Actually, while I was in the Navy, at one point I was buying aluminum by the semi-load regularly. Mostly 5052H32, 6061T6, among other grades and know all about machining, welding, forming, and whatever else about it.
Aluminum requires massive amounts of electricity to manufacture, and mills usually have long-term contracts for supply of it. If this particular mill had to renew a contract for electrical power and the cost was now much higher, I can easily see that as a problem.
Back when Cali was being ass raped by ENRON and having problems getting power, ALCOA among others shut their operations down and sold California their contracted power at a profit rather than make aluminum. The price of aluminum shot up significantly.
Now, we have a Joke of a jackass in the White House that's trying to force the country to go Green with wind and solar and all that associated stupidity. That is driving the price of energy up just as it has everywhere else in the world it's been tried.