O1 vs.D2 tool steel
Looking for better abrasion resistance. I've made some small tools for turning wood, or pottery, out of O1. The stock is 1/8" thick and 1/2" wide, about 10" long. I grind a profile on one end, chisel cutting edge, various forms, about 1" long, then bend it 90 degrees to the body of the tool -- so the remaining stock becomes the handle. The final form is an L shape, with a 9" body and a 1" leg (minus bend radius).
O1 takes these 90-degree bends very well. I grind a small neck in the tool and round the edges before I bend. Mount the tool in a vise, heat with propane torch, bend away. Then stress-relieve at 1400 degrees before hardening, tempering, and final grinding.
Simple question: will this work with D2? Can a 1/8" thick, 1/2" wide piece of D2 stock be bent 90 degrees and not crack/break? The cutting forces are not large, the tool is held by hand, the RPMs are low. But the material is abrasive -- the O1 tools wear a bit quickly.
A point to consider is that D2 will need to be got hotter by about 300-350 degrees F in order to respond to heat treat.
I recommend you use A2 instead of D2. Both A2 and D2 have to be hardened in an accurately controlled furnace,wrapped in stainless steel teat treating foil.
D2 is very brittle when it is hardened and tempered,and may snap off in your face for such a purpose.
I have made knives of D2,and have a Queen brand pocket knife made of it. It doesn't seem to hold an edge better than anything else,for some reason. Maybe I haven't found out the correct sharpening angles yet.
I don't actually use my D2 knives,as they are Bowie knives and show pieces. However,I carry the Queen knife daily.
I have used A2 for quite a few years to make punches and dies for our home business,and they stand up to several thousand cycles before they need grinding.
Be warned,you do need ACCURATE furnace control within about 25º to get optimum life out of your tools,and if any oxygen gets to the tools at hardening heat,you will get a soft skin on them.
CAN YOU make a tool holder,and use short pieces of HSS for your cutters? That would be the easiest way out.
I built a machine for winding toroid transformer cores from silicon steel, which eats cutters for lunch. It is one of the most abrasive materials I have tackled. After rolling up a core, the strip is shorn by what amounts to an air powered scissor. We originally assumed it would have to be carbide, but to expedite things I made a temporary cutter from D2. A year later, after countless cuts, it was still doing well. The customer asked for a spare set of blades, and for some reason I made them from A2. They dulled in days and I had to make another D2 set. These were vacuum hardened by Paulo Products, probably a bit expensive for you unless you can do a batch. The edge did not need to be razor sharp because the blades were held together by tight guides and the moving blade was curved so it was cutting at the optimum angle across the cut and was powered by a strong air cylinder. Nevertheless, I was impressed by the difference in performance. Probably part of the good performance of D2 was due to the heat treat by people who do it every day of the year with the best equipment. I doubt that anyone could match it with a hand torch.
Can't comment on the bending problem, but will agree that IME, D2 is above A2 for abrasion resistance, enough to notice. I've made a lot of A2 tools including irons (blades) for handplanes. Maybe a dozen years ago I made a few of D2. For my purposes, D2 was miserable to work and (surface) grind, and was not as "tough" as the CPM M4 I started experimenting with at the same time. My experience with the handplane blades (still have one in a #8 jointer) is that it can be "chippy" if the angle is too acute, but it gets as sharp if not more so than A2 and lasts longer. Again, I prefer CPM M4, though.
x2 on the suggestion about making a holder and inserting bits.....if it is workable.
D2 hardens all the way through, unlike O1. Resharpen abilities obviously increase. It is more abrasion resistant also. It is tougher than some people like to admit. It will take the bend before hardening. A2 is good also, and very similar to D2.
I've made lathe tools by silver brazing a piece of a HSS cut-off blank onto low carbon steel. M-3 worked great for me, even better is tantung, which is easy to grind but very tough stuff. I haven't found the heat of brazing to degrade the performance of the steel.
If your tool design allows it, this is a really easy way to get some very sophisticated tool steel at the cutting edge for next to no $$ and without the bother of hardening.
D2 IS more wear resistant than A2. It has much more chrome. The brittleness is what I wouldn't want in a wood lathe freehand chisel. Back in the 60's I made a very sharp skew chisel out of a file about 2" wide. I didn't draw it enough,and it instantly snapped off violently-as soon as I touched it to the wood. BARELY missed my face as it went past my ear at high speed.