采用对钢板纵向和横向不同位置进行力学性能测试和金相检验的方法，分析了超快冷工艺下低合金Q355B钢板的性能均匀性，验证了工艺的可靠性。结果表明：钢板头部的强度和韧性略高，但钢板的屈服强度同板差≤40 MPa，抗拉强度同板差≤19 MPa，断后伸长率同板差≤4.0%，冲击韧性同板差≤35 J，钢板具有较好的性能均匀性；钢板上、下表面的显微组织存在差异性，说明上、下表面冷却能力不同，需要增加下集管流量以对下表面换热能力进行补偿，使厚度方向冷却均匀。

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.