钢热处理中的标准化和回火之间有什么区别？

　Difference between normalizing and tempering in steel heat treatment

　　The purpose of normalizing is similar to complete annealing for hypoeutectoid steel, but due to the rapid cooling rate of double annealing, the number of pearlite in the steel after normalizing is slightly more than that of annealing, and the thickness of the sheet is thin. The strength and hardness are higher than those of annealing. For hypereutectoid steels, normalizing is only to eliminate reticulated cementite and improve the mechanical properties of the steel. Tempering is mainly to eliminate stress, stabilize the structure and size of steel parts, and achieve the required performance of parts. For large-section parts: It has the following effects-and it is very important:

　　1) For parts such as motor shafts, press containers, etc. (the material is generally carbon steel or low alloy structural steel), normalizing + high temperature tempering is the final heat treatment. Therefore, timely tempering after normalization can effectively stabilize the organization And size to further eliminate the internal stress of the workpiece, which has a significant effect on improving the comprehensive mechanical properties;

　　2) For large-scale forgings, high-temperature tempering in time after normalizing (usually adding a subcooling in the middle) can not only achieve the purpose described above, but also play an important role in hydrogen diffusion, especially for high hardenability steel (Hydrogen is a factor that produces white spots), and large white forgings are generally scrapped if white spots are generated inside. Therefore, normalizing + high temperature tempering of important parts (or special materials) is very necessary. When materials with good hardenability are normalized, high temperature tempering is required, because after normalizing, materials with good hardenability have higher hardness, such as:20CR.2NI4,18CR2NI4W等。需要高温回火。主钢等级：T2 T11 T12 T22 T23 T91 2CR13，15crmo.，15crmog，12Cr1mov.G，R102 T92

锅炉钢需要正常化和回火。回火主要是为了使结构稳定，使其可以具有一定的高温耐久性，蠕变强度和高温和压力的耐用性。事实上，正常化后的回火是国外的一个非常常见的事情。相反，正常化后不会回火是一个特殊情况。为了降低中国的生产成本，在正常化条件下，一半的性能不会回火。

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