Normalization:
Purpose: The main purpose of normalizing is to refine grain size, homogenize carbide distribution, and eliminate internal stress. ‌
Method: Heat the workpiece to 30-50 ℃ above the Ac3 or Ac1 temperature, hold for a period of time, and then cool it in air. ‌
Effect: The structure after normalizing is finer than that after annealing, and is commonly used to improve the cutting performance of materials or as the final heat treatment for some parts with low requirements. ‌
Annealing:
Purpose: The main purpose of annealing is to bring the internal structure of the metal to or near equilibrium, eliminate internal stress, and improve the plasticity and toughness of the material. ‌
Method: Heat the workpiece to an appropriate temperature, hold it for a period of time, and then slowly cool it down. ‌
Effect: The annealed material has lower hardness and is suitable for preparing for subsequent processing and final heat treatment. ‌
Quenching:
Purpose: The main purpose of quenching is to improve the hardness and strength of the material, but it also increases its brittleness. ‌
Method: Heat the workpiece above the critical temperature, keep it warm, and then quickly cool it down. ‌
Effect: The quenched workpiece has high hardness but high brittleness, and is commonly used to improve the hardness and wear resistance of tools, bearings, etc. ‌
Tempering:
Purpose: The main purpose of tempering is to reduce internal stress, decrease brittleness, and adjust the mechanical properties of the workpiece. ‌
Method: Heat the quenched workpiece to a certain temperature, hold it for a period of time, and then cool it down. ‌
Effect: Tempering can eliminate internal stress caused by quenching and reduce brittleness, while adjusting hardness, strength, plasticity, and toughness, making the workpiece more stable during use.
Each heat treatment process has its specific application scenarios and effects, and choosing the appropriate process depends on the properties of the material and the required product performance.