Steel production is fairly complex compared to the creation of other alloys, which only involves one step to combine bars of different pure metals to create the final product. With a cunning-enough starting build, it is possible to embark with enough coal boulders to produce several hundred units of coke, but only if your parent civilization has access to coal otherwise, it will not be available at all. Note that bituminous coal and lignite, like most stones, cost only 3☼ at embark or from caravans.

Charcoal requires more labor per unit than coke, but is often easier to acquire. If you embark in a forest biome, you can produce thousands of units of wood from the surface trees alone, without even tapping into the caverns.

charcoal from wood, or coke from imported bituminous coal or lignite.

marble from metamorphic layers, or imported flux.

hematite from igneous extrusive layers, or iron ore imported from trade caravans, or melting iron items brought by siegers ( goblinite) and caravans.

If you have no sedimentary layers at your fortress site, your only hope to make steel is with: Furthermore, four of the five flux stones (calcite, chalk, dolomite, and limestone) are found only in sedimentary layers, as well as both coal ores (bituminous coal and lignite). The three ores of iron (hematite, magnetite, and limonite) can only be found in sedimentary layers, with the exception of hematite, which can occasionally be found in igneous extrusive layers. The end result is steel: iron with just the right amount of carbon in it. Flux is used to remove impurities, including carbon, during the smelting process, while fuel (charcoal or coke) removes oxygen and puts back in a small amount of carbon.

To smelt steel, you will need iron bars, flux stone, and fuel.

Dwarf fortress pig iron