Why Use Alloy 4047 for Hermetically Sealed Housing Covers

[dingpud]

OK, 4047 Aluminum is used for housing covers which are hermetically sealed using a laser welding process. Can anyone give me a reason why this specific alloy is used?

Some spec on the alloy:
http://www.jlanthonyandcompany.com/product/4047_aluminum.html

I would figure if you had a housing that was 6061 which is typical, you would want to weld the same alloy to it, but apparently not. Any ideas would be helpful.

Thanks,

 

[montoyas7940]

I am not sure exactly why in your application. But I do know that silicon is also used in aluminum Mig wire. I think it improves the filling properties.

 

[dingpud]

Interesting. Maybe the 4047, typically being found as thin pieces of stock resists burn through...

Who knows...probably someone trying to sell the stuff mentioned about how it "needed" to be used for housing covers, and that's been the industries rule of thumb ever since.

Thx.

 

[Enthalpy]

Al-Si alloys have a lower melting point. Using Al-Si as a filling alloy avoids to melt the base material, so it deforms less. It's more soldering than brazing then.

Was this your question?

 

[dingpud]

Maybe, so the 4047 contains Si in it's chemical composition, whereas something like 6061 doesn't... This allows the housing 6061 to stay, for the most part, in tact, while the cover 4047 is fused into the housing...

Yeah, if the above statement is true, then yes, that answered the question.

Thanks.