What is normalizing?
Zoe Jia
2023-11-02 09:04:26
Fire, also known as normalization, is to heat the workpiece to Ac3 (Ac refers to the final temperature at which all free ferrite is converted into austenite during heating, generally between 727 °C and 912 °C) or Acm (Acm is the critical temperature line of complete austenitization of eutectic steel in actual heating) 30~50 °C above, and after holding warm for a period of time, the metal heat treatment process is taken out of the furnace and cooled in the air or sprayed with water, spray or blowing. The aim is to refine the grains and homogenize the carbide distribution. The difference between normalizing and annealing is that the normalization cooling rate is slightly faster than the annealing cooling rate, so the normalizing structure is finer than the annealed structure, and its mechanical properties are also improved. In addition, the external cooling of the normalizing furnace does not occupy equipment, and the productivity is high, so normalizing is used as much as possible instead of annealing in production. For important forgings with complex shapes, high temperature tempering (550-650 °C) is also required after normalizing, and the purpose of high temperature tempering is to eliminate the stress generated during normalizing cooling and improve toughness and plasticity.