Why would a stainlees steel prop show rust?

[Salty Sal]

Thought stainless steel doesn't rust.<br />Noticed my prop has a slight rusty have in<br />various areas. How do I remedy this problem?<br />Thanks for your reply.

 

[Joe Reeves]

Re: Why would a stainlees steel prop show rust?

Sal..... What you're seeing is simply surface rust, nothing to be concerned about. Many stainless steel items in the marine line are a mixture of various metals, stainless steel being the major portion of the item. Due to this mixture, surface rust will appear.<br /><br />If the prop was strictly stainless and no other metals were present, it would be quite brittle which would lead to a complete failure of the blades in a very short time.<br /><br />Gotta take the good with the bad sometimes.

 

[seahorse5]

Re: Why would a stainlees steel prop show rust?

That's why it is called STAINLESS steel, not STAINPROOF steel!

 

[vidar]

Re: Why would a stainlees steel prop show rust?

Hi! the prop is a casting called cf8...iits a 304 steel....if it was a cf8m ..316 steel. it woud not rust as easy but you coud have more chance of corroson on engine becouse of its higher galvanic potensial...its a trade off...

 

[Solittle]

Re: Why would a stainlees steel prop show rust?

Sal - Take a plastic scrub pad & some Comet to clean the crud & rust - Then use and auto or marine polish/wax. Mine do the same.

 

[Salty Sal]

Re: Why would a stainlees steel prop show rust?

Thanks everyone!

 

[Salty Sal]

Re: Why would a stainlees steel prop show rust?

Thanks everyone!

 

[AUGIDAWG]

Re: Why would a stainlees steel prop show rust?

Is your prop an OMC factory prop?<br /><br />If it is, that would explain the rust.<br />They are made in Mexico from inferior material.

 

[walleyehed]

Re: Why would a stainlees steel prop show rust?

I gotta step in here, not all OMC props fall into that group. The Nauticpro series is the only one OMC has had any problem with in SS. <br />The metalurgy is not inferior, it is actually better than that required to be finished as a polished prop. The props I speak of were intended to be painted, or teflon coated, and yes, cheaper because of the lack of work required to polish it. I run a nauticpro, and have hit rocks, trees, even a gill net at WFO, and it never shows any signs of being inferior. I've torn the snot out of my share of alum. props, and dinged a few SS props.....OMC props are not the inferior ones....<br />Run a Ballistic up against a tiny little rock and see what happens to it...........

 

[M13]

Re: Why would a stainlees steel prop show rust?

"Stainless steel is essentially a low carbon steel which contains chromium at 10% or more by weight. It is this addition of chromium that gives the steel its unique stainless, corrosion resisting properties.<br /><br />The chromium content of the steel allows the formation of a rough, adherent, invisible, corrosion-resisting chromium oxide film on the steel surface. If damaged mechanically or chemically, this film is self-healing, providing that oxygen, even in very small amounts, is present. The corrosion resistance and other useful properties of the steel are enhanced by increased chromium content and the addition of other elements <br /><br />Stainless does not “rust” as you think of regular steel rusting with a red oxide on the surface that flakes off. If you see red rust it is probably due to some iron particles that have contaminated the surface of the stainless steel and it is these iron particles that are rusting. Look of the source of the rusting and see if you can remove it from the surface. <br />If the iron is embedded in the surface you can try a solution of 10% nitric and 2% hydrofluoric acid at room temperature or slightly heated. Wash area well with lots and lots of water after use. Commercially available “pickling paste” can also be used."

 

[AUGIDAWG]

Re: Why would a stainlees steel prop show rust?

Iron particles on the surface of stainless can be removed by a process called "passivation".<br />Then the chromium oxide forms and the surface will stay rust free.<br />It would be cheap for the manufacturer to send a batch out for this process. But, would be inconvienient for an idividual to have it done.<br />If you are using the prop in salt water, you may encounter chloride stress corrosion, which may cause catostraphic failure if inferior materials are used, like from Mexico.