Abstract: The 20Mn23AlV billet（/%：0.04~0.12C，≤0.50Si，21.50~25.00Mn≤0.030P，≤0.030S，1.50~2.50Al，0.04~0.10V）produced by continuous casting process is prone to edge cracks during hot rolling, which seriously affects the normal production. Through the analysis of chemical composition and scanning electron microscopy, it is confirmed that the edge cracking of plate is caused by AlN inclusion and mold slag entrapment. In the third brittle temperature range, AlN precipitates at the austenite grain boundary, which decreases the binding energy of austenite grain boundary, and then reduces the plasticity of steel; because of the high manganese content in steel, the columnar crystal structure is serious during solidification, and transgranular structure and cracks are easy to form; Slag entrapment occurs in the continuous casting process, and the inclusions involved in the billet have different ductility with the matrix, and cracks occur with the rolling process. Therefore, the process parameters of steelmaking and continuous casting are optimized, which reduces the number of AlN inclusions in steel and the frequency of flux entrainment in molten steel, and the edge cracking rate of plate is reduced from 28% to less than 3%.

Key words: 20Mn23AlV, inclusions, edge cracks