Steel in 1868: Open-hearth

The iron–carbon workhorse of buildings, ships, rails and tools — endlessly recast. Steel is one of 32 materials in this atlas, grouped under metals: history, structure, measured properties, process routes, uses, safety and market — not a product catalogue. Scores compare Steel with the rest of the atlas on strength, heat, fire behaviour, insulation, workability and circularity. They are editorial, not certificates.

Seven chapters follow. Fire and insulation claims name test families (Euroclass, ASTM E84, ISO 5660, KS F) rather than inventing a single safety number. Steel (Fe–C (±Mn, Si, Cr…)) is a family of grades whose density 7.85 g/cm³, heat band 1370–1530 °C, and fire letter A1 as construction steel.

Steel is sold as grades, not as a single substance. Chemistry Fe–C (±Mn, Si, Cr…), density 7.85 g/cm³, heat band 1370–1530 °C. This atlas treats Steel as a system: mill route, coatings, tests and the cavity it sits in. Conductivity note: ~50 W/m·K. Insulation score 8/100 is relative to 32 entries — metals lose, VIPs and aerogels win.