I had always just assumed the hubs on my 1970s Raleighs were steel, but now I'm not so sure. These hubs are a dull silver and have the usual stamping on them, plus the parallel line geometric pattern designs around the text. I have a couple older hubs around from the 1960s which are plainer and obviously are chrome. The chrome is much shinier than the 70s hubs are, even though they're all AW. I haven't weighed them, but the 1970s ones seem lighter. Were these 1970s era AW hubs steel or some kind of alloy? Or is the finish just different?

Sturmey Archer did make aluminum alloy hub shells in the 50's, but I don't know if they were still being made as late as 1970. The ones I've seen had the word "ALLOY" stamped on them.

Try a magnet on 'em?

Mike, put a magnet to it.
Someone may have substituted an alloy SA hub, but I doubt any came alloy stock. Weren't some very early SA hubs alloy, "racing model" as well as the obvious later ones?
Maybe someone bead blasted it, or it came as an alternate finish.
I've not seen anything other than shiny chrome on AW's in the 70's, but I'm in Texas.

If someone put one of those 'hub polishers' on the hub, the friction may have significantly dulled the chrome.

It's steel alright-- the magnet stuck like glue. Go figure though-- the finish is very different throughout the hub. It's very matte compared to the shiny chrome on the earlier hubs. It feels by hand to weigh less too. I wonder if they skimped a bit and made the shell a little thinner.