Category: Heat Treatment

Normalizing is a process of heating about 30–50°C above higher critical point for the time duration of 15 min and cooling in still air. The purposes of the process normalizing are: (a) to reduce grain size of steel, (b) to remove internal stress caused by working, and (c) to improve some of the mechanical properties.…

The time–temperature–transformation curves correspond to the start and finish of transformations which extend into the range of temperatures where austenite transforms to pearlite (Figure 24.2). Above 550°C, austenite transforms completely to pearlite. Below 550°C, both pearlite and bainite are formed and below 450°C, only bainite is formed. The horizontal dotted line that runs between the two…

Iron–carbon (Fe–C) phase diagram shows the solubility of carbon in iron at different temperatures and corresponding structure of the steel. For describing the Fe–C phase diagram, the equilibrium between Fe and Fe–C is considered as metastable. The larger phase field of γ-iron (austenite) compared with that of α-iron (ferrite) reflects the greater solubility of carbon, with a…

Heat treatment is a process to control the mechanical properties of engineering materials by heating, cooling, and alloying the metal as per requirement. It deals with change in properties by alloying different elements to the metal at various temperatures. The various mechanical properties such as hardness, toughness, ductility, machinability, and grain refinement are controlled by…