Course Notes:

This lecture covers the principles of mechanical metallurgy focusing on the mechanisms of cold working and annealing in materials. The objective is to explain the effects of dislocation movements and how they influence the mechanical properties of metals. The methodology involves reviewing temperature effects on the stress-strain curve, discussing the role of dislocation climb in ductility enhancement, and delineating the stages of annealing which include recovery, recrystallization, and grain growth. Results show that cold working increases tensile strength and yield strength while decreasing ductility, alongside notable changes in electrical conductivity and chemical reactivity. In the recovery stage, there is a restoration of physical properties without structural changes, while recrystallization replaces the cold worked structure with new strain-free grains, effectively reducing dislocation density and restoring ductility. The lecture emphasizes the non-fixed nature of recrystallization temperature depending on multiple influencing factors. This thorough analysis provides insight into the complex behavior of materials under mechanical stress and subsequent treatment processes.