peacefuljeffrey said:
See, a post like this just lets me know that I do NOT know enough or follow closely enough all the things you need to be aware of to make "the right choice" of steel for your knives.
You can avoid poor choices with fairly broad rules, in general the further you try to go the harder it gets because you end up with a bunch of things competing against each other and you have to decide which ones are more important and to what extent. As well in general, small refinements take way more work than the large initial benefits.
peacefuljeffrey said:
Well, it just appears to me that there haven't been such worthy differences found.
A lot of the advances are not for you and I but for makers. Steels which make it easier for them to do the heat treating or improve the finish. CPM-154CM for example is mainly for knifemakers who found S30V to difficult to work with, not that it makes a better knife for the guy cutting things.
Many times the advancements are trying to blend properties, 3V for example was an attempt to improve on the wear resistance of D2 and the toughness of A2 and do it all in one steel. S30V was origionally promoted as a stainless steel with tool steel toughness.
BG-42 combines the properties of high speed and stainless steels together. CPM REX 121 is essentially a carbide replacement for toughness failures, 72 HRC. The japanese are now working on high toughness powder high speed steels.
I want to know in a chart-and-graph sense just where improvements have been made in exactly what facets of knife performance, and also what tradeoffs have been made and what may have been compromised in the switch.
That would be useful indeed, it is pretty easy to find for tool steels, not so much for stainless. This is a complex question though, even if you narrow it down to edge retention and can't be reduced as trivial as is often claimed. Phil Wilson, R.J. Martin, Jimmy Fikes, Sal Glesser, Kevin Cashen, Jerry Busse, and Ray Kirk are all solid guys to talk to about knives and steel, a very high knowledge/hype ratio. Swordforums has a very informative forum on metallurgy, it does get complicated though, you need to have a basic background to follow some of the more technical discussions, a basic text like Allen covers most of it.
What I was saying in that post is that short of a gain of say 10 RC points in a very corrosion-resistant knife steel, why are we tinkering around so very much and being so incredibly fickle.
Corrosion resistance stainless steels at near maximum martensite hardnesshave been around for a very long time, ATS-34 can reach 65 HRC, most stainless steel are way under hardened because it requires high temperature austenization, aggressive quenchs and/or cold treatments.
When I still see knives in new steels listed at Rc 58 when I know I've seen others in older steels that claimed to be hardened to 60 or 62, I ask why we even switched. Can an improved, new steel be better at taking and holding an edge even despite a lower-than-the-last time Rockwell hardness?
Yes and no. Ease of sharpening depends on grain size, carbide distribution and hardness. Edge retention depends on strength and wear resistance as well as impact toughness. A steel can have greater wear resistance at 58 HRC than another at 59 HRC but have lower toughness and strength so it will be superior for some cutting and not others.
You can have a steel which works very well at a high angle (say 20) but then breaks apart at a lower angle (say 10) and then another steel which takes the lower angle readily and is now vastly ahead in a direct comparison. Now which one do you say has better edge retention? This is still just considering one medium cut in one manner and it can all change if you switch materials, method and grit finishes.
-Cliff
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