So what you're describing actually sounds a lot like the fantasy metals that Furry Fortress has, pyrochalcum(sharp), aerochalcum(light), geochalcum(heavy), hydrochalcum(valuable), dracometal(balanced, rare) and neutronium(comically dense). There's also ironwood, an underground wood with the properties of iron, and bladebough, underground wood with the sharpness of obsidian.
My reason for including all of these things was that I was frustrated with steel-making in vanilla. It's such a rare thing to have iron ore and flux stone in the same place, and it's so hard to import them. (which is also why Furry Fortress adds the crucible steel reaction with clay and clear glass, since you can reliably import those) (It also gives the world a more fantasy feel)
I guess what I want is to allow you to make the game's strongest metal anywhere in the world (or in more places), but I still want there to be some challenge in making it, a sense of accomplishment upon producing it, better than just, "yay, I picked the right map". And to some extent, you should be free to pick a method that works best for you. Maybe you like coming up with powered Blast Furnaces, maybe you prefer the quiet zen of repeatedly folding Laminated Steel.
So, okay, as of right now, I'm thinking I make it so that iron ore cannot be processed at the smelter. You can build either a bloomery, or a blast furnace, which requires power. Bloomery produces blooms, which can be worked into wrought iron or pig iron (presumably at the same workshop, maybe at the forge, as this should require an anvil). Wrought iron + pig iron OR wrought iron + wrought iron + carbon = Pattern Weld, further work on the Pattern Weld will become Folded Steel or Laminated Steel. Blast Furnaces will produce cast iron/pig iron, which can be decarburized (stirred?) into wrought iron, or mixed into Blast Steel or combined with flux stone into Flux Steel.
Crucible steel should also be worked in, not sure if it should be done at the bloomery or the blast furnace. It would probably work like current Furry Fortress crucible steel, clay + clear glass + carbon + iron = crucible steel. Wootz could be an improved type of crucible steel, maybe from a specific ore, or from adding a certain mineral. Or, to keep a medieval European perspective, Wootz could be made for non-playable civs and can only be imported, not natively produced.
So,
Useless Tier = Cast Iron/Pig Iron, Bloom
Tier 1 = Wrought Iron
Tier 2 = Pattern Weld
Tier 3 = Laminated Steel, Blast Steel, Crucible Steel
Tier 4 = Flux Steel, Wootz
Also, I probably want to update some of my other fantasy metals to work within this system. I might have you produce Nickel in the same way as Iron, as I think that's how it works.
If anyone wants to pick over my full list of FuFo metals, here it is
Paktong = copper + nickel (50/50 cupronickel)
Bulletta = lead + antimony (bullet metal, harder than lead, heavier than antimony)
White Gold = gold + nickel
Antimonial Bronze = copper + antimony (actually probably would use arsenical bronze)
Doubloonium = gold + antimony (allegedly creates a purer gold, or would harden gold, a bit dubious)
Novachalcum = pyrochalcum + aerochalcum + geochalcum + hydrochalcum
Possibly,
Nickel Steel = nickel + steel
Mangan Steel = pyrolusite + steel
Pyrolith (ore) -> Pyrochalcum (metal) (sharp)
Hydrolith (ore) -> Hydrochalcum (metal) (valuable, can be made into clothing)
Aerolith (ore) -> Aerochalcum (metal) (lightweight)
Geolith (ore) -> Geochalcum (metal) (heavy, blunt)
Dragon Fossil (ore) -> Dracometal (metal) (bone-like, very light, but tough as metal)
Neutronium Ore (ore) -> Neutronium (~metal) (as dense as slade, supposed to be very rare, but caravans will shower you with it)
In one of the previous versions, you could use pyrochalcum + pig iron + flux + carbon = Blaze Steel, and so on for the other 3, but eventually, I found this tedious.
An idea that I never got around to was that Neutronium will bond with tetravalent elements, i.e. carbon and silicon, so Neutronium + steel = Neutron steel, Neutronium + Diamond = Neutron Crystal, Neutronium + Graphite = Neutron Paper, Neutronium + sand = Neutron Glass. My original desire was that when Neutronium ore is smelted into Neutronium metal it "explodes", rapidly lowering in density as it mixes with available impurities.
I definitely want to make Neutronium only available through custom workshops, although I'm not sure if that would make it more abundant via caravans.