How is the heat treatment temperature determined for the restored mechanical properties of Q345R after cold working? What is the basis?

The heat treatment temperature for Q345R is typically determined by a combination of factors such as the material’s chemical composition, microstructure, and the requirements of its actual application. Typically, the heat treatment temperature range for Q345R is between 850 and 1200 degrees Celsius. This range is based on the phase transition points of steel and their impact on mechanical properties. The main purpose of heat treatment is to eliminate the residual stresses introduced during cold working and to improve the microstructure, thereby enhancing the mechanical properties of the material, such as hardness, toughness, and strength. By selecting the appropriate temperature and cooling rate, ideal mechanical properties can be achieved. As for the specific heat treatment temperature, it needs to be determined through experiments. That is, heat treatment is carried out at different temperatures, and then the mechanical properties after treatment, such as tensile strength, yield strength, and reduction of area, are tested in order to determine the optimal heat treatment temperature. Furthermore, the heat treatment process also needs to take into account the limitations of the equipment, such as the maximum operating temperature of the heat exchanger, which can affect the determination of the heat treatment temperature. In summary, determining the heat treatment temperature for restoring the mechanical properties of Q345R after cold working requires taking into account factors such as the material’s properties, the required mechanical properties, and equipment limitations, along with the results of experimental tests. Therefore, selecting the heat treatment temperature requires extensive experience and specialized knowledge. .

This post was last edited by Take a look_knkRj on 2023-11-3 at 16:11. The definition of 150 refers to the recrystallization temperature, which can be found in many materials textbooks. Additionally, I’m attaching a post; regarding the issues with the header manufacturers mentioned by the original poster in that post, I’m not aware of them either. However, what was said on floor 13 seems to make some sense, and it needs further verification: https://bbs.hcbbs.com/thread-1175120-1-1.html (Source: Haichuan Chemical Industry Forum)

It’s the same as the condition of the material at the time of manufacture. If it comes in as hot-rolled steel, then it goes through 620 stress relief treatment; if it comes in as normalized steel, then it undergoes 920 normalization treatment