Anneal advice

Roger

Well-Known Member
I'm having a hard time softening up a piece of hand forged 01. After forging I can't seem to get the blank soft enough to drill a hole in. When I made the blank I left it in the forge overnight to cool down. After having problems with it being too hard I again heated it up then left overnight in a can of clay cat litter. Still way to hard, ruined bit #4. All the heating was done in the forge. Should I put it in the heat treat oven and try that?

Thanks.
 
try heating it up agian to non magnetic and put it in vermiculite. you can get it at most hardware stores in the garden section. i filled a small cooler with it and it works well. i have done this alot because i can never remenber to stamp my make before harding.:shush:
 
I would think that leaving it in the hot forge to cool should do the trick. If you are using a gas forge, get the forge hot and then heat the blade up to non-magnetic and then soak it for a couple of minutes being careful not to heat the steel over a bright red to orange. Then turn off the forge with the steel inside. Blocking the ends with fire bricks or pieces of ceramic insulating matting will help retain the heat. For a charcoal forge, get a good bed of hot coals going then bring the steel up to heat and soak then turn the air off and leave the blade in the coals until cool. You could also place the blade in a can of wet sand with just the tang sticking out and then heat the tang with a torch until it just starts to show color and then allow to cool. If all else fails you can get some carbide bits of the apprpriate size. Google up Carbide Connection; they have carbide bits in all sizes, even in metric, letter, and number.

Doug Lester
 
If you have a controlled oven you might consider normalizing and then doing a sub-critical anneal, AKA spheroidizing. You would have to look up the procedure for O-1 but it should involve heating to about 1300F. for a couple of hours and then either air cooling or slow cooling. This will give you the best machineability, but you will have to use tool wrap or anti-scale compound to prevent decarb.
 
Something just crossed my mind as I was doing a little lite reading before turning out the lights. Are you quenching the tang? If you are, that could be your problem. Try holding the tang out of the quenchant until it looses color and then cool it.

Doug Lester
 
Doug, it isn't during heat treat but when I just let it cool in the forge (anneal?). Last night I put the blank in the vice and started bending and it snapped right in half, no bending. Before I tried bending it I noticed some cracks along what would have been the spine and the blade. I'm new and probably too full of questions but here goes some more. I think I've been to impatient during heat treating and forging. Can working metal at too cold a temperature cause the cracking I saw? It was new material, O1 and I think I might have been hammering on it when it was too cool, is that possible? During heat treat and anneal I haven't been holding temperature very long. More like, "it's hot, quench". Should I be holding hardening temperature for 15-20 minutes? Would it be the same if I was annealing? I ordered Goddards book from Amazon but it won't be here till Monday and the weekend is coming. :)
 
Yes working the steel too cool, and sometimes too hot, can cause cracking in the steel. I'm at a loss as to why your blade seemed to have air hardened to that degree. If you just stuck the blade in the forge to cool after you were through forging it I would have expected it to cool slowly enough to form pearlite but it seem like from what you're saying that it formed martinsite if it's too hard to drill and snaps without bending. Are you certain of the identity of the steel? Admittedly, I haven't worked with O1 before but something really doesn't sound right here.

As far as how long to soak the steel, I would say that 2-3 minutes should be fine to get the carbides to disolve and release their carbon into the austinite. Watch the heat that youi apply to the blade. If it starts looking too bright, like going past organge, just pull it out of the forge for a couple of seconds and stick it back in when it starts looking red again. Without a programable oven, that's about the best you can do to control the heat. You also might turn the gas to the forge back juat a little. The tungsten in the O1 will help retard grain growth but you still have to watch overheating.

Wayne Goddard's book is fine to start with. A more advanced one that you might want to look at is "The Complete Bladesmith" by Jim Hrisoulas.

Doug Lester
 
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Thank you sir. I do have a programmable oven I built and the temperatures are accurate as measured with two different meters and thermocouples. The O1 I'm using came from McMaster Carr and is marked as such. I think I'll put it way aside and work with the 1095 I got from Aldo until I have enough practice. I really want to forge anything I make but I'm trying to learn two arts at once and don't have enough cranial capacity for that. I think I should just worry about making a good knife from existing flat bar, then tackle the forging part. Thanks again everyone for the input.
 
Hi Roger,

I'm no expert on forging but I've often heard it said that O1 isn't the best for it. Probably best to leave the O1 for stock removal. :)
 
I have worked O-1 for many years now and have learned to deal with its many quirks. First of all, a spheroidizing treatment has been suggested and that is a good idea, it is your annealing practices that are causing quite a bit of your problem. With steels over .8% carbon heating above critical and then allowing a very slow cool gives any carbon over .8% a chance to gather up and get into trouble, it will sheet up and makes drilling impossible but even worse it will also gather in the grain boundaries and weaken the steel toward the brittle side no matter how soft you may want it.

If the cracks you noticed were like a surface crazing running along the length of the spine almost appearing as if the inside swelled and cracked the outside, I know that issue very well and it is rather common with O-1. This is a result of overheating and allowing to cool all the way to room temp from this overheated condition. O-1 is a deep hardening steel, if you enlarge the grains and increase its hardenability even more, if you cool without cycling to refine the grain the outer surface will harden so differentially from the inner mass that it will be like a skin splitting over an expanding core, this is why it will not happen at the edge but be worse in the thicker areas.

O-1 must be stepped down from any heats above 1600F, just cool until the magnet begins to stick at around 750F-800F and then reheat until it just loses magnetism again. Just one cycle can save you a lot of heartache where those cracks are concerned. As for the anneal, forget all the forge cooling, wood ashes, vermiculite etc... save them for steels with lower carbon contents. After forging, cycle down and then reheat for multiple cycles in the range of red but still magnetic (around 1300F), or, if you have a rampable kiln, soak for 45 minutes at 1375F and then cool no faster than 50F per hour. The first should get you little spheroidal carbides that will give you no trouble, but may still be a bit tough at times, the second will definitely spheroidize the stuff enough to do any machining that you like.
 
Kevin, you know exactly what I experienced and now I know why. Great information. What would be a better steel for blade forging by a beginner, something more forgiving and with a lower learning curve maybe?
 
O-1 is a really good steel but it was designed to get very hard very easily without a lot of thermal activities like forging, it was made with quick stock removal and heat treatment in mind. It is this hardenability, the same thing that has most people thinking it is an "easy" steel, that causes most of the issues for forging. Look for lesser alloying, the rules are really easy, the simpler the steel the simpler the tools required to work it, it is for this reason that on my lists for steel selection I always include the tools available to work the steel with as a major consideration. Spending 3 times as much on an alloy steel that you can only tap 60% of its potential with simple tools is just wasted money. Of you still like the high carbon thing W1, W2 or 1095 will work out easier with forging and less sophisticated heating tools. If you want to go to the simplest of all 1075, 1080 or 1084 are the simplest of all steels available today, no funky alloying or extra carbon to give you grief and yet they can reach the maximum hardness you would want in a knife. Without all the other alloying you can heat these steels to any temp you want and just walk away without worry about them self destructing.
 
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