What is the annealing and normalizing of large cast steel, and what is the difference between them, today you briefly describe the Dingxin casting annealing and normalizing in the role of steel castings. Annealing is the process of heating steel castings above Acs 20~30. C heat preservation process for a certain period of time. The purpose of annealing is to eliminate columnar crystal, casting in coarse equiaxed structure and dendritic segregation, to improve the mechanical properties of cast steel. Microstructure of annealed carbon steel: hypoeutectic cast steel is ferrite and pearlite, eutectoid cast steel is pearlite, hypereutectic cast steel is pearlite and carbide. Applicable to all grades of cast steel. Normalizing is to heat the cast steel to Ac. Above 30~50. C heat treatment process by which it is completely austenitizing and then cooled in still air. The purpose of normalizing is to refine the steel structure so that it has the required mechanical properties and can be used as a preparatory treatment for subsequent heat treatment. There are two differences between normalizing and annealing process. One is normalizing heating temperature is higher, the other is normalizing cooling more quickly. The strength of normalized cast steel is slightly higher than that of annealed cast steel, and its pearlite microstructure is finer. General engineering carbon steel and parts of large, large and complex shape alloy steel castings, normalizing treatment. Normalizing can eliminate the eutectoid steel and steel castings in hypereutectoid mesh carbide, in order to spheroidize; can be used as a preliminary treatment in carbon steel and alloy steel before quenching, with fine grains and uniform microstructure, thereby reducing casting defects in the quenching.
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