Effects of Deformation Penetration and Recrystallization on the Internal Quality of Casting Ingot

To investigate the influence of rolling passes on the internal quality during high-temperature reduction pretreatment (HTRP), three cast ingots with identical total reduction but varying numbers of rolling passes are prepared. The 3D distribution, size, and quantity of defects are analyzed using ultrasonic nondestructive microscopy. The effect of rolling passes on defect healing is studied, with macrostructure, microstructure, and grain size analysis aided by finite element software. In contrast to the three-pass HTRP, the one-pass HTRP demonstrates a diminishment of 7% in defect dimensions and a notable decline of 66% in the quantity of defects. The results reveal that increasing the number of rolling passes leads to a deterioration in internal quality of the slab. Reducing the number of rolling passes improves internal strain penetration, facilitates the recrystallization process, and enhances the microstructure uniformity, ultimately improving the internal quality.