizing temperature when it enters the quenchant. You will have less than one second to drop the temperature of the steel to below 1000 degrees or you will start to form pearlite. What all that means is that your heat treating oven must be very close to your quench tank. Ideally you should be able to pull the blade out, turn slightly and put the blade into the quenchant tank.

Doug


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Old 08-31-2011, 10:01 PM
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Ray Rogers Ray Rogers is offline
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I use 1475 for 1095, holding that temp for 10 minutes.

Get the blade from the heat into the oil as fast as possible, say 3 seconds max. Oil should be at 125 - 150 F

Don't worry about carbon loss, a non-issue

I quench point first but the other ways work just as well as long as you actually get the blade into the oil fast enough. Any depth is OK as long as the blade is covered and as long as there is enough volume of oil to take the heat away from the blade (I like 3 gallons).

A fresh file should skate off the steel or cut slightly.

Tempering temps vary a little with the oven, mine gets Rc 58 - 59 at 435 F for 1 hour (done twice). Begin the temper as soon as possible after the quench because 1095 will crack if left sitting at room temp for too long a time. Never temper beyond 500 F with this steel.

I grind my bevels entirely after the HT is finished. This avoids many warping issues and removes pitting, decarb, and any other surface problems....


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Old 08-31-2011, 10:51 PM
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jcoon8283 jcoon8283 is offline
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Originally Posted by Doug Lester View Post
That should keep you between the lower and upper critical ranges.
Doug
Thank you so much guys, that was just the info I was looking for. Oh, what are the upper and lower critical ranges speaking of temps? Hopefully saturday I will be giving this a shot for the first time so wish me luck, and say a prayer for me. By the way I guess I should ask from you guys that have done this before. What chance do I stand starting a fire by dunking a 1500 degree piece of metal into a vat of oil?
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Old 09-01-2011, 12:37 AM
Doug Lester Doug Lester is offline
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The lower critical temperature is the A1 point that's where the steel starts to convert to austinite and the upper critical temperature for 1095 is the Acm point where the austinite becomes stable. With hypereutectic steel such as 1095; hypereutectic means that the austinite is supersaturated with carbon, over 77 points; grain growth starts to excellerater over the Acm point though this can also be effected by whether the steel was deoxidized, killed, with aluminum or silicon.

With hypoeutic steel such as 1060, non-saturated with carbon in the austinetic phase, the upper critical point is refered to as A3. A hypoeutic has less than 77 points of carbon.

The A1 point is not effected by carbon content but it is effected by other alloying elements. The A3 point decreases with an increase in carbon content until the the euticoid point is reached att 77 points and the austinite is saturated with carbon without any carbon being left over. After the euticoid point the Acm point increases with the carbon content. If you want this sketched out google carbon phase diagram but you might just want to take my work for it for now.

That was just for general information only at this time. Starting out I would recommend that you basically cookbook the heat treating the procedures for the steel that you choose. Even basic steel metallurgy can make your head spin and you have enough on your plate getting the basics down. If and when you feel that you need more information on metallurgy as it referes to knifemaking there are some good books out there.

Doug


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Old 09-01-2011, 01:26 AM
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jcoon8283 jcoon8283 is offline
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Quote:
Originally Posted by Doug Lester View Post
The lower critical temperature is the A1 point that's where the steel starts to convert to austinite and the upper critical temperature for 1095 is the Acm point where the austinite becomes stable. With hypereutectic steel such as 1095; hypereutectic means that the austinite is supersaturated with carbon, over 77 points; grain growth starts to excellerater over the Acm point though this can also be effected by whether the steel was deoxidized, killed, with aluminum or silicon.

With hypoeutic steel such as 1060, non-saturated with carbon in the austinetic phase, the upper critical point is refered to as A3. A hypoeutic has less than 77 points of carbon.

The A1 point is not effected by carbon content but it is effected by other alloying elements. The A3 point decreases with an increase in carbon content until the the euticoid point is reached att 77 points and the austinite is saturated with carbon without any carbon being left over. After the euticoid point the Acm point increases with the carbon content. If you want this sketched out google carbon phase diagram but you might just want to take my work for it for now.

That was just for general information only at this time. Starting out I would recommend that you basically cookbook the heat treating the procedures for the steel that you choose. Even basic steel metallurgy can make your head spin and you have enough on your plate getting the basics down. If and when you feel that you need more information on metallurgy as it referes to knifemaking there are some good books out there.

Doug
Wow, reading that about made my head spin. Well the reason why I wondered about the upper and lower critical ranges was not that I wanted to experiment with heat treating, but that I wanted to stay away from negatively affect the metal I have in any way. At this point I really don't have a whole lot of blanks to experiment with, nor can afford to. That's why I want to get all the specifics that I can about this process before I start. I hate wasting anything so I am definitely going to "cookbook" it as much as I possibly can. BTW at what point does undue grain growth begin...length of soak, or too high a temp in the ht, or a combo of both? Thanks for all your help!!!

Last edited by jcoon8283; 09-01-2011 at 02:02 AM.
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Old 09-01-2011, 10:59 AM
Doug Lester Doug Lester is offline
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Grain growth is more a factor of temperature than time though time does have an effect. That's why we say to soak at 1450-1500 degrees instead of 1800 degrees but, by the same token, you don't want to soak at 1450-1500 degrees for an hour. Five to ten minutes will get adequate carbon into solution in the austinite without have to worry about grain growth. Hypoeutectic steels that can be austinized at about 1600 degrees to get the carbon into solution are only soaked for about a minute.

The alloy also a funtion. Elements like chromium, tungsten, and vanadium inhibit grain growth. Deoxidizing with aluminum also puts a drag on grain growth. Deoxidizing with silicon does not inhibit grain growth. These are some of the factors that influence the formation of course grain but it's hard to say that below point X grain growth is minimal and above point X it really takes off. That's why we generally go for the lowest temperature that will disolve carbon at the shortest period of time for a particular alloy of steel.

Doug


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Old 09-01-2011, 11:12 AM
Doug Lester Doug Lester is offline
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Grain growth is more a factor of temperature than time though time does have an effect. That's why we say to soak at 1450-1500 degrees instead of 1800 degrees but, by the same token, you don't want to soak at 1450-1500 degrees for an hour. Five to ten minutes will get adequate carbon into solution in the austinite without have to worry about grain growth. Hypoeutectic steels that can be austinized at about 1600 degrees to get the carbon into solution are only soaked for about a minute.

The alloy also a funtion. Elements like chromium, tungsten, and vanadium inhibit grain growth. Deoxidizing with aluminum also puts a drag on grain growth. Deoxidizing with silicon does not inhibit grain growth. These are some of the factors that influence the formation of course grain but it's hard to say that below point X grain growth is minimal and above point X it really takes off. That's why we generally go for the lowest temperature that will disolve carbon at the shortest period of time for a particular alloy of steel.

Knowing the technical terms can help you follow discussions on these boards better but it takes time to pick them up. Some of the books like Wayne Goddard's The $50 Knife Shop or Jim Hrisoulas's The Complete Bladesmith can help you out on some of these. There may even be a list of terms somewhere on this board. You can at least do a search for the terms on these boards to help get a handle on them.

Doug


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