D2 is practically stainless. Maybe you’re thinking of something else.
HAP-40 vs. ZDP-189 vs. R2 ????
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It's highly dependent on the finish. In the pocket knife world it's pretty well regarded as one of the lowest grades of steel there is. I personally have had bad experiences with it. It is less stainless than even some straight up tool steels like cru wear.... for your reference: How Much More Chromium Does D2 Need to be Stainless? - Knife Steel Nerds " So the status of D2 as being the high corrosion resistance “semi-stainless” is perhaps overblown. It has about half of the chromium in solution as stainless steels and there are several other tool steel options with better corrosion resistance. "
Steampunk
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Every steel has its place. The balance is in between strength/stability (Ability to support very thin geometries, and how close to zero the edge can get.), its edge retention (Sometimes this is hardness to resist deformation when chopping, sometimes this is acid resistance, sometimes this is wear resistance.), its failure modus (Chipping vs. folding, and how you are prepared to repair either.), and its grindability (How easy it is to shape/reshape. Part of this relates to manufacture/thinning, and how easily the steel is ground, which can be eased somewhat by san-mai/laminate construction. Part of this is due to deburring, where slower to abrade steels can actually - sometimes - be a little more controllable to deburr, providing they aren't too plastic/tough. Grindability also is a factor of the abrasives you have at hand to grind/sharpen the steel with.).
HAP-40, ZDP-189, and R2/SG2 are all in that class of 'Super Steels'. They are hard to grind (Especially using more 'primitive' abrasives. HAP-40 in particular really requires diamonds or CBN.), lose stability/integrity/toughness in epic fashion when ground to a true zero edge, and are expensive to manufacture, and even more expensive to form by the maker into complex geometries for the best cutting potential. You can get amazing edge life from such knives, but at the cost of some things that are also appreciable in kitchen knives (Thinness BTE, complex geometry, cost, and ability to be maintained with a wider variety of simpler/cheaper abrasives or sharpening tools.).
HAP-40 really needs diamonds, but out of all those listed, takes one of the most wicked edges I've seen on any steel. Providing you don't grind it to the point of edge failure, it's also fairly tough. It can't be ground quite as thin as some steels with lower carbide volumes, but it holds an edge very well, even against a moderate quantity of food acids and abusive cutting techniques/bad boards. It's a steel that - if you cannot touch-up mid stream - will get you through a crazy day, doing shady stuff. It won't be your best cutter since you can't make the geometry as extreme as some steels, but it will have your back like a Marine. You really have to have diamonds or CBN to sharpen this stuff. Maybe SiC, but it doesn't feel as sharp. AlOx is a losing game.
ZDP-189 is an interesting steel... It's got all the limitations of D2/SLD, but it's been injecting steroids. Doesn't take a real toothy edge at a given grit, hard to deburr, can't be ground real thin, isn't fully stainless (It's stainless enough, honestly, unless you truly neglect your knives.), and is a nightmare to grind/sharpen/thin. However, it has stupid crazy edge retention/stability, providing the geometries are somewhat thicker.... I'd take HAP-40 as being potentially the better cutter (You can grind it just a little bit thinner, it's a little easier to deburr, and it takes a lot toothier edge.). However, I'd maybe take ZDP-189 in terms of outright edge retention if all you have are good AlOx stones (Cerax seems to do best for me.). Even naturals can sometimes work on the stuff.
R2/SG2 is in a little lower class compared to the other two, but not in a bad way. It's not as easy to deburr as HAP-40, and isn't as tough, but is much more stainless. It can take a toothier edge than ZDP-189 (Still not as toothy as HAP-40, though.), can be ground a little thinner, and is a touch easier to deburr (It's still pretty challenging.), but doesn't last as long, and is - in a weird way - slightly less responsive to AlOx or natural stones than ZDP. Edge retention isn't in the league of the other two, but it's still higher than just about any other steel used by Japanese knife makers.
If I had to work in a commissary, soup kitchen, etc, I'd probably pick up one of the cheaper HAP-40 offerings to get me through the shift. Alternatively, a simpler/mid-hardness steel, with an F.Dick rod. Both philosophies can get you through some crazy stuff.
There are some great performing R2/SG2 offerings, like Takamura, but they're really better suited to home use IMO. They're on the ragged edge of needing diamond stones, are kind of fussy to deburr, and a little on the delicate side.
ZDP-189 knives are a bit thin on the ground these days, but I guess if you like how SLD behaves, ZDP-189 is a sort of 'Super SLD', and worth a look. It's probably the absolute most wear-resistant steel you can buy, that you can still sharpen on some natural or AlOx stones.
That said, simpler alloys can typically be ground into thinner/more complex shapes, that can cut food with greater ease, are simpler/cheaper to manufacture/purchase, and can be maintained in less time with more primitive/cheaper/more enjoyable tools. This is often a worthy trade-off, even today, in the era of some truly incredible super steels.
