Do you see alloys like CPM Rex 76, and other highly alloyed mixes being a viable option in the future?
Do you think the difficulty in machining might cause them to be cost prohibitive?
I know it is Very hard (if not impossible) to speculate on materials that you havent used before, especially when they are as varied as steels go. Due to that, I wouldn't expect a solid answer, but more of an estimation.
Where do you feel the ceiling "might be"?
Do you think it would first be seen in cost in machining, or something akin to a cost/benefit ratio and your finding of a "sweet spot" in one or a few alloys?
I don't think it's much of an issue of cost benefit ratio on high performance knives so much as finding an alloy and heat treat for that allow that maximizes performance for an application. There is a tendency to say: if some is good, more is better and want to jam as much carbon and alloy and vanadium into the steels and this can ruin them if overdone. It's like making a good soup, too many ingredients and too much salt ruins it. Look at S30V. 4% vanadium? 14% chrome? 1.45% carbon (that's a lot)? Hell, it's only 3/4 iron, it's no wonder it won't hold together in a knife edge. Then look at something like Infi: .3% vanadium, 8% chrome, .6% carbon. He didn't get that the level of performance by packing it full of ingredients, he chose the right alloy, made the right tweaks to it and optimized a heat treat for it. Other steels like 3V start adding some abrasion resistance to the mix at the expense of edge stability so they hold up longer in some applications but not others. Going beyond 3V you can get further gains in abrasion resistance but might start seeing actual edge retention go down due to stability problems in normal use. So finding the "ultimate steel" is always a fun quest but I don't think the answer will be some extreme alloy that's almost unmachinable.
Interesting true story:
A company my shop does work for was modifying a Kevlar fiber cutting machine design used processing jackets in the fiberoptics industry. The carbide blades were good for 10,000-15,000 cuts but were very expensive. I made blades out of D2 with the goal of saving money and we were hoping to see 4,000-6,000 cuts. With optimized D2, by the time we were done with it, we were getting 250,000 cuts from D2 blades. This is an example of the right alloy with the right heat treat outperforming a "super material" by a factor of 20. Finding the ultimate material for that application wasn't a matter of cost/benefit ratio, it was a matter of material selection, engineering and optimization. The fact that it cost less ended up being incidental.
We're working with CPM 4V right now. It has a pretty hard sweet spot and the large amount of well distributed fine carbides actually contribute to a higher compressive yield strength. That and the moderate chrome content help it achieve edge stability you wouldn't think possible on such a high alloy steel (It's about 85% iron) . At HRC 63-64 it will have longer edge retention than 3V in most applications. Surprisingly this includes rough use. We looked at the industry standard HT for it, variations of that and the HT provided by the best HT shop in the industry. We looked at tweaks we've applied to D2 and 3V. We've looked at a lot of stuff and have really done our homework. When we started we had a hard crumbly edge that wore well in cardboard but turned to dust in impact on knots in wood and other use that stress the edge. By the time we were done with it, a thin pattern (our 3" EDC) at HRC 64 can cut a 16D nail at 18 DPS with little damage. I'm not sure that a higher alloy and more difficult to machine material would outperform it.
So, all of that said, I don't think the answer to the "holy grail" is in more extreme alloys, I think it is in finding the right alloy and giving it the right treatment.
