How To Heat Treat 1095

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BOOGERH30

Joined
Jul 17, 2005
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Hi i made my first knife and would like to know how i can go about heat treating it. It's made from 1095, and any help would be Greatfull.
 
Howdy, and welcome to knifemaking! :)
I am fairly new to knifemaking, having made 2 total, but have worked on several others, with friends and family who have all wanted to make a knife. The only steel I have used is 1095, and here's my experience with it:
it takes several times of heating up 1095 to get optimal hardness. I have had the best results when I heat it up slowly, say, over the course of 20-25 minutes, to non-magnetic temp. I do this, then let it air-cool down to where it can be touched with the hand. Then, I heat it up again, this time over about 15 minutes, to non-magnetic. Again, I will let the knife air cool. I will always heat it a third time, too. If the knife is smaller (1/8" thick steel, less than 4" long blade), then I quench after the third heat cycle. If the knife is larger, being it's thicker than 1/8" or longer than 4", then I'll do more heat cycles.

When quenching 1095, it's imperative tht the quench happen very quickly after taking the knife out of the heat. I check for non-magnetic and, if it's there, I throw the knife back in the heat for about 25 more seconds. Then, I'll take it out and immeditaely quench it in the oil pan, which is placed as closely as possible. Now, let's talk about the quench: per Admiral Steel's website instructions, I have played with water quenches and water-oil combo qhench. And, I've always cracked or broken blades when quenching them in water. From my experience, using water on 1095 is just too rapid of a cool. Instead, I use a vat of hydraulic oil (it's a bit less thick/viscous) that I picked up from Wlamart for a few bucks. I heat it up with an old file that's been soaked in the heat with the knife. Then, I quench the knife.

So, that's how I heat treat 1095 and I've been happy with my results, thus far. I got the multi-heat cycle method from both trial-and-error and reading posts here and at knifeforums.com on how to treat 1095. The key to heating it properly, IMO, is to cycle it slowly, numerous times, before quenching. I've had the best results with this method.

By the way, I don't have a heat-treating oven, so I use an old BBQ grill and a shop-vac that's set to the blower function. I keep the shop-vac regulated, though, via a small pipe system with holes drilled into it, in order to keep the heat evenly dispersed and to keep the knife from heating up too quickly. A hair dryer will wrok, too. It'll take a bit longer but, in the case of 1095, that's actually a good thing.

Good luck and let us know (and see pics of! :) ) your results. Keep on posting with any other questions you have!

-Trout Tamer
 
Good advise from Trout tamer.ATF works as a good beginer quench for 1095.
The thermal cycling creates fine pearlite,which is the best structure to convert to austentite at the critical temperature.The soak temperature you want is about 50 degrees above non-magnetic.The hardening temperature for most simple knife steels is 25 to 50 degrees above critical.It has to be held at this temperature - and not higher_ for a long enough time to allow full austenization.If you do not hold the steel long enough (for a small blade about 1-2 minutes) only the surface will be austentized,and the blade will only be case hardened.Carbon steel with .83% carbon is the eutectoid.It has the lowest critical temperature for hardening,normalizing,spheroidizing,and annealing.That is why 1080 and 1095 are good started steels.(the magnet trick works closest on them)
The step he didn't add is to temper it at 425 for 1 hour immediately after quench.Cool to room temperature and temper again.This converts the retained austentite to martensite (1095 has 15 to 20% retained austentite at room temperature).Left untempered,or delayed too long and it becomes unstable.
Stacy
 
My opinion is that 1095, generally speaking, is not a good steel to begin with except in the sense that it can teach you quickness in handling. It is a most unforgiving steel between oven and quench. My best is about 1 second from furnace (oven) to quench. For optimum results 1095 requires less time exposure than that before quenchant.

RL
 
Roger,I understand where you are coming from.But ,from a teaching standpoint ,1095 has the lowest hardening temperature of any simple carbon steel.O-1 has alloying elements to retard the conversion time to martensite,which is why many makers find it easier to HT.As far as beginners learning to HT,1095 (if properly heated and soaked) will not loose enough heat in the transfer to quench to miss the conversion nose.There is a range of about 40 degrees between the austentitic formation and full solution(between Acm and Ac3).If you austentize at 25 to 50 above Acm,and soak until it is in full solution,the metal has plenty of time to drop in temperature before transformation begins at Ae1 (around 1350). Any good oil quench, of sufficient volume,will lower the temp to below martensitic temp (Ms) in the time required.It is a fairly fast quench time,but it is still the least drop in temperature required for any simple carbon steel.As to learning to anneal,spheriodize,and normalize steel,only 1080 is closer to the eutectoid than 1095. If you master the working and treating of 1095,and have learned what is happening within the steel,you will be able to handle any alloy steel much better.Many new makers either water quench 1095 -BAD IDEA,or don't use enough quenchant to absorb the heat from the blade.Those two things ,and improper heat control, are the main cause of failure with 1095.
I realize that many people use other steels,but there is a reason that industrially(not counting stainless)most cutting implements are made from 1095 (Up until a few years ago most of the worlds production of 1095 went into shears,cutting tools,and razor blades).
All this aside,if new makers would study a little basic metallurgy before putting the blade in the fire,they would have a better success rate with whatever steel they learn on.I worked with Dr.Davidson,a famous research chemist, who used to say," You learn from your mistakes.But all you learn is what won't work.What you learn from success is what will." Or in the words of Bill Moran,"When I figured out how to make damascus,I tried 1000 ways to do it.I found 999 that won't work."
 
