What is the normalizing process for forgings based on?

What is the normalizing process of shaft forgings according to?

Normalizing process heating steel for Ac3 (ACM) over 30? 50 ℃, the heat preservation after the right time, in the stillness of the air cooling heat treatment process. Steel heated to 100? More than 150 ℃ Ac3 normalizing is called high temperature normalizing. For medium and low carbon steel casting, forging, normalizing the main purpose is to refine the structure. Compared with annealing, normalizing pearlite flake is fine and ferrite grain size is small, so it has higher strength and hardness. Low carbon steel, because of low hardness annealing, produce cutting adhesion knife phenomenon, poor cutting performance, through normalizing to improve the hardness, can improve cutting performance, some carbon structure steel parts in normalizing can replace air conditioning, simplify the heat treatment process.

Hypereutectoid steel is hot knife ACM above, so that the original network cementite absorption to austenite, and then use faster cooling, inhibit cementite precipitation in the austenite grain boundary, so as to eliminate the network carbides, improve the structure of hypereutectoid steel. The welding strength requirement of welding parts is to improve the weld structure and ensure the welding strength.

In the heat treatment process must be standardized, maintenance parts of the mechanical properties of the structural parts must be normalizing air conditioning to meet the requirements of mechanical properties. However, high alloy steels and large forgings must be tempered at high temperature to add and eliminate the internal stress caused by normalizing. Some alloy steel forgings produce martensite phase transitions and hard microstructure formation.

In order to eliminate the abnormal tissue to normalizing, than normal normalizing temperature 20 ℃ or so higher the normalization of heat insulation. The normalizing process is simple, which is beneficial to forging heat in the fire, and can save energy and shorten the production cycle. Normalizing treatment also produces tissue defects, improper operation, annealing is similar, and the remedy is basically the same.