Effect of copper in 4043

I found many manufacturers add some copper in 4043 either on purpose or involved with adding scrap. Whoever please let me know, if on purpose, why they add copper to 4043?

Thanks a lot in advance.

Hello wujunw_99,

I am not sure exactly where you are going with this because we note from your profile that you are a metallurgist with a metals and alloys company that melts and casts its own redraw rod for TIG (Tungsten Inert Gas) welding applications. We also note from your posting on 4047 aluminum alloy that your company draws the wire to size as well. Finally we note that your metals and alloys company is a division of a very large company that manufactures and sells welding equipment around the world. We therefore respectfully suggest that you should be telling us the complete answer to the question you have posed, at least from a metallurgical point of view.

As I am already completely confident that you know there can be a small amount of copper in aluminum alloy 4043. Here is the make up of 4043 alloy as I understand it:

Maximum percentages of trace elements by weight:

Silicon 4.5 - 6.0
Iron 0.8
Copper 0.3
Beryllium 0.0008
Manganese 0.05
Magnesium 0.05
Zinc 0.10
Titanium 0.20
Others Each 0.05 but not more than a total 0.15
Aluminum Balance

I am not a metallurgist but I presume that some of the alloying companies you reference are bringing the copper content up to or near the allowed specification maximum to bring the the electrical conductivity or perhaps other mechanical properties of the alloy into specification since, as I am sure you well know, the alloy is generally used as a filler wire in TIG welding. This may be done to optimize what they believe is their ideal version of 4043 welding alloy. If any of the concentrations of the alloying elements however are over the specification limits, then it is no longer 4043 alloy and it cannot be sold as such.

The electrical conductivity of 4043 alloy is 42% of copper at 68°F/20°C at equal volume or 140% of copper at 68°F/20°C at equal weight.

There seems to be a fair amount of variability in the alloy specification since we note that the concentration of alloying elements are specified as maximums and that the melting point can vary between 1065 F and 1170 F. Perhaps you would like to comment on that as well.

Sincerely,
Peter J. Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com

its added on purpose for weld quality issues. maybe talk to your jw harris division and they will tell you more about it.