ZDP-189 Corrosion Resistance - Compared

Nothing scientific, but I've found it to be the least corrosion resistant of the Spyderco steels I've carried or used. Specifically, it's the only one that's rusted without some degree of neglect. The others I've carried that I can think of would be S30V, S35V, 440V, VG-10, GIN-1, ATS-34, ATS-55, AUS-6, AUS-8, H-1, and MBS-26 (kitchen knives).

 

different.

it won't patina like D2 does (at least in my experience) but it will get small pits rather easy. keep an eye at the pivot area too, i've had some surprise under the washers on my stretch.

anyway nothing that alters functionality for actual use imho but as you asked ...

 

I have never had a problem with rust or corrosion with my knife in ZDP. I live in a dry home, and carrying the knife and using it for cutting string or opening boxes caused no problems. If 440C rusts for you, just about anything will.
I would expect that VG10 would do better than ZDP in terms of rust resistance.
I have used knives in 440C for freshwater and saltwater fishing and never had a problem with rust. I take good care of my knives, and make sure that they are clean and dry after use.

 

I think ZDP has more than adequate corrosion resistance. I work as an electrician in Houston where it is extremely hot and humid in the summer months. My work knives stay soaked in sweat for approx. 50 hours/week from May through September. I regularly carry either a ZDP Stretch or a ZDP Endura at work and haven't experienced any problems with ZDP rusting or pitting. The only maintenance these blades receive is wiping the sweat/condensate off of the blade every once and a while. I haven't experienced any corrosion problems with any Spyderco I have carried at work. From my experience ZDP is as corrosion resistant as VG-10, S30V and CTS-20CP. I know that this isn't an adequate comparison of corrosion resistance but from my real world experience this is what I have found. ZDP may rust if left out in the rain overnight but in daily use it is great. I can't think of a better test of a knife's corrosion resistance than my hot, sweaty pocket and ZDP passes this test with flying colors.

 

I have never seen any rust on my ZDP knives and I live in Florida which is pretty humid and spend quite a bit of time on the coast in the salt air.

The steel will get a little darker and on one knife you can see where the part of the blade that sticks out of the handle when closed is slightly darker than the part that is inside the handle. I guess this could be considered staining or even a patina. But it is such a slight change it is a non issue for me.

 

As Deacon suggests, ZDP is probably the least corrosion resistant of our stainless steels. The large amount of carbon eats up much of the chrome forming carbides and there is less than you'd think for corrosion resistance.

I carry ZDP often, but Colorado is a dry climate. Less corrosion resistance just means more attention. Generally "high performance" anything requires more attention.

sal

 

Thanks for the definitive answer, Sal.

I've EDCed my Stretch CF in all kinds of weather for about 2 years now without issue. I hit my all my knives with a silicon cloth every once in a while. That seems to keep everything copasetic even on my ZDP and CPM M4 blades.

 

live in hot, moist philippines and the zdp endura is my edc. not much problem, though i'm starting to see coloration at the notch/lock area of the tang. the exposed part of the blade when closed also is starting to 'haze' since i'm a sweaty guy and i carry the endura at my waistband. but nothing regular wiping and cleaning can't fix.

 

This thread has a real-world corrosion review for the ZDP Stretch over +- a year.

Apart from some expected corrosion on the blade under certain conditions, it seems like the SS liners also need some TLC from time to time.

http://www.spyderco.com/forums/showthread.php?40101-The-on-going-Stretch-2-review-thread-Day-1-A-Cursory-Examination/page2

See also pages 4 and 5.

 

I assume you meant 440C. Just a hunch, is that knife just a cheapo junk knife? It may not really be 440C, and thus is giving you a false requirement of needing something like H1. 440C is fairly corrosion resistant, I just do not see it starting to rust overnight. I only have one knife in ZDP-189 and it is a laminated steel (Caly 3), but has shown no signs of rusting.

 

I got a Spyderco Stretch in ZDP-189 about a year ago. I carried it one time on a bike ride and cliped it in the waistband of my biking shorts. As it was positioned, the top of the blade was in contact with my bare skin on my hip. At the end of the ride I took it off and found that a lot of my body sweat covered the blade. I wiped it off, but the next day I found that I had about an 1 1/2" line of tiny rust pits on the blade. I tried rubbing them off with Flitz but they wouldn't budge. I sent the knife back to Spyderco for a sharpening and hoped they could buff out the pitting, but they didn't. I thought with chromium content of 20 that I wouldn't have any problems with rust...guess I was wrong. Just my 2 cents.

 

ZDP has 3% Carbon and with the HT and Tempering process to get it to the very high hardness range most of the Chromium is formed into Carbides so it will be less stainless than steels like S30V.

 

I've found ZDP-189 to have decent resistance corrosion, but nothing stellar. I just dab some oil on it now and again and quickly wipe it off. It'll rust pretty hard if your not careful. With that being said no steel is perfect and I'd say for its intended purpose ZDP-189 has left a positive impression on me.

 

My ZDP Delica behaves very well WRT corrosion since I gave it mirror polish. Plan is to do the same with my ZDP Stretch someday. I live and work on land but close to the ocean.

 

I can tell you first hand that ZDP-189 has very little resistance to food acids. Tomatoes in particular will wreak havoc on your ZDP blades. I found that out the really hard way about 3 years ago. It not only corroded badly but it was as if I had subjected it to a brutal acid bath of sorts. Anytime you use a ZDP-189 blade on food you had better wash, rinse and/or give it a thorough cleaning if you want to prevent severe corrosion.

But performance wise ZDP is one of my favorite blade steels and holds an edge really well>> even better than VG-10.

 

Great read thanks for the link.

I just wipe down my zdp with a tuf cloth every now and then and I've experienced no problems so far :thumbup: