Metallurgy: Ductile to Brittle Transition in Steel

This lecture discusses the mechanical properties of metals, focusing on the ductile to brittle transition in steel. The instructor explains the significance of the Charpy impact test, which measures the energy absorbed during fracture at different temperatures. The lecture covers the microstructural characteristics of steel, including the effects of carbon content on its properties. The instructor elaborates on the phases of iron and their transformations, emphasizing the role of interstitial carbon atoms in influencing the mechanical behavior of steel. The discussion includes the impact of temperature on the ductility of steel, highlighting the critical temperature at which the transition occurs. The lecture also addresses the historical context of this phenomenon, referencing incidents during World War II that underscored the importance of understanding material properties. The instructor concludes by discussing practical implications for engineering and material selection, particularly in civil engineering applications where steel is commonly used.