Corrosion Testing of 9 Stainless Knife Steels

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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby The Mastiff » Mon Oct 14, 2019 1:01 pm

Just excellent Larrin! Thank you for putting the time and work into this as usual.

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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby Larrin » Mon Oct 14, 2019 1:03 pm

The Mastiff wrote:
Mon Oct 14, 2019 1:01 pm
Just excellent Larrin! Thank you for putting the time and work into this as usual.
Thanks!
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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby Pelagic » Mon Oct 14, 2019 1:11 pm

zuludelta wrote:
Mon Oct 14, 2019 10:11 am
Pelagic wrote:
Mon Oct 14, 2019 9:54 am
Interesting conclusion for XHP. It's been quite corrosion resistant in my experience.
I think as far as conventional knife usage goes, XHP is "stainless enough" for 95% of the knife community and perhaps to less of an extent, the same can be said for ZDP-189 and CruWear (I carried a Dragonfly in ZDP-189 as my EDC for years & rusting/staining was never a problem with regular common sense maintenance).

That said, I have seen an XHP knife develop a notable layer of surface rust with some staining during constant exposure to seawater over a six-hour period, where a VG10 blade only developed minimal surface rust that was easily wiped away. I suppose in many of these steels, the corrosion resistance rating differences really only become practically apparent in more extreme conditions.
I don't know why, but my cold steel recon 1 and broken skull do very well with my highly corrosive sweat while working on the water and occasional exposure to sea water. Cruwear, in my experience, is an absolute rust bucket compared to XHP.
Last edited by Pelagic on Tue Oct 15, 2019 1:25 am, edited 1 time in total.
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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby Larrin » Mon Oct 14, 2019 1:13 pm

Pelagic wrote:
Mon Oct 14, 2019 1:11 pm
I don't know why, but my cold steel recon 1 and broken skull do very well with my highly corrosive sweat while working on the water and occasional exposure to sea salt. Cruwear, in my experience, is an absolute rust bucket compared to XHP.
Remember that high temperature tempering is common with CruWear which reduces its corrosion resistance.

Edit: And looking at my ratings table again there is a significant difference between the two steels.
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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby Pelagic » Mon Oct 14, 2019 4:45 pm

Larrin wrote:
Mon Oct 14, 2019 1:13 pm
Pelagic wrote:
Mon Oct 14, 2019 1:11 pm
I don't know why, but my cold steel recon 1 and broken skull do very well with my highly corrosive sweat while working on the water and occasional exposure to sea salt. Cruwear, in my experience, is an absolute rust bucket compared to XHP.
Remember that high temperature tempering is common with CruWear which reduces its corrosion resistance.

Edit: And looking at my ratings table again there is a significant difference between the two steels.
I know heat treat has a lot to do with corrosion resistance. I have no long term experience with any XHP aside from that of cold steel (one particular heat treat). But I subject my knives to a highly corrosive environment and i can say they do quite well. Absolutely better than spyderco's s30v. More similar to s110v really (but not quite as good as s110v).
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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby Bloke » Mon Oct 14, 2019 5:01 pm

Thanks yet again for an informative read Larrin. :)
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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby yoteslayer » Mon Oct 14, 2019 5:22 pm

Nice job. Very good info. Thanks!

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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby Vivi » Mon Oct 14, 2019 5:24 pm

Really cool stuff, thank you for sharing. This is a lot more interesting to me than how many feet of cardboard X steel cuts. There's never a time I need to cut 5,000 boxes in a single go but there's countless days during the year where my knife sits in a sweaty pocket all shift.

Surprised at how bad XHP did. I've never used it but people always reported it being pretty corrosion resistant.

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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby JacksonKnives » Mon Oct 14, 2019 9:49 pm

The Meat man wrote:
Mon Oct 14, 2019 9:14 am
Here's what it looked like.

[images on page 1]

I could not clean it off. It gradually wore off after a few weeks of use.
Very interesting. There was a highly-publicized case a few years back of a China-made s35vn blade with a similar patina in nearly identical conditions (cutting meat) that many armchair experts assumed must have been "fake" steel. I think eventually they got that one tested to prove it was real. A surface finish like this (I'm assuming belt finished and then buffed?) seems to facilitate strange interactions with meat juice.

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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby Larrin » Tue Oct 15, 2019 5:39 am

Just goes to show the importance of doing experiments on separate specimens made the same way rather than relying on anecdotes with knives of different heat treatments and finishes. Such anecdotes may sometimes be useful when it comes to comparing knives, but may not be reliable in terms of understanding how steels compare.
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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby Pelagic » Tue Oct 15, 2019 8:22 am

Larrin, what if XHP contained 2% vanadium? Would it likely be much more corrosion resistant? Since vanadium forms carbides more readily, would this result in fewer chromium carbides and this more free chromium in the matrix?

I feel 16% is a lot of chromium, however with 1.6% carbon and no other carbide formers, the amount of free chromium takes a big hit.
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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby The Meat man » Tue Oct 15, 2019 8:38 am

JacksonKnives wrote:
Mon Oct 14, 2019 9:49 pm
The Meat man wrote:
Mon Oct 14, 2019 9:14 am
Here's what it looked like.

[images on page 1]

I could not clean it off. It gradually wore off after a few weeks of use.
Very interesting. There was a highly-publicized case a few years back of a China-made s35vn blade with a similar patina in nearly identical conditions (cutting meat) that many armchair experts assumed must have been "fake" steel. I think eventually they got that one tested to prove it was real. A surface finish like this (I'm assuming belt finished and then buffed?) seems to facilitate strange interactions with meat juice.
Yeah it seems that under certain conditions, meat juice will react with even "stainless" steel. I recall fellow member TkoK83Spy experiencing similar discoloration on M390, from the same cause.
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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby Ankerson » Tue Oct 15, 2019 8:42 am

The Meat man wrote:
Tue Oct 15, 2019 8:38 am
JacksonKnives wrote:
Mon Oct 14, 2019 9:49 pm
The Meat man wrote:
Mon Oct 14, 2019 9:14 am
Here's what it looked like.

[images on page 1]

I could not clean it off. It gradually wore off after a few weeks of use.
Very interesting. There was a highly-publicized case a few years back of a China-made s35vn blade with a similar patina in nearly identical conditions (cutting meat) that many armchair experts assumed must have been "fake" steel. I think eventually they got that one tested to prove it was real. A surface finish like this (I'm assuming belt finished and then buffed?) seems to facilitate strange interactions with meat juice.
Yeah it seems that under certain conditions, meat juice will react with even "stainless" steel. I recall fellow member TkoK83Spy experiencing similar discoloration on M390, from the same cause.

In the end we have to remember it's stain----less..... Not stainless...

All steels will and can rust, stain etc, with the only real exception being H1 and that's not steel per say.

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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby JD Spydo » Tue Oct 15, 2019 9:07 am

Another super thread Larrin :) Now this brings up a subject I've been meaning to talk to you about for some time now. There was a machine tool shop I worked at some time back where we did all kinds of testing. We had every type of hardness tester along with toughness testing equipment. But we had a chemical compound that some of the guys that worked there did corrosion testing with. The chemical compound was called "Aqua Regia" and they used it solely for testing corrosion on metals and coatings.

I'm just wondering if that "Aqua Regia" played a role in your testing?

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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby JD Spydo » Tue Oct 15, 2019 9:12 am

The Meat man wrote:
Mon Oct 14, 2019 8:39 am
Excellent article Larrin. Very interesting to see CTS BD1N way up there. I've not had any rust with it, but I have had it patina after cutting some pork chops.
Thanks as always for your contributions!
That's interesting Meat Man because over the years I've found that food acids and fats and other compounds from meat, poultry and fish all seem to have their own strange effects on various blade steels and other metals.

ZDP-189 being one of the very worst I've encountered as of yet.

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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby Larrin » Tue Oct 15, 2019 9:28 am

JD Spydo wrote:
Tue Oct 15, 2019 9:07 am
Another super thread Larrin :) Now this brings up a subject I've been meaning to talk to you about for some time now. There was a machine tool shop I worked at some time back where we did all kinds of testing. We had every type of hardness tester along with toughness testing equipment. But we had a chemical compound that some of the guys that worked there did corrosion testing with. The chemical compound was called "Aqua Regia" and they used it solely for testing corrosion on metals and coatings.

I'm just wondering if that "Aqua Regia" played a role in your testing?
Aqua regia is one of the acids that Crucible has used in their corrosion testing. I used their data including the aqua regia tests in my previous corrosion article. In my testing I did not use it.
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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby Larrin » Tue Oct 15, 2019 10:39 am

Ankerson wrote:
Tue Oct 15, 2019 8:42 am
All steels will and can rust, stain etc, with the only real exception being H1 and that's not steel per say.
Why isn't H1 steel?
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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby JonLeBlanc » Tue Oct 15, 2019 10:51 am

Really interesting article, and one that has a definite bearing on practical concerns!
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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby Ankerson » Tue Oct 15, 2019 11:27 am

Larrin wrote:
Tue Oct 15, 2019 10:39 am
Ankerson wrote:
Tue Oct 15, 2019 8:42 am
All steels will and can rust, stain etc, with the only real exception being H1 and that's not steel per say.
Why isn't H1 steel?

It's an alloy, we all had this discussion a very long time ago, like 15 years ago or so.

That's why I said per say...

I don't remember all of it, Sal can likely ring in with more info I think.

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Re: Corrosion Testing of 9 Stainless Knife Steels

Postby Larrin » Tue Oct 15, 2019 11:39 am

Ankerson wrote:
Tue Oct 15, 2019 11:27 am
It's an alloy, we all had this discussion a very long time ago, like 15 years ago or so.

That's why I said per say...

I don't remember all of it, Sal can likely ring in with more info I think.
Most any steel can be called an "alloy steel." H1 is a steel.
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