Steel is one of the basic resources in Factorio. It deserves to have its own proper production chain.

This mod expands the steel production chain by requiring a carbon source to produce a steel mixture, which is then smelted into steel. Later technology allows for more efficient recipes, including casting molten steel.

Carbon Steel Expanded does not aim to make steel production overly complex. There are no new buildings, technologies, or lengthy production chains. Instead the goal is to add some flavor to steel production while staying as ‘vanilla friendly’ as possible, keeping the recipes simple but fun. The main challenge comes from more pressure on your early coal supply, and more involved logistics.

Steel mixture from coal
Throw some iron and coal together for a steel mixture that can be smelted in any furnace. It’s janky and inefficient, but it gets the job done.

Steel mixture from carbon
Carbon is moved up in the tech tree and is now available after unlocking Sulfur Processing. Throw it together with some iron into a refinery for some less janky and more efficient steel mixture.

Molten steel
We’re no longer magically casting steel from just molten iron. Add some carbon to it for molten steel and use a foundry to cast it into plates.

Low density structures casting
LDS is now cast with molten steel, as it should be.

Recycling
Steel plates recycle back into steel mixture. Steel mixture itself cannot be recycled by default, but there’s a setting to change that if you desire (I realized this could be a PITA on Fulgora).

Credits
Based on the original mod by Djohaal.
Steel mixture graphic is a recolor from Krastorio.

AI disclosure
Code for this mod was largely written by Claude Code, after which it was verified and fully play tested by me. This mod will be maintained for the foreseeable future.