Uploaded December 2025 | Updated September 2026, 2 weeks ago
A detailed overview of a part of the solid-state portion of the iron-carbon (Fe-C) phase diagram, which is fundamental to understanding steel metallurgy. It explores the historical development of steel science, highlighting the foundational discoveries of early researchers like Tschernoff and Osmond, who established critical transformation temperatures. The document also addresses unresolved thermodynamic issues within the diagram, such as whether cementite or other carbides (like χ and η) represent true equilibrium states, concluding that the experimental evidence favors cementite as the stable phase. Furthermore, the author advocates for the routine inclusion of the T_0 curve on the phase diagram, arguing that it holds the same thermodynamic significance as other equilibrium boundaries. Finally, the text discusses the supersaturation of carbon in bainitic ferrite, explaining this phenomenon by considering the equilibrium between body-centered tetragonal ferrite and austenite rather than the standard body-centered cubic ferrite.
Slides: phase-trans.msm.cam.ac.uk/2025/FeC.pptx
A detailed overview of a part of the solid-state portion of the iron-carbon (Fe-C) phase diagram, which is fundamental to understanding steel metallurgy. It explores the historical development of steel science, highlighting the foundational discoveries of early researchers like Tschernoff and Osmond, who established critical transformation temperatures. The document also addresses unresolved thermodynamic issues within the diagram, such as whether cementite or other carbides (like χ and η) represent true equilibrium states, concluding that the experimental evidence favors cementite as the stable phase. Furthermore, the author advocates for the routine inclusion of the T_0 curve on the phase diagram, arguing that it holds the same thermodynamic significance as other equilibrium boundaries. Finally, the text discusses the supersaturation of carbon in bainitic ferrite, explaining this phenomenon by considering the equilibrium between body-centered tetragonal ferrite and austenite rather than the standard body-centered cubic ferrite.
Slides: phase-trans.msm.cam.ac.uk/2025/FeC.pptx
