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  #16  
Old 02-17-2017, 07:39 PM
jimmontg jimmontg is offline
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Been a long day. Just read all the above. I have never had a problem with O1 warping either except I either ground it too thin or I had a bad batch and I have had a bad batch. I've had bad D2 as well with bubbles in it.

I never buy precision ground O1 and not just because it's more expensive. 5/32 pg O1 would be ground from 1/4 sheet or mill flat bar, worst would be from 3/16 sheet. No problems if from bar, but if from sheared sheet then there can be some twisting stresses from the shearing operation not very discernible after grinding and it will show during heat. The fact that you had a piece that warped while in equalize temp tells me this. A fully ground blade should not warp at 1200 degrees. You can take the one that warped at 1200 and straighten it out. The others would have to be annealed and then straightened. Do you have an arbor press? You can make a bolt together hydraulic press using a bottle jack by the way.

If the piece you do in the forge warps it's the steel, if not then it's the oven. Also I presume you grind your knives evenly and do not create much heat when you're grinding as uneven grinding will also cause warping.
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  #17  
Old 02-18-2017, 06:54 AM
WBE WBE is offline
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How are the blades set and supported in the oven? If they are too close to a coil, they will warp. OK, I have been HTing 01 for over 15 years. If I do not do a separate stress relief, my blades warp, and sometimes even then slightly. Per Kevin Cashen's advise, and advise from Robert Cella years ago, I stress relieve for an hour or longer, after the temp reaches 1200. I do this the day before I do a programed HT, and also coat the blades with ATP641 for decarb protection. I start the main HT with the blades mounted edge up in slotted fire bricks, in a programed cold oven, and it preheats the blades at 1250 for 30 minutes, then goes on up to 1400 for 15 minutes, which is done only to let the oven catch up and equalize. Then the temp goes up to 1475 for a 20 minute soak before quenching in 130 Parks AAA oil. I will add that my blades are finished ground and polished to a 220grit surface before HT. My Evenheat oven does not over shoot temps. It under shoots, and takes as much as 10 or so minutes to level out in the upper temp ranges. If you never ever get at least slight warping with 01, you are running thick unfinished blades, or you're just not trying hard enough. 01 can be hand straightened for about 6 to 8 minutes out of quench, and with some blades as long as 10 minutes out. Stress relieving greatly reduced my warping problems, but I've never had blades warp in the oven. Only in the quench.
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  #18  
Old 02-18-2017, 07:23 AM
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I agree with WBE on this one.
Do have a question w/suggestion - try placing two blades in side by side, one edge up and on edge down. If they both warp in same direction then it's most likely heating element differential. I have always blamed severe warping as a failure on my part to make sure all is "even" prior to HTng. Minor warpage does occur frequently with O1 and the thinner the cross section the more likely it is, for me. Just can't see it being the steel if you have run stress relief cycles.

Since I forge all my blades I have made it an automatic practice to stress-relieve each blade both after final forging and after final profiling. Maybe more habit than necessary for most forgable steels, but not a big issue as part of the process time wise and I don't have to step back and wonder if I did or didn't...it's always did.


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  #19  
Old 02-18-2017, 10:01 AM
jimmontg jimmontg is offline
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Most of us do not finish grinding our blades before HT. I do mine as directed by most professional heat treaters, about 80% finished and finish grind after full HT.

Now WBE says he finishes his blades before HT to 220 grit. I understand the separate equalize. Some makers do that. I also know that Cashen knows more about HT than I do, but I also was a heat treater and what I am specifying is by the best practice and book. No pro HTer would HT finished blades the way WBE does without charging extra for them or say not responsible for warp. I have probably checked and straightened as many HT parts as anyone here, but I never heard of doing them straight from quench, they would be hard as a file or harder or on it's way and I wouldn't relish having a blade pop apart in my press. I always straightened knives after final temper, but my blades barely warped if at all. D2 could be bad about it, but not O1. The only time I had a problem with O1 was when it had been precision ground from too thin of a sheet, ie. .250. Should be ground from mill bar stock or 3/8" sheet. 1/4" is too thin period. I will buy 3/16 sheet O1 and straighten it before grinding it and mill bar stock as I do not know what I am getting under that precision ground stuff unless I know the manufacturer.

