Carbon steel can make stainless rust?

[mrdavidross321]

i just read on a very old post someone said that Carbon steel can cause some Stainless steels to rust? i have never heard this before but then again i am somewhat new to the knife world.

does anyone know any truth to this?

 

[me2]

Absolutely true. If stainless is contaminated with carbon steel, such as in using a grinding wheel on first carbon then stainless, the stainless will rust. If a knife blade is contaminated with steel dust during production, the stainless can definately rust. When welding high purity piping for medical or semi-conductor applications, great care is taken to avoid cross contamination. I've seen welds cut out and redone because the prep work was done with a bandsaw that was first used to cut carbon steel threaded rod.

 

[knarfeng]

i just read on a very old post someone said that Carbon steel can cause some Stainless steels to rust? i have never heard this before but then again i am somewhat new to the knife world.

does anyone know any truth to this?

Truth. And not limited to the knife world. That is why stainless steel is quite often passivated (dipped in an acid solution) after forming operations in manufacturing. We do it all the time in our shops where I work.

"Stainless" steel (most metallurgists of my acquaintance prefer the term "Corrosion REsistant Steel", or CRES) does not rust because it forms an adherent oxide layer on the outside. That oxide layer forms a barrier against oxygen and water, both of which are necessary for the oxidation reaction that we call "rust".

Impurities such as steel particles from non-stainless steel can cause a break in that oxide layer, allowing the passage of oxygen and moisture, allowing the stainless steel to rust.

 

[bomber_man_jj]

Rusting steel will also oxidize aluminum that its in contact with. At my last job we had to fix up a few combo(aluminum top,steel frame) semi trailers and we played hell cleaning where the aluminum support braces bolted to the steel. Though knife grade materials might differ.

 

[Robert Ptacel]

I've never really thought about this before so does this mean everybody uses different sharpening tools to sharpen stainless and carbon steels?

 

[Jason B.]

I've never really thought about this before so does this mean everybody uses different sharpening tools to sharpen stainless and carbon steels?

I never thought much about it but I've always cleaned my stones before switching to different knives or steels. When it comes to the actual sharpening part I do use different tools depending on if its stainless or not.

 

[Obsessed with Edges]

I've never really thought about this before so does this mean everybody uses different sharpening tools to sharpen stainless and carbon steels?

Many people find that different sharpening tools work better for different types of steel. Some steels respond more favorably to certain types of sharpening tools. As it applies to knife sharpening, for the vast majority, I doubt the question of cross-contamination between stainless/non-stainless is of major concern. 99% of rust issues can be avoided simply by keeping the knives & tools clean and dry. Treat every blade & tool as if it wasn't stainless, and you won't have any issues. Bear in mind, ANY steel will rust, given the right conditions. Even so-called 'stainless' is just a little more 'rust resistant' than so-called 'non-stainless'. It's not rust-proof.

In order for rust to form on any steel, stainless or not, you need (at a minimum) iron and oxygen, in the presence of moisture. Keep the moisture under control, and the rest is pretty much moot. Other things, like salt & acids, can accelerate rusting. Keep everything clean, and that's not much of an issue either.

If cross-contamination was a major issue with knives & sharpening, we'd probably have warning labels on every sharpening tool, cautioning against using on both stainless & non-stainless. There's really not much need to worry about it here.

 

[Robert Ptacel]

Many people find that different sharpening tools work better for different types of steel. Some steels respond more favorably to certain types of sharpening tools. As it applies to knife sharpening, for the vast majority, I doubt the question of cross-contamination between stainless/non-stainless is of major concern. 99% of rust issues can be avoided simply by keeping the knives & tools clean and dry. Treat every blade & tool as if it wasn't stainless, and you won't have any issues. Bear in mind, ANY steel will rust, given the right conditions. Even so-called 'stainless' is just a little more 'rust resistant' than so-called 'non-stainless'. It's not rust-proof.

In order for rust to form on any steel, stainless or not, you need (at a minimum) iron and oxygen, in the presence of moisture. Keep the moisture under control, and the rest is pretty much moot. Other things, like salt & acids, can accelerate rusting. Keep everything clean, and that's not much of an issue either.

If cross-contamination was a major issue with knives & sharpening, we'd probably have warning labels on every sharpening tool, cautioning against using on both stainless & non-stainless. There's really not much need to worry about it here.

Thank you for the info.

 

[mrdavidross321]

wow, i had no idea! i love the world on knowledge on this forum:thumbup: