New Magnacut, stained after first use in kitchen

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Arathol said:
You buy a knife to use, expect it to get dirty and discolored no matter what its made of.
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Different steels have different properties, that's a defining factor of knives and a deciding factor when purchasing.

I bought dozens of knives, I certainly did not expect the "super-steel" to get more discolored than the rest of them, instantly.

Arathol said:
the knife is still fully functional.
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A two dollar knife can be functional, literally means nothing.
 
knifeism said:
Magnacut is touted as the most stainless steel in the universe
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By who? I have never seen it marketed that way by Larrin Larrin who made the steel or by any respected maker. In fact, Larrin commented at least once that he was surprised out how resistant to corrosion it turned out to be. Your expectations are not inline with reality.
 
SharpBits said:
By who? I have never seen it marketed that way by Larrin Larrin who made the steel or by any respected maker. In fact, Larrin commented at least once that he was surprised out how resistant to corrosion it turned out to be. Your expectations are not inline with reality.
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Here is Larrin: "The biggest surprise in testing of MagnaCut was how good its corrosion resistance is. It was expected to have corrosion resistance in between S35VN and S45VN, “good” or even “great” but not spectacular. However, the corrosion resistance ended up being even better than 20CV and just under stellar steels like Vanax or LC200N."

And Spyderco uses it in its Salt series.

I use M390 or AEB-L in the kitchen all the time, blades remain clean.

I'm also wondering what's going on .... grinding residue on the surface ? Heat treat dependence ? ....
 
Pure conjecture on my part but Magnacut heat treating makes two or three grades of steel. From the posts, pics, and videos I've seen it looks like if it's run softer in the 60-62 HRC it's very stainless but doesn't hole the edge as well. Run it harder like CRK does at 63-64 HRC and you get some surprising edge holding but that higher hardness have been the only Magnacut I've seen with any issues with staining. This is dismissing the posts that have possible contamination from grinding.
 
Here is Nathan the Machinist Nathan the Machinist on his MC recipe and corrosion resistance: "I give no consideration to corrosion resistance when developing a heat treat. However, the heat treat that I use does maximize the amount of free chromium so it does happen to have the best corrosion resistance of the different heat treat options. Quench rate is important for corrosion resistance because the free chromium is reacting with the carbon in solution on the way down. It is critical to minimize the time in this temperature zone and my quench rate for MC is much faster than industry standard."
 
I have several high carbon kitchen knives, likely 40-60 years old. They are definitely patina-ed, stained from years of commercial use. The staining doesn't affect the food, they sharpen easily. I wouldn't think Magnacut stained that easily, so thanks for the heads up.

I've got enough "supersteel" knives already, and no longer feel the need to buy every new steel that comes out. For pocketknife-type uses, they are all sufficient for my typical uses. For survival situations, I have a credit card!
 
Maximumbob54 said:
Pure conjecture on my part but Magnacut heat treating makes two or three grades of steel. From the posts, pics, and videos I've seen it looks like if it's run softer in the 60-62 HRC it's very stainless but doesn't hole the edge as well. Run it harder like CRK does at 63-64 HRC and you get some surprising edge holding but that higher hardness have been the only Magnacut I've seen with any issues with staining. This is dismissing the posts that have possible contamination from grinding.
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That is not how it works. In fact it can be easier to get high corrosion resistance with high hardness. In terms of heat treatment the biggest effect is whether they use the high or low tempering regime. The 900F+ tempering temperature leads to worse corrosion resistance with stainless steels but is semi-common. The other major effects are how the steel is finished and whether they effectively clean remaining steel particles from the knife. There is a process called passivation where those free particles can be removed with a weak acid.

Edit: This misunderstanding seems to come from the fact that high corrosion resistance steels can have limited hardness from extra chromium in solution to achieve the corrosion resistance. Therefore LC200N and Vanax max out around 60-61 Rc. However, that is when comparing different steel types, not the same steel with a different heat treatment.
 
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Larrin said:
That is not how it works. In fact it can be easier to get high corrosion resistance with high hardness. In terms of heat treatment the biggest effect is whether they use the high or low tempering regime. The 900F+ tempering temperature leads to worse corrosion resistance with stainless steels but is semi-common. The other major effects are how the steel is finished and whether they effectively clean remaining steel particles from the knife. There is a process called passivation where those free particles can be removed with a weak acid.
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or not cross contaminating other steels by using a dedicated clean, fresh belt/tooling)?

*Plus proper tempering

Thanks.
 
Crag the Brewer said:
or not cross contaminating other steels by using a dedicated clean, fresh belt/tooling)?

*Plus proper tempering

Thanks.
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Cross contamination is even worse, yes. Though I have seen a general lack of knowledge that steel particles themselves, even from the same steel, are bad. Then the knife companies vehemently deny the possibility of cross contamination and no one knows that it isn’t the only possibility.
 
Larrin said:
Cross contamination is even worse, yes. Though I have seen a general lack of knowledge that steel particles themselves, even from the same steel, are bad. Then the knife companies vehemently deny the possibility of cross contamination and no one knows that it isn’t the only possibility.
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Same steel even...? :/

I never even thought about (post manufacturing) sharpening....

having separate stones/diamonds/strops.

If one needs to be particular...... I've got more to read, now

-I don't believe that is what is happening on the OP's blade. Probably industry standard treatment type. (just guessing)
 
Steel dust is nothing but surface area.
 
SharpBits said:
By who?
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By everyone: https://gprivate.com/6crr6

SharpBits said:
Larrin Larrin commented at least once that he was surprised out how resistant to corrosion it turned out to be.
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"CPM MagnaCut is a new stainless knife steel designed to be better than anything that has been available before."

Also, and I'm not sure who needs to hear this, but being surprised that something works, is claiming it works.

In terms of staining, it's not better than anything I've ever used, it's worse than everything, to the point I actually need to research stain removers because nothing works.
 
knifeism said:
By everyone: https://gprivate.com/6crr6



"CPM MagnaCut is a new stainless knife steel designed to be better than anything that has been available before."

Also, and I'm not sure who needs to hear this, but being surprised that something works, is claiming it works.

In terms of staining, it's not better than anything I've ever used, it's worse than everything, to the point I actually need to research stain removers because nothing works.
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Take it up with the manufacturer of the knife. They likely messed it up at some stage of production.
 
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