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I Forge Iron

Plated/Coated drive shaft?


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Hello all,

I have done some reading on zinc poisoning and decided to get your opinion. I received an old boat motor from a friend of mine for scrap. While tearing it down to separate aluminum from steel, I came across these two shafts. I thought they would be perfect for some struck tooling, but wasn’t sure about them because of how shiny they are. Should I just scrap them? Should I try to let them rust? I read about the pinholes that iron can bloom through and make it look like the material is all rusted up when it isn’t. Thanks for the advice guys!

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I would doubt that they would be plated with anything in that application.  Shafts are a high friction part and any plating would quickly wear off in use.  If there was any doubt in my mind I would put a bit of something acidic on it, leave it overnight, and see if there was any oxidation the next morning.  Also, you could hit it with a file and see if there is any color difference between the surface and the metal a bit deeper.  Or, if the cut oxidizes differently than the surface. 

"By hammer and hand all arts do stand."

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Oily internal engine/transmission parts can look shiny and resist immediate rusting due to the oils/fluids on them. 

Degrease them to see if they rust. Georges suggestion of removing some to look for differences is good.

Stainless is a possibility but "probably" not typical in internal engine parts unless maybe an outboard motor? 

Also spark test may tell a little of what they are in terms of carbon. 

Stainless wouldnt rust even in the spot ground down while plated would rust in the ground down spot. 

A mix of vinegar, salt and hydrogen peroxide spray will show fairly quickly on degreased steel if it will rust or not. 

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Thanks for the quick replies! I just tested it with a magnet, and it stuck like regular steel. I think that eliminates stainless. I will definitely try cutting it and filing it to see if it rusts! BTW, these are from an old outboard boat motor. 

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  Just for future reference, I copied and pasted this from the internet:

"Stainless steels are iron-based alloys primarily known for their generally excellent corrosion resistance, which is largely due to the steel's chromium concentration. ... Due to this difference, ferritic stainless steels are generally magnetic while austenitic stainless steels usually are not."

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10 hours ago, George N. M. said:

I would put a bit of something acidic on it, leave it overnight, and see if there was any oxidation the next morning.

Or leave it outside for a year or two. Slower, but just as effective.

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