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?