Physics/How usable is titanium in building space habitats?
So I was wondering about using titanium as a building material for space habitats in the future. Steel has been suggested by Gerald O'Neill in the book ''The High Frontier: Human Colonies in Space'' to build O'Neill Cylinders six and a half kilometers in diameter and thirty two kilometers long.
However I have heard that titanium would allow us to build even bigger space habitats, if only theoretically building at least, at twenty kilometers in diameter and a hundred kilometers long.
But how usable is titanium anyway as a building material for space habitats? As I have heard, titanium is brittle in cold temperatures such as those found in space. And I have also heard that the amount of titanium that would be needed to melt together would be really hard to put together.
So how usable is titanium truly as a building material in space habitats and spacestations?
Titanium is used in the International Space Station - although only for certain applications. It is not used for the habitat enclosure apparently. I don't know a reason that it could not be. (I am not a metallurgy expert.) A new welding technique is being used by the Navy to build a full sized ship (my source doesn't give the size).
I don't see a reason that the larger size habitat would be less feasible if made of steel. The problem would be getting the material into space. I suspect that the reason for the increase in potential size of the habitat you discussed is the weight savings from use of titanium. Titanium's advantage would be in the decrease of the energy required to lift the material from the Earth's surface.
I hope this helps,