Question on Hard Brass 2

[franck]

Hi all,

Once again I would need your light. Really, I received an antenna drawing (which will go to space) made of Hard Brass. I have to perform some mechanical and thermal analysis and I had a look in my book to get the mechanical properties but I have data for the following:

Red Brass (85% Cu), Low Brass (80% Cu), Copper Brass (70% Cu) and Yellow Brass (65% Cu) but nothing about Hard Brass... Does anyone know what is the copper content of Hard Brass?

Finally, I know that Brass is TVAC compatible but I am wondering if there is some constraint while using this material (apart from corrosion cracking which I am aware of) since this is the first time I have seen it on a flight hardware.

Best regards,

Franck

 

[JStephen]

Sounds like you need to contact the drawing supplier and confirm materials, if it's critical. I don't know that those different brass terms are always used for specific percentages. They normally use the alloy numbering system to nail it down more.

 

[CountOlaf]

Perhaps if you could get the actual alloy number. e.g., red brass is C23000; low brass is C24000; etc... There's a table in Mark's Handbook extracted from the "Copper Development Association" in which I have a few more "brass" alloys with the corresponding compositions. The name alone isn't enough in this particular table.

 

[btrueblood]

Once you do have the alloy number, go to the CDA (Copper Development Assoc.) website, or enter the address below to your browser. Select "basic search", and select the alloy number from the scroll-down menu.

http://64.90.169.191/resources/properties/db/CDAPropertiesSelectionServlet.jsp

 

[btrueblood]

Oh, another thing. You may want to look at what the long-term high vacuum effects on brass are. Some alloy constituents of brass have non-negligible vapor pressures at room or slightly elevated temperatures. I.e. things like cadmium or lead may slowly evaporate from the alloy over time, resulting in these elements plating-out onto other surfaces where you'd rather they not be. Just because you can pull a "hard" vacuum for a brief time with these alloys doesn't mean their long-term use in space or in high vacuum is advisable.

 

[franck]

Thanks all to your valuable posts!

Best regards,

Franck