Hi
@D_W, I’m sure my dear old Dad could answer your questions, but he’s quite elderly now and in poor health. He was a metallurgist who’s first job was at Rolls Royce working on engine metallurgy. He was one of the Concorde team and was on the maiden flight of 002. I must look out the ticket stub for that and sell it on eBay! I am ashamed to say that it all bored me rigid as a child, but I did enjoy playing with the electron microscope at RR. He moved on to making metal bits for helicopters at Westlands (back in the day we actually made state of the art helicopters in England). Then finished his career as foundry manager at Fabrique National, making a good percentage of the world’s armaments, but we’ll gloss over that. Anyway, long way of saying he’s probably forgotten more about metallurgy than most people ever knew and I’m happy to ask him if you have any interesting questions. Well to be fair anything post mid 80s he might be a bit sketchy on. He’s a bit frail, but still very much compos mentis and can still bore the hind leg off of a donkey about metal related stuff.
I've been fortunate that much of the complicated stuff in metallurgy doesn't apply to me (doing thermal cycling in a forge quickly instead of in a furnace in long controlled intervals), so I'm actually somewhat immune to metallurgists at this point!!
Larrin thomas (knifesteelnerds.com or something like that) wrote a wonderful book about high carbon steels (from a knife making perspective) and it's uber complex in discussion of potential problems (and then the person reading the book wanting to make use would want to know how to deal with them - as in - if you can reduce carbide size by forging complex steels, that's great, but the average person would have no way to roll or hammer M42 bar and heat it accurately to do it - those steels are very hard forging).
I thought maybe I needed to know those, but needed to do something different - harden and temper simple steels and experiment with thermal manipulation that shrinks the grain further and further so that I could match (or better in some case) hardness and toughness properties of well done steel.
The fortunate part is that the high carbide steels that may be better for turning and metalworking really aren't great for woodworking because they're not good at holding a fine edge - they're good at holding what's left after the fine edge comes off. That's fortunate, because the complex steels probably can't be done well in open air.
The other thing that I learned sorting through all of the data and charts is that most of the claims of edge life based on alloy choice are overstated (unless comparing a good sample of high cost stuff vs. a poor sample of low cost stuff), and that it's not feasible for small companies to actually have a custom alloy - instead, they look to be using something already established and calling it proprietary (or may have a mill make a melt for them and change an alloying element a trivial amount to claim it's proprietary - e.g., LV may have some slight modification to carbon in CTS-XHP, but there is no meaningful difference.)
Crown makes the same proprietary claim. To actually develop a new alloy would be extremely expensive. Larrin has done some of it as a hobby, but I believe he's relying on donated dollars to do the work, and he has a relationship with one of the powder metal makers (both stand to gain if he comes up with something great, so he's working in a way that crown or LV could not work - this is my opinion, at least).
The worst claim I've seen in all of the woodworking tools, though, is an ad for academy saw works blades from an australian retailer claiming that a $120 plane blade lasts 22 times as long as an ordinary plane blade. I did edge durability tests, and larrin has used a standard knife testing machine to do the same - M2 lasts somewhere around 70% longer than O1 steel - ASW blades are M2 at relatively high hardness).
I found a $11 chinese blade that's slightly short of M2 alloying elements (due to pinching pennies) that was 65 hardness and lasted 65% longer than a hock-equivalent O1 iron. The claim of 22 times longer is humorous, but not so funny if someone believes it and spends money that matters to them.
(and it's fair to say that if some of the turning tool makers spent the extra cost in getting M2 heat treated optimally, the cost of the lower end tools would go up).
The average shop woodworker could do a reliable test of edge durability for tools literally by spending about 10 minutes in a continuous cut on sample wood with one tool and then another, but maybe still come to a poor conclusion (if you compare a soft M2 tool to a hard M42 tool, you still don't know how much of the difference is hardness vs. alloy), and other simple things are ignored (e.g., the record power M2 skews aren't super hard, but they're not overly soft - the fact that they're in the middle makes them easy to hone on regular bench stones - so you can resharpen one in about 20 seconds and then turn for a while, and repeat. For that reason, I use them instead of the pro-PM gouge that I have - I would be averse to a 1 1/2 inch pro PM oval skew, but would hate to see what one would cost).
