I am struggling with a proper heat treating method based on the tools that I have available and can afford. What I have available is a gas fired forge with no temperature controller.
I started out using only O1 since I thought is was a good steel for knives and was easy to heat treat. After making quite a few blades I became aware of the proper heat treating methods and decided that I could not get a proper heat treat without proper temperature control and a proper soak period. So... no more O1 for me until I get a heat treat oven.
I am now using 1095 and I have invested in a 5 gallon bucket of Parks #50. I want to get the best out of the steel I am using with the tools I have at hand. Can you please give me some direction on how to get the best heat treat on 1095 using a gas forge with no temperature control and Parks#50 as a quench?
I am working hard to learn as quickly as possible, but there is quite a bit of conflicting information on the net. All I want is to do is to produce the highest quality knife I can.
I would like to sell knives at some point, but not until I know that the product I am producing is worthy of being sold. Any help/advice you can give me is greatly appreciated!
I recently received this inquiry and thought I would share it here to contribute in a very relevant way to this discussion. I also very much wanted to address this question because it would allow me to show that I am not down on or anti simple tools themselves, I am however against limiting ones knowledge and thus the possibilities for the future. This questioner is a fine example of a bladesmith who has the basic tools available to most serious smiths and still wants to maximize his results now and in the future. I will never refuse to help such an individual with any information that I can.
You have known steels, a forge, a bucket of excellent quench oil, and a desire to make the most of it, that is more than enough to become a really good bladesmith. The move from O1 is probably a wise one, O1 is too often recommended as a great beginners steel simply on the hardenability alone, however it is NOT a simple steel in comparison. I have worked with O1 a lot over the years and while indeed it will harden in almost any liquid, it has some particular heating requirements that cannot be totally met with just a simple forge. It will make a fantastic knife with the proper tools however it is as much as 3 times as expensive as 1095 or 1080, and with just a forge you may not be able to make a better knife from it, so why spend that extra money when you can get better results with 1080 or 1095?
There is indeed far too much conflicting information both on the net and in print. One needs to very carefully filter what they read. On the net there are legions of experts who just started this a few months earlier than yourself and they have spent a few more hours reading and misinterpreting as much as they can so they can paste it together and sound very knowledgeable in their posts. It gets a little more complicated in print when folks who have been doing it for many years but have really needed to learn little manage to use some impressive smoke an mirrors to make themselves appear to know what they are talking about. My advice is to VERIFY, everything including what I tell you, the charlatans will not do well against verification, I invite it with my information since sound industry practices and metallurgical facts are my friends and I have found the when you apply them correctly they really work.
Now for the 1095. 1095 tends to get a bad wrap for a couple of reasons, the first is that it is not 1084. 1084 has just the right carbon levels to make the most complete resulting phases and it also has the manganese levels to allow it to harden a bit easier. 1095 has lower manganese levels causing it to need a faster quench, but it also has an extra .10% carbon that needs to be dealt with in order to insure it is useful and not detrimental.
The ideal final condition for 1095 is a very fine martensite (the hard stuff) containing around .8% carbon in solution with the extra .15% in very fine carbides evenly dispersed throughout. It is possible to do this with tight heat controls, but in the forge we can come close by using prior heat treatments to set things up. The worst condition for 1095 would be low carbon coarse martensite with all the extra carbon separated out in the grain boundaries; a blade made of this would have lousy edge holding and still be rather brittle.
To get what we want we should start our heat treating in the forging, and watching our heats. Start hot and work cooler as you get closer to finishing. Normalizing will be important. Start hot in normalizing as well, 1700F is not too hot. Allow to air cool as quickly as you can, cooling quickly to Ar1 (where pearlite forms) will be important in not having extra carbon where you dont want it. Since 1095 is so simple all you have to do is cool below 1000F for good results. Believe it or not I have a large container of all kinds of old used oils that I use in normalizing. If you quickly quench into a sludgy oil just enough to turn the steel black and then reheat, you can refine things quite well without any carbon forming in the grain boundaries and not shock the steel by quenching from such a high temperature. For me the normalizing would consist of several cycles with the heat getting cooler every time. The final heat would be to just nonmagnetic and the quench would be all the way to room temp in preparation for the anneal.
Next take the quenched and hardened blank to a dull red glow but never allow it to go nonmagnetic, do this several times but always staying magnetic, if you go over it kind of takes you back to square one. When done, cool in air. This should take all of the carbon and put it into very fine globs throughout that will allow machining and other operations.
When it is time to harden your 1095 blade, you should carefully heat it to nonmagnetic and hold it there for just a second (this isnt really a soak but the attempt to hold will allow the temp to actually go slightly above nonmagnetic and achieve a good solution). Quench entirely under the surface of the #50 oil and keep the blade moving tip to tang as quickly as you can, do not just hold the blade still under the oil. If you wish to edge quench do NOT use the #50 as you will only ruin your investment in a good oil, get some cheap ATF (automatic transmission fluid) and ruin that with an edge quench technique. However I would also point out that there really is no strength benefits in an edge quench and the chances of fine pearlite at the edge are significantly increased.
As soon as the blade is down to the temperature of the oil, get it into a tempering oven preheated to at least 350F and heat it for around an hour. The actual tempering temperature will depend on your desired final hardness and how things worked out in the hardening heat. 400F normally makes a very good knife with 1095.
If you wanted to play with interrupted quenching and other techniques you should find plenty of information on that with a search of these forums. But this should give you a blade if fine gained 1095 that will only have pearlite at the very spine and a very nice carbide dispersion with good hardness. If properly done it should be able to slightly out cut a similar blade of 1080.
I always relish the opportunity to learn something new.
