Forum Contributor 2017
Honestly why check it? I'm going to play the H e l l out of it and see if parts start flying off.Oh pooh. So much misinformation here.
There are hundreds of aluminum alloys. There are dozens of aluminum alloys used in aircraft. There is NO SUCH THING as "aircraft grade aluminum". Go to "Matweb" and look up Aluminum alloys for an education.
I suppose it's possible to weld aluminum to steel, but it would be expensive and complicated due to the very great difference in melting points. I'm willing to bet you that you do NOT have spot welds of Al to Fe in that ligature. It's far more likely that the band is sheet Al, spot welded to bar Al for the two bars (and the whole thing's probably 6061 T6 as this is one of the very most common alloys and offers good strength, weldability, formability, and machinability).
The colored anodizing is one of the most common finishes for aluminum. There is NOTHING special about it for at least the last 50 years.
The posters who said "make sure and keep the threads well lubricated" are correct, it's even more critical if the screws are Al (there's no need on earth to use Al screws, they're actually a much worse choice in 99% of applications than plain old Zn plated steel, or even brass, and galling of Al and Al is a very serious problem). I will add that if the screws are Al, you should use antiseize or molybdenum disulfide lubricant in preference to plain oil. You've got high pressure slow speed sliding motion there, the perfect condition for thread galling, and plain oil is pretty weak in EP lubricating properties. I'd check the screws to see if they're Al or Fe, I bet they're Fe.