help identifying aluminum alloy

[blockmanjohn]

I bought this piece of 1/2" aluminum plate on eBay. It has this pattern on one side, and the other side seems to be just a mill finish. Does anyone know what this pattern means? Thanks, John.

 

[mayhugh1]

View attachment 114257 I bought this piece of 1/2" aluminum plate on eBay. It has this pattern on one side, and the other side seems to be just a mill finish. Does anyone know what this pattern means? Thanks, John.

Are you sure it's not a peel-off protective piece of plastic? - Terry

 

[blockmanjohn]

It is not a peel-off piece of plastic. The pattern also has a very noticeable texture to it.

 

[doc1955]

To me it looks as if someone pealed off the protective coating then put it back down and left it to corrode.

 

[chrsbrbnk]

thats how it looks if you leave the plastic cover on to long like a decade or two the aluminium gets stained like that get the sticky off with a solvent then buff with a random orbit and some scotch brite

 

[blockmanjohn]

Upon further scrutiny I think that is exactly what happened. Thanks for the replys, John.

 

[chrsbrbnk]

were you able to identify the alloy? some aluminium alloys machine poorly

 

[blockmanjohn]

It machined very well, but I have no idea how to identify the particular alloy.

 

[Deholby]

first guest is K1oo Cast tooling plate.
Its one of the plates that alway have a plastic sheet on it to protect the finish.

Is the chip a dull looking when cutting? Its also a little on the gummy side cutting too.

If its Cast plate, is soft and tension is only about 3200 psi, where 6061 t6 is 45000 psi