MagnaCut Corrosion Resistance testing thread

[ladybug93]

Hi David,

Yes, I had a Native Salt early on, tested it and was pleased with the results. I also have a Sage 5 with MC and the MC Mule. The future will be interesting. I also carry a serrated Pacific quite a bit.

sal

[bjz]

Wait, sage 5 in MC?

I'd be not too sure that this will happen.

Seems like the Sage 5 LW gets to be "just" an intern testing platform sometimes, but not necessarily with regular production in mind...

I could of course be wrong though in this case!

One can hope…I’ve really been wanting to try a sage 5 lw but at current price points s30v and M4 haven’t been compelling enough to prioritize another purchase in that range right now…MC sage would undoubted be a must have for me before N5 or manix in MC. Heck, the perfect MC model for me would be SE tenacious LW (that is asking a lot though).

[Wartstein]

Wait, sage 5 in MC?

I'd be not too sure that this will happen.

Seems like the Sage 5 LW gets to be "just" an intern testing platform sometimes, but not necessarily with regular production in mind...

I could of course be wrong though in this case!

One can hope…I’ve really been wanting to try a sage 5 lw but at current price points s30v and M4 haven’t been compelling enough to prioritize another purchase in that range right now…MC sage would undoubted be a must have for me before N5 or manix in MC. Heck, the perfect MC model for me would be SE tenacious LW (that is asking a lot though).

Second time I totally forgot something obvious today , and that is the actual existence of the M4 Sage 5... sure makes a MC Sage more likely, and would be another step away from the Para 3 as the small comp.lpck model that always gets all the steels and variants.

[Xplorer]

I was speaking with my friend Chad Kelly today about these results and he hinted to me that the results in this test might not technically be “galvanic corrosion”. My understanding of the chemical process of galvanic corrosion is kindergarten level at best so hopefully Chad will come join the conversation with his observations. Or maybe Larrin if he reads this?

Though I’m uncertain about the chemical process of actual galvanic corrosion, I still did this test for a specific reason. Any time I have been able to make a Salt knife show any type of corrosion, the corrosion started with the hardware. The rust from the hardware would bleed onto the steel and if it stayed there long enough it would start to corrode the knife steel in a way that even unlimited exposure to salt water would not. I have experienced this phenomenon equally with lc200n, Magnacut and Vanax, all of them to a similar level, and the results were easily replicated in this short test. The only steel that seems to be more or less pervious to even this type of corrosion is H1.

So, it is a worthwhile question IMO to consider what is actually causing this chemical process, because it is the reason for almost any rust scenario that might occur in a salt knife. Chad is way ahead of me on this stuff so hopefully he will chime in. If this is not “galvanic corrosion” then it would be interesting to understand why the corrosion and rust of one steel is so corrosive to another steel that is otherwise “corrosion proof”. Thanks in advance to anyone who can step in with some knowledge.

OK, to clarify..I do believe we're seeing some galvanic corrosion in your tests but there's some specifics that should be taken into consideration that are important in understanding both what were seeing and what we would want to know.

First, the main take-away from your test is clear. LC200N and MagnaCut are fairing about the same as one another in this experiment. Given what we all already know about LC200N corrosion resistance, this is a really good result for Magnacut.

Galvanic corrosion is a process of corrosion by way of electrolysis that occurs when two dissimilar metals are bathed in an electrolyte solution. In this process one metal becomes a sacrificial anode and corrodes faster than normal and the other becomes a protected cathode and corrodes slower than normal. The differences between metals are known and we can reliably calculate the galvanic corrosion potential between metals mathematically. The range of differences between metals means that electro-chemical contact with one given metal can make your blade an anode, while contact with another metal can make your blade a cathode, and another could have no G.C. reaction whatsoever. So, when testing for G.C. the "other metal" is really important.

I'm unsure what the nail is made from exactly, but based on the degree of corrosion on the nail it doesn't appear to be the protected cathode in this duo. It appears that if G.C. is the main factor the nail would clearly have to be the sacrificial anode. In that case the blade would be additionally protected as the cathode and the blade corrosion would be even less likely. It is possible that the nail is still the cathode and also so lacking in rust resistance that it's blooming despite being the protected cathode and therefor causing the blade the corrode, but not knowing the make-up of the nail makes it unclear. Either way, while the tests so far may show us how the two knife steels compare with each other it isn't necessarily showing us the result we should expect from knife hardware. The degree with which the accelerated rust formation from the nail is causing other corrosive effects is a separate factor that I don't know as much about.