The step he didn't add is to temper it at 425 for 1 hour immediately after quench.Cool to room temperature and temper again.This converts the retained austentite to martensite (1095 has 15 to 20% retained austentite at room temperature).Left untempered,or delayed too long and it becomes unstable.
Click to expand...
oops, I forgot to add that, good catch! Yeah, that's right around where I usually temper at; I'll go down to around 410 for smaller blades, though, if I'm wanting a harder overall finish (that being, if I'm not expecting to be prying, batoning, etc with the knife). But, I'm always learnin'!
 
On tempering, 400F. always got me around 58.5 HRC and a real fine blade out of 1095 when I was hardening in a forge and #50 oil. With a reasonable soak time and extra pro-eutectoid cementite pulled into the mix that more involved equipment may provide, it stands to reason that higher tempering tempertures may be necessarry. One needs to remember that the second more diffusional phase of tempering doesn't really get moving until you go over 350F. so one shouldn't see any effects on hardness until around 375F. and then you may drop from 65HRC (as-quenched) to perhaps 64 or 63HRC, still way too brittle for service. I often hear fairly well known smiths that speak of tempering at temperatures below 375F. and not encountering brittleness. Furhter investigation almost always reveils that they are either working with a medium carbon steel, heating with forge or torch, or quenching into a material that has less then the minimum thermal exaction rate for the steel, which all makes the bottom line that the steel never reached a hardness where brittleness would be an issue. Which makes an excellent transition into my second point...

Speed of quench; mete and I just had this conversation on another forum, regarding how the race to get 1095 cooled does not start when you pull it from the heat, it starts at Arcm (depending upon you austenitizing temp) and gets more and more critical until you reach Ar1 where it becomes a mad dash to avoid pearlite.

Now in English- unless you have the blade really losing color as you walk from one side of the shop to the other, the speed of your hand has little to do with the steel avoiding the TTT nose, this is the "gentleman start you engines" part so if you take too long to start your engine you will be out of the race but the race has not started yet.

As soon as it starts cooling and things are out of your hands and becomes the quenchant job, that is when the flag is dropped and things have to move. It is in the zone that pearlite likes to form where things are the most critical (from approximately 1250F to 900F, to be safe). Making it to 850F. without any diffusion is like making it to the checkered flag witout skidding in ot the wall at any point. Many folks (sometimes I fear, most) will scrub the wall quite a bit and not even know it since they still manage to limp across the finish line.

So you see it is not your hands, or feet, that have to be really fast, it is your quenchant, perhaps this will give some insight as to why I am so darned anal about quenchants.

1095 has got a bad rap in the past and seems tot be the target of a lot of prejudice these days, but it will make a blade that will out-cut most of the other simple steels smiths use hands down. It really isn't fair to bash a steel when it could be the process that it is being subjected to that has the problems. I have always said- there is no bad steel, only wrong applications and poor heat treatments for that application.
 
Very comforting information. All past threads I have read stressing the importance of quickness to quench now have less meaning for me. Safe to assume, I suppose, industrial furnaces made to quickly drop the pieces into quench are only an added step in automation and have little to do with quality of heat treat.

RL
 
rlinger said:
Very comforting information. All past threads I have read stressing the importance of quickness to quench now have less meaning for me. Safe to assume, I suppose, industrial furnaces made to quickly drop the pieces into quench are only an added step in automation and have little to do with quality of heat treat.

RL
Click to expand...

The furnaces may have any number of reasons for that, the one I suspect the most would be simplicity, and letting the steel just sit around after austenitizing is never a good idea, unless of course you are normalizing ;).
All of the transformations that we are concerned about occur on cooling, and not much of that happens in the open air (well, not much cooling compared to a quench). If the trip to the quench was the critical part then we would have to conclude that 1095 somehow releases its heat in the open air faster than other steel, and I really don't think this is the case. It is all in the rate of cooling within a range that is entered a split second after super-cooling begins, or a minute or so after air cooling beings, in which case we are again normalizing and forming pearlite on purpose. In any case if you get a good efficient quench oil that is designed to handle problems like the 1095 curve, you can just relax and let the quench do the work. ;)
 
Once again ,Kevin,I agree totally.The proper quenchant and the wrong heat/soak are the cause of the bad results.
It's not how fast you do it.It's knowing what you want the steel to do!
 
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