In addition, normalizing helps reduce internal stresses induced by such operations as forging, casting, machining, forming or welding. Normalizing imparts both hardness and strength to steel work-piece. Normalizing is normally done for several reasons such as (i) to modify and / or to refine the grain structure and to eliminate coarse grained microstructure got in previous working operations such as rolling and forging etc., (ii) to modify and improve cast dendritic microstructure and reduce segregation by homogenization of the microstructure, (iii) to produce a homogeneous microstructure and to get desired microstructure and mechanical properties, (iv) to improve machinability of low carbon steels, (v) to improve dimensional stability, (vi) to reduce banding, (vii) to improve ductility and toughness, (viii) to provide a more consistent response when hardening or case hardening, and (ix) to remove macro-structure created by irregular forming or by welding.įine grained pearlite is tougher than coarse grained pearlite. To be properly classed as a normalizing heat-treatment, the heating portion of the process is required to produce a homogeneous austenitic phase (face-centered cubic, or fcc, crystal structure) prior to cooling. Typically, the work-piece is heated to a temperature around 30 deg C to 80 deg C above the upper critical line of the iron-iron carbide phase diagram, i.e., above Ac3 for hypo-eutectoid steels and above Acm for hyper-eutectoid steels. In the thermal sense, normalizing is an austenitizing heating cycle followed by cooling in still or slightly agitated air. Normalizing of steel is a heat-treatment process which is frequently being considered from both thermal and microstructural standpoints. The aim of the normalization process is to get a fine-grained, uniformly distributed, ferrite-pearlite microstructure. The purpose of the treatment is to remove the effects of any previous heat treatment (including the coarse-grained microstructure sometimes resulting from high forging temperatures) or cold-working and for ensuring a homogeneous austenite on reheating for hardening or full annealing. Normalizing is a process in which a steel is heated, to a temperature above the Ac3 temperature or the Acm temperature and then cooled in still air. annealing, austenite, CCT, Ferrite, heat treatment, microstructure, normalizing, pearlite ,.
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