Interesting that you bring up this comparison, Kennethsime. I was just thinking about starting a thread asking for comments and comparisons on ‘real world’ use between CPM S90V and ZDP189.
I have both steels: ZDP189 in the Dragonfly, Caly 3.5 and Manbug and CPM S110V in the UKPK.
I’ve used and sharpened S110V a fair amount, but nowhere near as much as ZDP189, which I often use in my daily work, and have for years.
I don’t really think of the two steels as being that similar, despite both being high wear resistance stainlesses.
Well, ZDP189 is nominally stainless, although Larrin’s testing and analysis has demonstrated that for practical purposes it comes in below a true stainless steel, regarding corrosion resistance.
I have had orange surface rust form on ZDP189 from orange juice left on the blade and from being carried in lightweight shorts while cycling for hours on a hot day. The oxidisation in both cases either wiped or stropped off the blade, leaving no pitting.
CPM S110V is definitely more rust resistant.
With a modicum of care, ZDP189 doesn’t rust. One of the other advantages of ZDP189 is it takes a high polish, which helps somewhat with corrosion resistance.
As mentioned, sharpening S110V is a matter of starting with the right abrasives, like diamonds, CBN or SiC.
ZDP189 will take a really nice edge using standard alumina stones.
ZDP189 has a higher carbide volume at around 30% chromium carbide compared to S110V at around 27% of mainly vanadium enriched chromium carbides, vanadium carbide and niobium carbide.
ZDP189 has a higher attainable hardness, and performs well with both highly refined and coarse edges. CPM S110V seems to perform well in a 400-600 grit type edge, and can be hardened to around 61-62 Rc. Although ZDP189 can be hardened to around 67 Rc, I believe most of the Spydies in that steel are around 62-65 Rc.
I’d guess that CPM S110V is a bit tougher, but neither are really what you’d call tough steels.
As always, which steel is ‘superior’ for knives, really depends on what you are using it for.
I cut a lot of abrasive material like heavy industrial cardboards at work as well as heavy duty pallet strapping. I also need a fine edge for cutting plastic wrap etc. I don’t really need stainlessness, and I don’t mind sharpening or doing touch up refinement to keep a very sharp edge.
So ZDP189 is really my gold standard of high wear resistance stainlesses. For my uses it’s stainless enough, in that blades I’ve used for years don’t show any patina or rusting or pitting.
I prefer the way ZDP189 keeps an extremely sharp edge for quite a while. If I need more toughness I generally go to HAP40.
S110V is certainly an interesting steel, but that’s my opinion and personal preference on the two steels.
Larrin’s micrograph from Knife Steel Nerds
, of ZDP189 austenitized at 1850 F:
And CPM S110V austenitized at 2050 F: