1 Heat treatment is a process that changes the internal structural domain of a solid metal by heating and cooling it and obtains the desired properties. The heat treatment in the manufacturing process of the product can be divided into individual opinions according to its main purpose, which can be divided into post-weld heat treatment, hydrogen elimination treatment, recovery, or heat treatment to achieve specified mechanical properties.
2 For carbon steel and low-alloy steel products, due to the large deformation caused by cooling, significant cooling work hardening will occur, which will increase the strength, hardness, plasticity and toughness of the material, and at the same time, it will also generate a large internal stress. . In actual production, the product is heated to a temperature below 50° C. to 150° C. below AC1, and the slow cooling process of the aged boiler after proper insulation is used to eliminate the stress annealing. As the atomic activity increases with increasing temperature, the grains that are broken during cooling and are crushed by the elongated fire gradually become uniform and fine equiaxed grains through the process of nucleation of new crystals and growth of nuclei.