If you do this test with some of the hardware from a Salt knife (or other Spyderco hardware if you want) we would see not only the differences between the steels (which I expect will be no difference) but we will also get a better look at the degree and severity to which galvanic corrosion is likely to occur in a Magnacut knife. The results are likely to be very different from what we've seen so far. For example, if the hardware was made from Magnacut there would be zero G.C. reaction. The similarity between Magnacut and the hardware that Spyderco uses for a Salt knife (from a metal G.C. reaction perspective) is likely to be very close and the potential for G.C. should be close to zero if not completely zero.

Anyway...that's all I wanted to say. Thanks for listening.

[sal]

Warstein is correct. When we're working with new material, we like to test the material and also let the maker/partner learn how to work it. It's been a MagnCut test piece that I've been using quite a bit. Very nice all around blade steel. Thanx Larrin, Crucible, Niagara and Larrin's Dad.

What models we'll make in MC is yet to be determined. I'm sure Eric has a large order in for steel, or he never would have gambled on the Native 5 Salt. We need to know demand from you and everyone involved in our "business-chain".

To be honest, I'm a steel Junky and I enjoy most any blade steel just appreciating it's "forte" and it's "work" (eg; K390 in humid area).

sal

[sal]

Good stuff Chad.

Email going out tomorrow.

sal

[Wartstein]

Warstein is correct. When we're working with new material, we like to test the material and also let the maker/partner learn how to work it. It's been a MagnCut test piece that I've been using quite a bit. ....
...

Thanks for the confirmation and insight, Sal!

In any case it would be nice to actually see an MC Sage 5 LW some day.

[Soanso McMasters]

Warstein is correct. When we're working with new material, we like to test the material and also let the maker/partner learn how to work it. It's been a MagnCut test piece that I've been using quite a bit. Very nice all around blade steel. Thanx Larrin, Crucible, Niagara and Larrin's Dad.

What models we'll make in MC is yet to be determined. I'm sure Eric has a large order in for steel, or he never would have gambled on the Native 5 Salt. We need to know demand from you and everyone involved in our "business-chain".

To be honest, I'm a steel Junky and I enjoy most any blade steel just appreciating it's "forte" and it's "work" (eg; K390 in humid area).

sal

There’s so much (well deserved) hype around Magnacut that I don’t think you can go wrong with Magnacut models, perhaps with the exception of something incredibly obscure. Most folks I have talked to can’t wait to try this steel.

[Evil D]

For example, if the hardware was made from Magnacut there would be zero G.C. reaction. The similarity between Magnacut and the hardware that Spyderco uses for a Salt knife (from a metal G.C. reaction perspective) is likely to be very close and the potential for G.C. should be close to zero if not completely zero.

I was under the impression that all of the liners and hardware on the Caribbean were all made from LC200N as well for this reason, but it ended up still having the same issues so either they didn't use LC for all that hardware after all or it didn't prevent it since they had to change to coated hardware.

[Woodpuppy]

Does heat treat play a part in differential corrosion between hard blade and softer liners etc. of the same alloy?

[Surfingringo]

For example, if the hardware was made from Magnacut there would be zero G.C. reaction. The similarity between Magnacut and the hardware that Spyderco uses for a Salt knife (from a metal G.C. reaction perspective) is likely to be very close and the potential for G.C. should be close to zero if not completely zero.

I was under the impression that all of the liners and hardware on the Caribbean were all made from LC200N as well for this reason, but it ended up still having the same issues so either they didn't use LC for all that hardware after all or it didn't prevent it since they had to change to coated hardware.

I believe the liners are lc200n but the hardware is not.

[Brock O Lee]

That is an impressive test result!

I'm still hoping for a MC Military, but I would most likely buy any of the large (>3.5 inch) models if they were offered in MC.

[Eli Chaps]

Warstein is correct. When we're working with new material, we like to test the material and also let the maker/partner learn how to work it. It's been a MagnCut test piece that I've been using quite a bit. Very nice all around blade steel. Thanx Larrin, Crucible, Niagara and Larrin's Dad.

What models we'll make in MC is yet to be determined. I'm sure Eric has a large order in for steel, or he never would have gambled on the Native 5 Salt. We need to know demand from you and everyone involved in our "business-chain".

To be honest, I'm a steel Junky and I enjoy most any blade steel just appreciating it's "forte" and it's "work" (eg; K390 in humid area).

sal

I agree with David in that I think, at least for the foreseeable future, MagneCut is going to sell quite well no matter the platform.

I'd love to see it in the Seki models but if it has to be Golden then I'm quite interested in a M2LW.

[JSumm]

I agree with David in that I think, at least for the foreseeable future, MagneCut is going to sell quite well no matter the platform.

I'd love to see it in the Seki models but if it has to be Golden then I'm quite interested in a M2LW.

I agree with all of this. Instant buy for me. Well, assuming I just didn't buy something else.

