镁处理船板钢热循环过程中组织的细化机制研究  

Study on Microstructure Refinement Mechanism of Magnesium Treated Ship Plate Steel during Thermal Cycling

作　　者：李明达 孙立根 马振云 王博 雷鸣 LI Mingda;SUN Ligen;MA Zhenyun;WANG Bo;LEI Ming(College of Metallurgy and Energy,North China University of Technology,Tangshan 063210,China;Hebei Engineering Research Center of High Quality Steel Continuous Casting,Tangshan 063210,China;Hegang Group Tangshan Iron and Steel Troup Co.,Ltd.,Tangshan 063600,China)

机构地区：[1]华北理工大学冶金与能源学院,河北唐山063210 [2]河北省高品质钢连铸工程技术研究中心,河北唐山063210 [3]河钢集团唐山钢铁集团有限公司,河北唐山063600

出　　处：《热加工工艺》2023年第8期145-151,共7页Hot Working Technology

基　　金：国家自然基金青年项目(51804125);河北省钢铁联合基金项目(E2021209083);河北省教育厅青年拔尖人才项目(BJ2018013)。

摘　　要：为了研究镁处理船板钢在热循环过程中组织细化的机制以及第二相粒子析出的规律,采用高温激光共聚焦显微镜(CLSM)对镁处理船板钢的热循环过程中显微组织的变化进行动态原位观察,并通过扫描电镜(SEM)、能谱仪(EDS)和金相显微镜(OM)研究不同冷却速率下诱发IAF的夹杂物演变规律。并从错配度的角度,分析IAF在夹杂物上的形核机制。结果表明:试验条件下,镁处理试验钢中的钉扎粒子能够有效抑制奥氏体晶粒的粗化,并且在降温阶段,钢中夹杂物能够诱发出IAF,有效细化组织。对于试验钢而言,降温速率为5℃/s时,夹杂物对IAF的诱发效果最佳。能够诱发IAF的夹杂物的核心是在钢液脱氧合金化过程中形成,夹杂物表面的MnS是在焊接热循环过程中二次析出附着于复合夹杂物表面,这也从理论上验证了夹杂物的扫描电镜分析结果。In order to study the mechanism of microstructure refinement and the second phase particle precipitation of magnesium treated ship plate steel during thermal cycling,the dynamic in situ observation of the microstructure change of magnesium treated ship plate steel during thermal cycling was carried out by high temperature laser confocal microscope(CLSM).The inclusion evolution rule of IAF at different cooling rates was studied by scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS)and optical microscopy(OM).The nucleation mechanism of IAF on inclusions was analyzed from the angle of misfit degree.The results show that the pinning particles can effectively restrain the austenite grain coarsening under the experimental conditions,and the inclusions can induce IAF and effectively refine the microstructure at the cooling stage.As for the experimental steel,the effect of inclusion on IAF is the best when the cooling rate is 5℃/s.The core of the inclusion that can induce IAF is formed during deoxidation and alloying of liquid steel,and the MnS on the surface of the inclusion is secondary precipitated and adhered to the surface of the compound inclusions during the welding thermal cycle,the results of SEM analysis of the inclusions are also verified theoretically.

关 键 词：镁处理船板钢 原位分析 夹杂物构成 诱发IAF 错配度理论 

分 类 号：TG166.4[金属学及工艺—热处理]