So poor Irishknifeworks is getting contradicting information. O1 not ground enough before HT and O1 ground too much before HT? Oh and some makers do not grind anything but the profile before HT. What the heck?

I stand by what I said above, if your 80% ground knife warped during equalization @ 1200 either the steel is bad and I seem to be the only one to have encountered it, but it was a machine shop and they bought the lowest priced stuff, but it was 4.5mm x 50mm x 4 ft. PG for paper cutting blades, stuff warped before machining in equalize. Sent it all back, 200 parts cut to 120mm and the supplier is not responsible for wasted labor. Pro heat treaters are same way, they will just replace the material if it's their fault.

Other option is your oven is heating unevenly. Those are the 2 options unless your idea of 80% finished is different from mine, but it still shouldn't warp at 1200.
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  #20  
Old 02-18-2017, 10:31 AM
jimmontg jimmontg is offline
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WBE, I am going to try your method for O1 as having the blade 100% ground is preferable to grinding hardened steel which is OK if you have a wet grinder. How thin of material do you grind like that, down to 1/8" WBE?
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  #21  
Old 02-18-2017, 11:31 AM
samuraistuart samuraistuart is offline
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"If you never ever get at least slight warping with 01, you are running thick unfinished blades, or you're just not trying hard enough."


Can you expand on this statement...why you think this is the case? I buy PGO1, never thicker than .110", bevels always cut prior to HT, edges at .020", 120 grit lengthwise, ATP641, placed into prewarmed kiln (never ramping from a cold kiln as this does no favors to aus grain or decarb if unprotected), nor do I employ a pre soak at any temperature. I also quench in Parks 50 oil with O1, an oil that is technically too fast for O1, and I have never had O1 "warp" or "bow", or God forbid "corkscrew" on me. I'm getting 65-66 post quench, and have to temper at 425F just to get it to 62-63. There may be some extreme small amount of distortion that I do not detect, that gets ground even post HT.

Other steels that are not PG, like 1084, W2, 52100, I get some small amount of distortion. Hitachi Blue and white san mai with iron jackets usually will warp to some degree. I have used a 1200 stress relief on these steels that does seem to help...not always. But I am always surprised at O1...it has always been extremely stable for me, even in a fast oil quench. Same with O7 from Germany....stuff stays very straight. Maybe not dead nuts flat as it was pre quench...but distortion that is basically undetectable by eye, ground off during post HT grinding. I'm guessing that is what you mean, and I agree. There is some distortion that goes on during quenching....it's a matter of physics, and no way around it. But O1 for me, it's LACK of distortion, surprises me. There is nothing to straighten during MsMf, nor tempering.

Last edited by samuraistuart; 02-18-2017 at 11:37 AM.
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  #22  
Old 02-18-2017, 01:32 PM
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Ray Rogers Ray Rogers is offline
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Clearly different strokes for different folks on the subject of O1. What's really amazing is that we apparently all get good results no matter what process we use. That may be more of a testament to O1 than to our heat treating

FWIW, I just follow what Latrobe says to the best of my ability. There are many different data sheets for O1 online and they aren't identical but they don't differ greatly as far as I have seen. Latrobe says heat the steel slowly, no more than 400 F per hour. Well, I start with a cold oven and it heats slowly but faster than 400 degrees per hour. Latrobe says nothing about pre-heating the oven. Then they do the 1200 cycle and then up to 1475, the process most of us seem to follow. I think the details of most 'official' O1 data sheets strongly apply to complex parts but are much less critical for simple blades.

My oven is flooded with argon to limit the scaling. Grinding post HT eliminates any scaling that does form. I grind bare handed on fresh ceramic belts with a bucket of water to dip in when the blade warms up. With a fresh belt I find grinding a hardened profile to be only marginally more difficult than unhardened steel although it takes a little more time. I do this routinely with 3/16" and thinner blades but would do some of the grinding before HT on anything thicker.

All of this is not to change anyone's mind about how they do their O1 but I did want to provide the details of my process and why I do it that way ...


