commercial brass - is there a specification?

[rmetzger]

We are running into a number of manufactures that are spec'ing "commercial brass" as the material for fasteners. We've been able to get a loose chart of material composition (wide percentage ranges) for what they are calling "commercial brass" but no real standard from which it was derived.

any insight?

thanks

 

[MikeHalloran]

I was once associated with buying brass extrusions, specified as 'leaded brass', with a CDA number, whatever it is, I forget. Nominally 3 pct lead for improved machinability.

We got a great price from a Mexican supplier, but the stuff had a funny color, didn't braze real well, and left some odd byproducts in the brazing furnace. In pursuit of an unrelated problem, we had some assayed... >16 pct lead. No wonder it machined so well.

If you don't specify a standard, and/or don't check for what you do specify, you are the legitimate prey of unscrupulous suppliers.



Mike Halloran
Pembroke Pines, FL, USA

 

[israelkk]

Leaded brass is usually CDA360 or as called C36000

 

[btrueblood]

see

http://www.copper.org

or drilling deeper,

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

 

[TVP]

You should be specifying any brass fasteners according to an international standard such as ASTM F 468 (

http://www.astm.org/Standards/F468.htm)

otherwise this is the situation that occurs. FYI, this standard covers three brass grades among 15 copper-based alloys:

UNS C27000, Alloy 270, brass
UNS C46200, Alloy 462, naval brass
UNS C46400, Alloy 464, naval brass

Chemical composition, mechanical properties, and other requirements are outlined in this standard.

 

[OrkleYoozer]

Our supplier of "Commercial Brass" sent us a catalog page (minus the name of who the catlog was from)that listed this material as being a composition of 60-65% copper, 35-40% Zinc, .05-.15% Lead with these mechanical properties: 55,000psi tensile strength, a yield strength of 35,000psi, and an approximate hardness of B60 (which I am guessing is Rockwell B60 & not a Brinnell scale). I looked through the CDA's listing of UNS alloys and found that both C27200 and C27400 do fill the composition requirements and can meet the mechnical prperties if hardened to the correct specification. I had looked at C27000, C46200,& C46400, but they can fall outside our vendor's stated specification.