Research on the Preparation and Mechanism of Ultrafine Crystallization of 20 Steel by Strong Spinning

The ultrafine crystallization of 20 steel can make it have higher tensile strength, corrosion resistance and thermal stability. Therefore, it is widely used in the fields of medical instruments, aerospace and passenger vehicle manufacturing. However, the development of spinning technology has been limited in the theoretical research stage. In this paper, the tube 20 steel is taken as the research object, and the ultra-fine grain forming process based on "three pass strong spinning - heat treatment - two pass common spinning - heat treatment" is proposed. On the basis of spinning process test, the ultimate thinning rate of this method is explored, and the evolution rule of its surface microstructure is analyzed by metallographic microscope. The results show that the multi pass spinning with small and medium thinning makes the grain structure elongate along the axial and tangential directions, and then refine. The uniformity of the axial fiber structure was improved. The research results are of great scientific significance to reduce the consumption of high-performance metals, improve the utilization rate and properties of materials, and promote the development of preparation technology of ultrafine grained metals.