Heat treat and corrosion

Yes, stainless and high alloy steels. Chromium carbides dissolve during austenitizing putting chromium and carbon into solution making it stain resistant.

There’s not much change in stain resistance in carbon and low alloy steels during heat treating.

Hoss

Edit: carbon in solution does nothing for stain resistance, only hardness.
 
I have s35vn
S45VN
Magnacut
D2CPM
440C
And AEB-L

ordered from Alpha knife supply. Should I aneal them before testing? I live near the bay and was planing on getting a bucket of bay water, spraying them once a week while leaving them outside. They will be held down to an untreated 2/6 and left in the central Florida elements to see how they hold up. I also ordered 1095 as a control. They will either be wire tied or held with a double stick tape so there should be no galvanic reaction between dissimilar medals.
 
Tjstampa said:
I have s35vn
S45VN
Magnacut
D2CPM
440C
And AEB-L

ordered from Alpha knife supply. Should I aneal them before testing? I live near the bay and was planing on getting a bucket of bay water, spraying them once a week while leaving them outside. They will be held down to an untreated 2/6 and left in the central Florida elements to see how they hold up. I also ordered 1095 as a control.
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Non heat treat stainless behaves differently than treated....
Couldn't tell by reading How you were going to start?


Idk if Scott first posted this Here or BCUSA, I couldn't find a different link?

Good for ref, and discussion. https://bushcraftusa.com/forum/threads/knife-steel-corrossion-experiment.301809/
 
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It’s hard for me to understand what exactly you are trying to do.

The MagnaCut data sheet has some information on there that will help.

Hoss
 
Tjstampa said:
I have s35vn
S45VN
Magnacut
D2CPM
440C
And AEB-L

ordered from Alpha knife supply. Should I aneal them before testing? I live near the bay and was planing on getting a bucket of bay water, spraying them once a week while leaving them outside. They will be held down to an untreated 2/6 and left in the central Florida elements to see how they hold up. I also ordered 1095 as a control. They will either be wire tied or held with a double stick tape so there should be no galvanic reaction between dissimilar medals.
Click to expand...

Part of me really wants to tell you to certainly anneal them before testing but the other part of me thinks that’s a mean thing to do.

There are plenty of tests and data out there on this topic already. The tests seem sound and the results line up with what’s expected. I’m not sure how your test would differ or what sort of new insight you might gain.
 
It would help us to know what problem you are trying to solve.
If you are making hooks or pot hangers for your patio, there might be some reason for this.
If you are making a knife, even a diving knife, there is not much point in it. You will not get the kind of exposure that the tests get. Most of the steels you list have been tested and their corrosion resistance is stated in their data sheets.

About the only use of a knife that the test would apply to is a knife on a boat or fishing pier that satays out in the elements to clean fish 24/7. Those type knives are usually considered consumables and are replaced due to repeated sharpening more than corrosion.

There have been several tests run on this subject. Use the custom search engine in the stickys to search, "Corrosion Testing". Here are just two of them:

Corrosion testing

So after getting a couple of the top contenders (as a benchmark) from this testing, I decided to do my own testing in a variety of conditions and ways. This will be ongoing testing over the coming months/years. I'm using some sample blades in 1095 steel that were sandblasted and degreased for...
www.bladeforums.com www.bladeforums.com

Comment on knives and corrosion:
Corrosion resistance has nothing to do with hardness. It is about the availability of the corrosion resistant elements in the matrix of the steel - Mainly chromium - to keep water and oxygen from reacting with then iron in the blade. Proper HT temps will increase the free chromium in the final blade.
Corrosion resistance is most effective if provided by a shielding substance. Waxes, oils, and such are applied to the blade will prevent corrosion the most effective way.
Proper care cleaning, and storage are the best ways to avoid corrosion. Wash dirty knives, dry all knives when done for the day (even if they only sat on a table at a show), and oil/wax/lube them before storage. NEVER store a knife in the sheath long term. The chemicals and moisture in the sheath can damage the blade.
The patina on a carbon steel blade is a form of corrosion resistance. It is nothing like stainless steel but helps prevent rust to some degree. This is why etching blades to get a dark patinaed surface is common.
 
I have family and several friends that run fishing charters and are wanting real world testing for knife steel that at times their life may depend on such as cutting an ancher rope that won't release or line caught around a clients hand or leg with a large fish. They all want good knives but they don't always have ti.e to wash and oil them ergo they came to me with this idea and chipped in some money for me to buy the knife steel. I am hoping to get some H1 and H2 to add to this. One claims his spyderco salt has rusted.
 
Tjstampa said:
I have family and several friends that run fishing charters and are wanting real world testing for knife steel that at times their life may depend on such as cutting an ancher rope that won't release or line caught around a clients hand or leg with a large fish. They all want good knives but they don't always have ti.e to wash and oil them ergo they came to me with this idea and chipped in some money for me to buy the knife steel. I am hoping to get some H1 and H2 to add to this. One claims his spyderco salt has rusted.
Click to expand...
Any steel will rust if not cared for but other things like surface finish, hardness, low temper heat treat or high temper heat treat.

A lot of these tests have been done already and a little googling should show you corrosion tests done by others.

I would opt for magnacut. I wouldn’t even bother testing CPM D2 since it’s not even classified as a stainless.
 
I suspected this was for fishing. Just rinsing off as you finish cleaning the fish will go a long way towards preventing surface corrosion.
A fillet knife or other boat knife will likely be sharpened all the time, so the edge is always going to be corrosion free. If it is dull, it won't matter how good the surface is when cutting a rope or fouled line off someone.
Real world survival is all about edge and HT, not the surface. A good HT is the most important thing.
I would have to look at the test charts, but I also think magnacut would be a good choice.
 
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Maybe I am missing something here, which is entirely possible, but you say you have those 6 steels from Alpha Knife Supply and you are going to do corrosion testing on them?

They must be heat treated first, not annealed. They come annealed. You have to harden/temper them before they become stainless. If you do testing as is (they come annealed), they will all rust.
 
Yes, Stainless steel in annealed state, most of chromium are tied up with carbon in Cr carbide form. All of these chromium provide zero corrosion resistance that why annealed stainless rust very easily.

Once you heat treated it, some of the chromium carbide with dissolved and became free chromium which provide corrosion resistance.

Higher austenitizing temp = more Cr dissolved = higher corrosion resistance.
The higher tempering temp = more free Cr got tied up the the carbon = lower corrosion resistance

Steel like M390 still can still be hardened at much lower than the recommended austenitizing temp like 1900F but the corrosion will be much lower than it should be.
 
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