Q345A低碳钢厚板表层组织的超细化

Grain ultrafining in surface layer of Q345A steel heavy plate

用Q345A钢在实验室轧机和Gleeble3800热模拟试验机上,研究了中间坯冷却+回温的新型TMCP轧制工艺对低碳钢厚板表层组织的影响。应用TecnaiG220透射电镜观察了组织,探讨了组织细化机制。结果表明,钢板经过中间坯冷却+回温轧制后,可在距钢板表面2 mm内得到超细铁素体晶粒,晶粒平均直径在1μm左右,其间弥散分布着少量珠光体,靠近心部组织和常规TMCP轧制相似,是块状铁素体+珠光体的整合组织。表层组织超细化是多次相变细化作用的结果。

Effect of the TMCP with controlling IBCR（intermediate billet cooling ＋ re rise temperature） on microstructure of Q345A steel heavy plate in surface layer was investigated by means of Gleeble 3800 thermo-mechanical simulator and a lab rolling mill,and the formation mechanism of ultrafine microstructure was discussed.the results show that the ultrafine ferrite microstructure with average grain size of 1 μm can be obtained in depth of 2 mm while a little pearlite phase disperses in it.The microstructure near the core consists of massive ferrite and pearlite which is similar to the sample manufactured by the conventional TMCP.The multiple transformations lead to ultrafining microstructure of the surface layer.