What brass can be copper plated and used as a boat rudder? 1

[emery4]

I found this boat rudder that is very heavy, copper plated, bright yellow brass, has no taste, yellow filings, no magnetic attraction at all, resonates with a dull thud,the shaft also appeaers to made of the same metal.Can you help me identify this metal?

 

[Ron]

Could be a silicon bronze or "yellow brass". Both are used for marine accessories, though "yellow brass" is more likely for older items. Either can be copper plated. Copper plates to many metals and very easily plates to bronzes and brasses since both are copper alloys.

 

[EdStainless]

This may not be copper plated, but actually dealloyed. When the Sn or Zn (depending on alloy) dissolved some of the Cu dissolves also and redeposits back onto the surface. The surface will have a bright Cu look and be pure Cu. Most lower alloy brass and bronze will do this in seawater, or even aggressive fresh water.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube