Uniformity of performance of Q355B steel plate based on the ultra-fast cooling process

The performance uniformity of low alloy Q355B steel plate under ultra-fast cooling process was analyzed and the reliability of the process was verified by mechanical properties test and metallographic examination at different positions of longitudinal and transverse. The results show that the strength and toughness of the steel plate head were slightly higher, but the yield strength, tensile strength, elongation and impact toughness of the steel plate were ≤ 40 MPa, ≤ 19 MPa, ≤ 4.0% and ≤ 35 J, respectively, the steel plate had good performance uniformity. There were differences in the microstructure of the upper and lower surfaces of the steel plate, indicating that the cooling capacities of the upper and lower surfaceswere different, it was necessary to increase the flow rate of the lower header to compensate the heat transfer capacity of the lower surface, so that the cooling in the thickness direction was uniform.