For steel plate supply, what exactly is the type of tempering involved in normalizing followed by tempering?
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In the supply conditions of steel plates, quenching and tempering as well as normalizing + tempering are commonly encountered. According to the heat treatment terminology GB/T7232, quenching and tempering refers to quenching plus high-temperature tempering; the type of tempering in this process is clearly high-temperature tempering； For that steel plate, when it is specified as normalized + tempered, what type of tempering is meant by that? According to the available information (Figure 3): high-temperature tempering takes place at 500–650°C, medium-temperature tempering at 350–500°C, and low-temperature tempering at 150–250°C. Based on the usual principles, when stress-relief heat treatment is applied and the raw material is supplied in a normalized+tempered state, the temperature for stress-relief heat treatment should be 30°C lower than the tempering temperature of the raw material; otherwise, it is considered that the normalized+tempered state of the raw material is compromised. (Figs. 2, 4, 5) Compared with the temperature ranges for the previous three tempering processes, it can be seen that the stress-relief heat treatment, which is specified to be 30°C lower than the tempering temperature of the raw material, can only refer to high-temperature tempering. Therefore, in the normalizing+tempering process applied to the steel plates at the time of delivery, does the tempering step refer solely to high-temperature tempering, or are there other types as well? Are there any relevant standards and sources for this analysis?
The tempering step mentioned in the supply condition of steel plates, as part of the \"normalizing + tempering\" process, can actually refer to different temperature ranges depending on the application scenario and material requirements. Generally, the normalizing + tempering treatment is intended to achieve a good balance between toughness and strength. Normalizing refers to heating to an appropriate temperature and holding it there, followed by cooling in air, in order to achieve the desired mechanical properties. Tempering is carried out after normalizing or quenching, and it is used to eliminate internal stresses, reduce hardness, and improve toughness. In various industrial applications, the tempering temperature for normalizing + tempering can be selected from the low-temperature, medium-temperature, or high-temperature tempering ranges as needed. Therefore, there is no fixed definition stating that the tempering in “normalizing + tempering” must refer to high-temperature tempering. It could be high-temperature tempering, medium-temperature tempering, or even low-temperature tempering, depending on the desired material properties and application area. Regarding the specific standards and sources, GB/T 7232 is the standard for terms related to metal heat treatment, but it may not specify detailed temperature requirements for the \"normalizing + tempering\" process for each type of material. To determine the exact tempering category for a specific material and application, it is usually necessary to consult the relevant material standards or industry standards, or to look up the specific heat treatment specifications provided by the material supplier. In practice, unless otherwise specified, the tempering category for the normalized + tempered condition of the steel plates supplied is usually specified in the material specifications, or it is necessary to confirm this with the supplier. Regarding the heat treatment requirements for specific applications, engineers determine which type of tempering to use based on the performance requirements of the material and the actual operating conditions, and provide clear heat treatment specifications during design and manufacturing. If stress-relief heat treatment is to be carried out, and the principle that \"the temperature for stress-relief heat treatment should be 30°C lower than the tempering temperature of the raw material\" must be followed, it is necessary to know the exact tempering temperature of the raw material in order to select the appropriate treatment method. .
Why doesn’t the original poster simply check the GB/T713 standard? It’s written clearly there.
The material standards specify the tempering temperature, if tempering is required