On 2018-08-08 14:48:54
Application of normalizing in heat treatment
Normalizing is similar to annealing, which has the following characteristics: high mechanical properties, easy operation, short production cycle and less energy consumption, so normalizing should be selected as much as possible.
Normalizing has the following applications
1. Heat treatment of common structural parts;
Normalizing can eliminate the overheating defects in casting or forging production, refine the structure and improve the mechanical properties.
2. Improve the machinability of low carbon steel and low carbon alloy steel;
The metal with hardness of 160 ~ 230hb is easy to cut and has high metal hardness. It is not only difficult to process, but also easy to wear and tear the tool. The energy consumption is also large. The hardness is too low. It is easy to stick the tool when processing, which makes the tool heat and wear, and the surface finish of the processed parts is also poor. Shadow indicates that the machining performance is better and the annealing hardness of low carbon alloy steel is generally below 160hb, and the machinability is poor. However, normalizing (1-point scribe line) is selected. Due to the increase of pearlite volume, the spacing between layers becomes smaller, so the machining performance is improved.
3. Pre heat treatment of main parts made of medium carbon structural steel;
Normalizing is often used to pre heat treat important parts. For example, normalizing the medium carbon structural steel can change some abnormal structure into normal structure, eliminate the structure defects caused by hot working, and it has a positive effect on reducing the quenching deformation and cracking of workpieces and improving the quenching quality.
4. To eliminate the net secondary cementite in hypereutectoid steel and to prepare for spheroidizing annealing, this is because the normalizing cooling rate is relatively fast and the secondary cementite can not be separated out along the a grain boundary.
5. For some large or complex parts, quenching may have the risk of cracking. Normalizing often replaces quenching and tempering treatment as the heat treatment of these parts.