Abstract: 30SiMnMoVA is a widely used structural steel material in structural parts of automobiles and tractors. The heat treatment process of 30SiMnMoVA was studied in this article. The microstructure and properties of 30SiMnMoVA through the heat treatment process before and after the normalizing process and tempering process were studied by optical microscope, SEM and X-ray diffraction. The results showed that, after the normalizing process, the pearlite and high-temperature ferrite phases were formed in the microstructure of 30SiMnMoVA. After the tempering process, the pearlite/ferrite phases present in the matrix could be consolidated, and the mechanical properties of the material increased significantly by refining the microstructure.
There are many kinds of structural steel materials that have been widely used in the current industry, 30SiMnMoVA is a typical structural steel material, which has been widely used in structural parts of automobiles and tractors. It has many advantages such as good comprehensive mechanical properties, good cold and hot forming properties, weldability and ease of machinability. However, in order to obtain such excellent performance, heat treatment is required to refine the microstructure and form the proper interphase.
In order to get a reasonable arrangement of the phase structure of 30SiMnMoVA, a reasonable heat treatment process is essential. The heat treatment of 30SiMnMoVA mainly includes normalizing process and tempering process. The normalizing process can improve the homogeneity performance of the steel, thereby significantly improving the mechanical properties of the material. The tempering process can further improve the overall performance of the material by refining the grain structure and improving the mechanical properties. In this experiment, the heat treatment process of 30SiMnMoVA was studied. The microstructure and properties of 30SiMnMoVA through the heat treatment before and after the normalizing and tempering processes were studied by optical microscope, SEM and X-ray diffraction.
The samples of 30SiMnMoVA were normalized at 1000℃ for 5 hours and then cooled in the air, and then the samples were tempered at 350℃ for 2 hours and then cooled in the air. In order to ensure the high accuracy of the sample, the sample was annealed at 900℃ for 1 hour and then cooled in the air before the experiment. The microstructure of 30SiMnMoVA was observed by optical microscope, SEM and X-ray diffraction. The properties of materials were tested by hardness and tensile strength.
The results showed that, after the normalizing process, the pearlite and high-temperature ferrite phases were formed in the microstructure of 30SiMnMoVA, which had a particle size of 1 μm~2 μm. The formation of the pearlite, with a larger particle size, gave the material good comprehensive mechanical properties. After the tempering process, the pearlite/ferrite phases present in the matrix could be consolidated, and the mechanical properties of the material increased significantly by refining the microstructure. The test results show that the hardness of the material after tempering is 8.6 HRA, the tensile strength is 1020Mpa and the yield strength is 950Mpa. This is far above the standard requirements for 30SiMnMoVA materials, indicating that the heat treatment process has significantly improved the comprehensive mechanical properties of 30SiMnMoVA materials.
In conclusion, the heat treatment of 30SiMnMoVA has a certain effect on its mechanical properties. The normalizing process can improve the homogeneity performance of the steel, and the tempering process can further improve the overall performance of the material by refining the grain structure and improving the mechanical properties. Through the normalizing process and tempering process of 30SiMnMoVA, its comprehensive mechanical properties have reached the standard requirements, proving the success of the experiment.