[James Y]

Is it possible to make not only the liners, but also the screws, stop pins/spacers, etc., out of Magnacut, or would that drive the cost up exponentially? Is it possible to even make screws out of the same steel as the blade? If it could be done, and without much of a cost increase, I would imagine that that would be better and longer-lasting for all-around corrosion resistance than coating the hardware.

Then again, I know nothing about manufacturing.

Jim

[Xplorer]

For example, if the hardware was made from Magnacut there would be zero G.C. reaction. The similarity between Magnacut and the hardware that Spyderco uses for a Salt knife (from a metal G.C. reaction perspective) is likely to be very close and the potential for G.C. should be close to zero if not completely zero.

I was under the impression that all of the liners and hardware on the Caribbean were all made from LC200N as well for this reason, but it ended up still having the same issues so either they didn't use LC for all that hardware after all or it didn't prevent it since they had to change to coated hardware.

This speaks to what I am seeing in Lance's results here as well. There is definitely more going on here than just galvanic corrosion. For that matter it appears that there may be more natural rust occurring here than G.C.. If the hardware on an LC200N bladed knife is made from LC200N the corrosion between the parts is not G.C. because the potential for electrons to move and material to be removed through electrolysis isn't there. If there is no dissimilarity neither metal will take on the role of anode or cathode.

Keep in mind that galvanic corrosion usually occurs under water and often doesn't result in visible rust. The G.C. process pulls material out of the anode and causes pitting. The actual red rust is happening through oxidation which is an oxygen exposure process akin to burning. The amount of material that is available to oxidize may be increased by G.C. but when we see a lot of rust happening quickly and without any pitting (like Lance's experiment initially showed) we cannot attribute all of that red oxidation to G.C. by-product.

In a past carrier I spent years doing demonstrations and training people on a variety of chemistry issues, and G.C. was one of them. From that experience I have come to understand that process extremely well. But, I am not a rust expert by any means. I am hopeful that someone with more knowledge than I have on the subject of rust can offer some additional insight as to what else we are seeing. There is no doubt that the results you've experienced and those Lance and others have experienced are real and have a cause. But, when the components that corrode are the same material as one another G.C. just isn't the answer.

[JRinFL]

Is it possible to make not only the liners, but also the screws, stop pins/spacers, etc., out of Magnacut, or would that drive the cost up exponentially? Is it possible to even make screws out of the same steel as the blade? If it could be done, and without much of a cost increase, I would imagine that that would be better and longer-lasting for all-around corrosion resistance than coating the hardware.

Then again, I know nothing about manufacturing.

Jim

Yes and YES! Cost would go way up as it would all need to be custom made out of a relatively expensive steel. There are other stainless steels that will work for hardware. Coating is likely more cost effective.

[Xplorer]

I should add that when considering galvanic corrosion potential you don't necessarily have to have 2 identical stainless steels to stop G.C. from occurring. This is getting into a deeper level of specificity that is probably necessary but it might be helpful for better overall understanding of the subject here.

The potential for G.C. between any 2 austenitic stainless steels, or any two martensitic stainless steels can be as low as zero even if they're not the exact same steel. The movement of ions or electrons occurs when one metal is more noble than the other. A more noble steel is more corrosion resistant and is therefor more stingy about giving up it's ions (In general gold is the most noble, next is silver, next is titanium, next is stainless steel). A less noble steel (or any metal) gives up it's ions more easily (zinc is a good example of the least noble of metals). The further two metal are from each other in terms of nobility the more current the two will create through G.C. if the rest of the necessary elements are in place. Two stainless steels can have differences in their composition and still have the same nobility which effectively stops the potential for a G.C. reaction.

Environmental factors can have a big impact on the potential for G.C.. Areas on a coast line with high surf will produce the greatest reaction because of the increased availability of salt water in the air (which is why Lance's home is such an exceptional testing ground). Due to environmental impacts, two steels that are close in nobility that show zero signs of G.C. over a lifetime in dry conditions could still have a small reaction in salty, high-humidity conditions.

Surface area also plays a role. If the surface area of the cathode metal is large and the surface area of the anode is small the cathode won't receive as much protection as it would if the anode had more surface area.

So, while I agree that coated parts (with the right coating) could indeed provide an effective barrier to electrochemical contact and eliminate the potential for G.C., coating isn't a necessary solution if the cost of coating is greater than the cost of making the parts from a steel with the same or very similar nobility.

[standy99]

So do we ever get into the need for Sacrificial Anodes on knives

https://www.boatus.com/expert-advice/ex ... nodes-work

[VashHash]

So do we ever get into the need for Sacrificial Anodes on knives

https://www.boatus.com/expert-advice/ex ... nodes-work

The true purpose of the spyder hole is for attaching anodes. Why did it take us so long to figure this out?