Effect of the heating furnace time of casting slabs on the ultrasonic testing quality of medium plates

The relationships between the heating furnace time of casting slabs and the ultrasonic testing quality of hot-rolling medium plates were investigated. It is concluded that, (1) when the heating furnace time of 220 mm thickness casting slabs was less than 3 h, very bad ultrasonic testing quality of the plates would happen; (2) increasing the heating furnace time of the slabs could effectively improve the ultrasonic testing quality of the plates; (3) what caused the ultrasonic testing lost was micro-cracks in the pearlite band; (4) reducing the centerline segregation of the slabs could obviously improve the ultrasonic testing quality of the plates.