中间坯快冷技术对Q345A厚板表层组织和性能的影响

Effects of Intermediate Billet Cooling on Surface Microstructure and Property of Q345A Steel Heavy Plate

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 intermediate billet cooling on surface microstructure and property of Q345A steel heavy plate were investigated by the methods of thermal and numerical simulation,mechanical property testing and metallographic examination.The results show that the ultrafine ferrite microstructure with average grain size of 1 μm can be obtained on 2 mm surface layer while a little pearlite phase disperses in it.The matrix microstructure consists of massive ferrite and pearlite which is similar to that of the sample manufactured by the conventional TMCP.The matrix mechanical property,low temperature toughness will not be decreased by intermediate billet cooling.And the hardness on surface is a little more center of steel.Compared new TMCP（with intermediate billet cooling） with conventional TMCP,the steel has excellent crack arrest property.