I've been thinking about something, and it may be nothing more than 'meeble' to add to Iron Stars, but being of an engineering bent, I submit the following for your consideration:
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Structural and Armoring Metals in Iron Stars:

Copper

Brass

Monel

K-Monel

Aluminum

Siliconized Aluminum Alloy

Iron Plate

Wrought Iron

Mild Steel

Chrome Steel

Alloy Steel

Krupp Plate

...the above are actual metals...below are additions....

WasserStahl - Metastable Beryllium

Wasserstahl II - Stabilized Lithium/Beryllium Alloy

Hypersteel - Gravitically Enhanced Steel, denser than normal

UberStahl - Gravitically Enhanced Wasserstahl

Adamantine - Uberstahl/Hypersteel Alloy

....I had some other stuff in mind, but I can't always find a pen when I'm brainstorming.