Steel is a fire

Heat the steel to the critical point ( AC3, ACcm) Above, an austenite 仜 completely, and then cooled in the air, the heat treatment process, called normalizing. ( A) Normalizing process of normalizing AC3 above 50 - heating temperature is chemical composition 100℃； ACcm above 30 - hypereutectoid steel heating temperature 50℃。 Heat preservation time depends on effective thickness of workpiece and the heating furnace type, such as heating in chamber furnace, can effective thickness per mm insulation calculation in a minute. The cooling after heat preservation, generally can be cooled in the air, but a few large workpiece or at high temperature in summer, sometimes use blowing or spray cooling. ( 2) Microstructure and properties after normalizing normalizing is essentially a special case of annealing. Both differences, mainly lies in the cooling speed faster, super-cooling degree faster, thus false eutectoid transformation happens, pearl increases amount in the organization, and pearly 柋 lamella spacing is smaller. It should be noted that some of the high alloy steel after air cooling, can obtain bainite or martensite structure, this is due to the high alloy steel of supercooled austenite is very stable, C curve. , because of the organizational characteristics after normalizing after normalizing strength, hardness and toughness are higher than after annealing, and the plastic is not reduced. Normalizing the application of normalizing and annealing, compared to the mechanical properties of the steel is high, the price is simple, short production cycle, less energy consumption, therefore, with the possible conditions, priority should be given by normalizing treatment. The present application is as follows: 1. As a final heat treatment 2 common structural parts. To improve low carbon steel and low carbon alloy steel cutting machining. 3. As the important parts in carbon structural steel production of heat treatment in advance. 4. Eliminate hypereutectoid steel stroke secondary cementite, ready for the organization for spheroidizing annealing 5. For some of the larger or more complex shape parts, quenching may have the risk of cracking, normalizing tend to replace quenching and tempering treatment, and as a final heat treatment of this kind of parts. Very * right. At this point has not said it for normalizing, and is called air quenching. In order to increase the hardness of low carbon steel, can be appropriately raise normalizing temperature.