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Last edited by Ray Rogers; 02-18-2017 at 01:53 PM.
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  #23  
Old 02-18-2017, 03:19 PM
jimmontg jimmontg is offline
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Talking

Hey Stuart, I'm in your camp, I've never had O1 warp on me except the example I gave above. My very first O1 knife I made was a 3 blade Pig sticker set. One for killing the pig, allowed in OK, and two for skinning and dressing out, all 3/16 PG O1. I completely ground them and sanded down by hand to 220. I had a 3x21 belt sander clamped to a table. Worked remarkably well until it blew up from metal chips. (Newbies take note for cheap grinder and what will happen if you don't keep it blown out.)

Ray you are right as well, but the Irish Knifemaker is having some probs he shouldn't. Something's wrong. I'm inclined to think bad batch as his one blade warped at 1200 and that shouldn't happen, even with some uneven heat, a lot yes, but not a non perceivable amount. I mean who has precise even heat in their forge?

Oh, back to where I was, I took my knives to the old Hinderliter HT in OKC and the rep said they couldn't guarantee they wouldn't warp because they were finished. Only the edges were a little wavy after HT and I just reground them.

I learned a tremendous amount of knowledge from Hinderliter and they are still there, but actually a different company now, but they will still give you some advice, but not like they used too. I've always kind of gone by the book on O1 except the per inch rule for knives. Hinderliter taught me how to do D2 with nary a single failure. I still have some D2 blades left from when I worked at my last job, Precision Products of Asheville. Including a 3/32 filet knife in my photo album. A flexible D2 knife.

Triple temper for D2, not exactly a secret. Cryo between tempers, never before temper. The temper before cryo also gives you time to get your whole batch HT & quenched, like several hours. I have had O1 crack when I went straight to dry ice from quench as well so temper O1 first too.

A 400 temper for one hour for O1 and then 3 days under dry ice and temper at 450-65 for 2 hours min. 425 for D2, 90 mins. and three days dry ice, 450 for 2 hour, three days dry ice and 425-475 for 90 to 120 minutes depending on what you want for final hardness. My blades lie directly on one block and after I put all the blades I'm doing on I put another block on top, one even layer. My ice chest I built from styrofoam, four inches thick in all directions.(Lowes sells 4' x 8' x one inch thick sheets) No diesel, it isn't necessary for flat blades. Dry ice will last almost 2-3 weeks if you keep it shut. My machine parts tank was stainless lined and diesel and acetone and dry ice mixed, sounds safe don't it?

Why am I saying all this you may ask? Because O1 and D2 are the steels I have the most experience with hands down and somebody with a HT oven offered to HT my knives LOL.. If I was allowed a forge where I live I would HT nothing but O1 and forge Damascus and 1050 or 4140 plus 15N20 for axes. Dry ice is $1.19 a lb.

For D2 LN is better than dry ice, but dry ice is cheaper and will still accomplish what I want and for D2 it's not hardness as much as toughness. D2 is tricky, toughness must be in the HT or your blade cracks a year later. Hinderliter taught me that and reading a knifemaker I cannot remember his name now except he was called Mr. D2. When I started making knives there were mostly tool steels and 420- 440C and ATS 34, CM 154, which was inconsistent then.

I buy O1 barstock or sheared sheet. PG is too expensive. I remember when CPM 440V came out. What do they call it now? S30V or something?

I am seeing something here I have not seen since I had that bad batch of O1 in the machine shop. An unfinished blade warping at 1200 degrees made from O1? The Irish maker HT three old blades that did not warp. Does that sound like uneven heat? Sounds like bad batch or worse, mis-named steel. I have had more mis-marked steel than bad batches. Irish maker, how hard are these warped parts?
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  #24  
Old 02-18-2017, 03:53 PM
WBE WBE is offline
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I do a lot of 3/32", occasionally 1/16", some 1/8", and up to 1/4" at most. PG 01 in bar stock.
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  #25  
Old 02-18-2017, 04:23 PM
WBE WBE is offline
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I learned about the post quench hand straightening 01 from KC years ago. He has stated that he has done it as much as 12 minutes later. The sooner the better, but it is very submissive for the first few minutes out of quench. A little too hot to be comfortable bare handed, but fine using a dry rag. In fact, it is easily over done, and subject to reverse the warp, and then have to bring it back to straight before it does set. It's not magic. 01 is just slow to get to mf. I've never broken or cracked one. With thin stock it is almost too easy.
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  #26  
Old 02-18-2017, 04:44 PM
jimmontg jimmontg is offline
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WBE, you get O1 1/16 in bar stock? I never used less than 3/32 and it was sheared and you HT the way you described? Amazing stuff O1, like Ray said it's one of the best steels around. Guess it is why it is my favorite steel, oven or forge. I do not say so usually on the open forum, but I tell newbies to forge HT O1 before 1084.lol It has flexibility too and does well in a forge. To say 1084 is better may be so, but O1 does pretty good too. Please note HT O1, not forge it.

