That is why it is called an assumption. If it was a listed or known we would state it as a fact.In that case, I have the perfect solution for everyone: Call it Plexcrete.
A lot of your ideas about hull (such as changing it's resistance properties) although interesting seem to be based on this assumption. I don't see that stated in the Wiki though, and I don't make that assumption myself.
https://starmadepedia.net/wiki/Hull
It could be made out of aircraft grade aluminum or it could be titanium. Simply chose steel because of the abundance of Iron available in the real universe it could be whatever they want in starmade that is the most abundant here. The point was it was given as an example. Because last I checked we don't mine iron or carbon or anything of the sort in this game to make it real. We could be however just calling it another name.
The point is elements have properties and when combined differently produce different stuff. Which this entire games crafting system is about to start with so why not make as much out of it and put in some realism on that direction if you are going to give real world names like concrete ...crete or something.