if your civ has access to iron ore, you can request a minimum 16 units of steel per year (4 steel + 4 pig iron + 4 iron + 4 flux + 4 steel anvils).
With enough flux, you can also request the ores themselves and smelt them into more steel.
This is enough to make steel picks or axes or swords for 16-dwarf military, or weapons + helmets for 8-dwarf military.
If your civ has no iron ore, it still can magically make steel and pig iron, and some type flux can commonly be requested. Iron can then be acquired from humanite or goblinite.
Also, you can import tin, bismuth, cassiterite and bismuthnite if your civ has them. Smelting bismuth bronze yields huge amount of bars. 4 tin + 4bismuth +4cassiterite +4 bismuthinite from caravan is 64 bars of bismuth bronze, and then add 4 bars bismuth bronze and 4 bars of regular bronze from the caravan. - 72 bars is enough to armour an entire squad.
Bronze, it's not that bad against goblins' weapons.
After all, if you are not in some sort of challenge, nothing actually prevents you from safely cutting some excess blue stuff if you know what i mean. you only need 5 rock per soldier in a minimal setup (with steel breastplate, shield and weapon)
edit: miscalculation