This may have been suggested before, but I was just thinking about it.
Right now, steel is effectively the best weapons-grade material besides cotton candy. Unfortunately, on maps without flux, it is next to impossible to make it in bulk (I've put in requests for max amounts of flux stones, and ONLY flux stones, and gotten like 4 in a caravan). So, I was thinking, what about having Titanium as an alternative? The idea would be that it is lighter than steel (though not as light as cotton candy), which means it would be better (in game mechanics terms, at least) than steel for cutting weapons, but wouldn't be as good for blunt ones. In terms of armor, it would be lighter but more easily cut through than steel (again, not really realistic, but it balances the two). Possibly, after making a titanium bar you could cut it with iron to make a material that is in the middle of pure titanium and steel.
The way this could be done is using rutile or ilmenite as a base, which are then mixed with one unit of coke and unit of salt (which could be distilled from salt water at a still). This could be combined into one process, or it could be made into Titanium tetrachloride and put in a vial, as well as a unit of sodium in another vial, which would then be combined to make the final titanium bar (I'm thinking one reaction would make more sense though). Although this isn't strictly how it works in real life, we add coke to turn pig iron into steel, so I'm thinking that it isn't that big a deal.
Anyway, I feel like the addition of this would add more complexity (see: dwarfiness) to the game, as well as provide a reasonable alternative to having to find flux stone in order to make steel products.
A few ideas that have come up in the thread:
-One main detraction from this is that it isn't reminiscent of the late medieval period the game is in. I would personally parry that by saying that dwarves would have more knowledge of the Earth than humans, but you can take it or leave it.
-Real life titanium requires a certain amount of technology that is simply not in the game, namely electricity. It was suggested that this could be a use for alchemy (catalyzing electrolysis). Also, impure titanium (titanium that is just what is already present in iron ore) could be created without electrolysis in theory.