WBE I never had anyone tell me that I could form O1 and get rid of the warp after quench. I presume as you said it has so much time to be shaped. I could tell you some stories about HT cuprous and aluminum metals that last 2 to 3 hours before it goes back to hard. Beryllium copper makes outstanding springs and even firing pins. I used to make springs from it.

Last edited by jimmontg; 02-18-2017 at 04:51 PM. Reason: addition
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  #27  
Old 02-19-2017, 05:17 AM
WBE WBE is offline
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A2 can also be hand straightened from the time of being able to handle with a shop rag as protection, to about the same as 01. A2 is a great steel also, but too expensive for my liking, and the higher heat required in HT is uncomfortable when the oven door is opened. I don't use it, but have a friend who does on occasion.
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  #28  
Old 02-19-2017, 07:38 AM
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Ray - "Clearly different strokes for different folks on the subject of O1. What's really amazing is that we apparently all get good results no matter what process we use. That may be more of a testament to O1 than to our heat treating"
Pretty good lick right there.... seems no matter who, but us that love O1 will "make it work", just to good a steel to push aside.
Sam - got a lot of the same experiences with O1. I forge all my blades, just use the grinder for final profile clean up and sharpening, rest of time it's a handle shaper. I forge as close to finish as possible usually 90%+, because I can. As long as one pays attention to the final heats the results speak for themselves.

Never tried to post straighten a blade of O1 because warpage is rare (for me). I too use Parks 50, just cause it's right there and I also take the temper to 425 or the edge is just a bit too brittle.

This is all good stuff and I like what I'm reading here. Still don't know if we solved the original poster's problem. Do hope we didn't scare him off. Some times you just got to be standing there with them to figure out what's really happening. We often see the same thing just with different eyes and terminology. Science tries to make things more exact, but often gets "muddied" with subjective perspectives. Gotta love it.


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  #29  
Old 02-20-2017, 06:06 PM
irishknifeworks irishknifeworks is offline
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So here's an update. I HT the last blade from the suspected bad batch of steel in my forge instead of the oven. It warped there as well. So bad steel is a definite possibility. I've ordered more 01 from a different supplier.

I think I've ruled out any problems with the oven itself. It seems to be working fine with even heating. I've already mentioned that I HT a couple of older blades that were rejects. They HT just fine.

I can only think of one other possible explanation. I've used a full grind from edge to spine on each of these blades (something I seldom do). Possibly the stress involved on such a grind is causing the warp. So that brings up a couple of questions. Ray, you mentioned that you do your grinding after HT. Do you not risk messing up your heat treatment when you do that?

Also, if a blade warps, what's the best time and method to try and straighten it?
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  #30  
Old 02-20-2017, 08:15 PM
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Ray Rogers Ray Rogers is offline
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Not much risk to the HT with post HT grinding (quite a few people do it that way, not just me). I grind bare handed. The blades are tempered above 400F so to do much damage the blade would have to get hotter than that and my bare hands give out long before that happens. I dip the blade in a bucket of water every pass or two so it never really gets more than warm. Extra care is needed as the edge starts to get thin but using sharp belts and having a variable speed grinder takes the worry out of that too.

I've been told that O1 can be straightened at all kinds of times that I would never have thought to try. For myself, if I see warp before the quench I straighten it while there is still color in it using an arbor press I have set up for the purpose. If it warps in the quench then I usually do another temper and try to straighten while the blade is hot from the temper. If that doesn't get the job done, I have a straightening fixture that I clamp the blade into and then the whole fixture goes back into the oven for another temper. If needed, more torque is applied to the fixture and back in again, repeat until the warp is gone or the fixture is maxed out (in which case I'd toss the blade). One thing about grinding post HT is that blade's rarely warp, are easy to straighten if they do warp, and if it turns into a noodle all you lost was a piece of steel and 15 minutes of work profiling it....


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