采用热模拟技术、力学性能测试技术和金相分析技术研究了中间坯快冷技术对Q345A厚板表层组织和性能的影响。结果表明:经过中间坯冷却+回温轧制后,在距钢板表层2mm内获得细化的铁素体组织,晶粒平均直径在1μm左右,弥散分布着少量珠光体。基体组织和常规TMCP轧制态相似,是块状铁素体与珠光体整合组织。中间坯快冷技术不会降低钢板基体的力学性能和低温韧性,钢板表层的硬度略高于心部。与常规的TMCP工艺相比,钢板具有良好的止裂能力。 The effects of rapid cooling technology on surface microstructure and properties of Q345A slab were studied by means of thermal simulation, mechanical property test and metallographic analysis. The results show that the fine ferrite structure is obtained within 2mm from the steel surface after the intermediate billet is cooled and rolled back. The average grain diameter is about 1μm, and a small amount of pearlite dispersively distributes. Matrix structure and conventional TMCP rolling state is similar to the bulk ferrite and pearlite integrated organization. Fast cooling technology in the billet does not reduce the mechanical properties of the steel substrate and low temperature toughness, hardness of the surface of the steel sheet slightly higher than the heart. Compared with the conventional TMCP process, the plate has a good anti-cracking ability.