HAP-40, ZDP-189, and R2/SG2 are all in that class of 'Super Steels'. They are hard to grind (Especially using more 'primitive' abrasives. HAP-40 in particular really requires diamonds or CBN.), lose stability/integrity/toughness in epic fashion when ground to a true zero edge, and are expensive to manufacture, and even more expensive to form by the maker into complex geometries for the best cutting potential. You can get amazing edge life from such knives, but at the cost of some things that are also appreciable in kitchen knives (Thinness BTE, complex geometry, cost, and ability to be maintained with a wider variety of simpler/cheaper abrasives or sharpening tools.).
HAP-40 really needs diamonds, but out of all those listed, takes one of the most wicked edges I've seen on any steel. Providing you don't grind it to the point of edge failure, it's also fairly tough. It can't be ground quite as thin as some steels with lower carbide volumes, but it holds an edge very well, even against a moderate quantity of food acids and abusive cutting techniques/bad boards. It's a steel that - if you cannot touch-up mid stream - will get you through a crazy day, doing shady stuff. It won't be your best cutter since you can't make the geometry as extreme as some steels, but it will have your back like a Marine. You really have to have diamonds or CBN to sharpen this stuff. Maybe SiC, but it doesn't feel as sharp. AlOx is a losing game.
ZDP-189 is an interesting steel... It's got all the limitations of D2/SLD, but it's been injecting steroids. Doesn't take a real toothy edge at a given grit, hard to deburr, can't be ground real thin, isn't fully stainless (It's stainless enough, honestly, unless you truly neglect your knives.), and is a nightmare to grind/sharpen/thin. However, it has stupid crazy edge retention/stability, providing the geometries are somewhat thicker.... I'd take HAP-40 as being potentially the better cutter (You can grind it just a little bit thinner, it's a little easier to deburr, and it takes a lot toothier edge.). However, I'd maybe take ZDP-189 in terms of outright edge retention if all you have are good AlOx stones (Cerax seems to do best for me.). Even naturals can sometimes work on the stuff.
R2/SG2 is in a little lower class compared to the other two, but not in a bad way. It's not as easy to deburr as HAP-40, and isn't as tough, but is much more stainless. It can take a toothier edge than ZDP-189 (Still not as toothy as HAP-40, though.), can be ground a little thinner, and is a touch easier to deburr (It's still pretty challenging.), but doesn't last as long, and is - in a weird way - slightly less responsive to AlOx or natural stones than ZDP. Edge retention isn't in the league of the other two, but it's still higher than just about any other steel used by Japanese knife makers.
If I had to work in a commissary, soup kitchen, etc, I'd probably pick up one of the cheaper HAP-40 offerings to get me through the shift. Alternatively, a simpler/mid-hardness steel, with an F.Dick rod. Both philosophies can get you through some crazy stuff.
There are some great performing R2/SG2 offerings, like Takamura, but they're really better suited to home use IMO. They're on the ragged edge of needing diamond stones, are kind of fussy to deburr, and a little on the delicate side.
ZDP-189 knives are a bit thin on the ground these days, but I guess if you like how SLD behaves, ZDP-189 is a sort of 'Super SLD', and worth a look. It's probably the absolute most wear-resistant steel you can buy, that you can still sharpen on some natural or AlOx stones.
That said, simpler alloys can typically be ground into thinner/more complex shapes, that can cut food with greater ease, are simpler/cheaper to manufacture/purchase, and can be maintained in less time with more primitive/cheaper/more enjoyable tools. This is often a worthy trade-off, even today, in the era of some truly incredible super steels.
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I mean regardless of all that it’s still pretty much stainless. I regularly leave my SLD out for an hour and there’s no patina or rust at all. Granted it’s a mirror finish but I feel like “rusts the second you look away” is pure hyperbole.
Get a Kaeru stainless, then let’s chat. Whatever Maxim is calling SLD.. is wicked.
I really enjoy my Sukenari ZDP189. Specifically because it's pretty effort-free, so it's on the mag strip that kids or girlfriends can use without me having to hover over them to make sure the blade is properly treated after use. Nobody touches my Kato or my honyakis - I don't trust anyone but myself to take care of them sufficiently. Anyone can grab the AEB-L, ZDP or SG2 knives.
The Sukenari HAP40 I had was pretty much stainless during my use. I've had 2 ZDP-189 and the one I used more often did get the most of core steel discolored.
Luftmensch
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Exactly this
. I have a Gihei ZDP189 knives. They are nice because, for the most part, you can take the knives for granted. They are sharp when you need them and they dont rust if you look at them sideways.ZDP189 is not god's gift to steel. But I think this whole stainless 'issue' is making a mountain out of a molehill. Im prepping food in a sterile environment and cleaning up afterward... I'm not skinning elk, in rivers of hydrogen peroxide! Maybe ZDP189 is a disappointment if you are into survival gear or scuba-diving - but that is not what KKF is about.
For the little that it is worth... the vendor who sold me my knives stressed that they were semi stainless.... and in the several years I have had them, they have been pretty much stainless. Ironically, it was KKF that 'told' me that ZDP189 was 'stainless'.
I’ve been using a sukenari Hap40 lately and it’s been great. So far pretty close to stainless. Edge holds up great on poly boards. Haven’t sharpened it yet.
