Effect of MgO on structure and crystallization behavior of CaO–SiO_(2)–Al_(2)O_(3) inclusions in Si–Mn deoxidized steel  

作　　者：Qi Xu Yao-qing Meng Jian-li Li 

机构地区：[1]The State Key Laboratory of Refractories and Metallurgy,Wuhan University of Science and Technology,Wuhan,430081,Hubei,China [2]Hubei Provincial Key Laboratory for New Processes of Ironmaking and Steelmaking,Wuhan University of Science and Technology,Wuhan,430081,Hubei,China [3]Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education,Wuhan University of Science and Technology,Wuhan,430081,Hubei,China

出　　处：《Journal of Iron and Steel Research International》2024年第11期2774-2787,共14页钢铁研究学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.52274341 and 51974210).

摘　　要：To avoid coarse crystallization of glassy inclusions in Si–Mn deoxidized steel during hot rolling, the effect of MgO on the structure and crystallization behavior of CaO–SiO_(2)–Al_(2)O_(3) inclusions was investigated. The results showed that the crystallization temperature of the oxide melts decreased with increasing MgO content from 0 to 15.7 wt.%, which suggested that the addition of MgO would increase the temperature range of the crystalline transition. The increase in MgO content could decrease the crystallization activation energy of inclusions. With the increase in MgO content, the relative fractions of O_(Si)^(0) and O_(Si)^(1) structure units increased, and those of structure units O_(Si)^(2), O_(Si)^(3), and O_(Si)^(4) decreased, increasing the depolymerization degree of the silicate structure. The crystallization ratio of glassy inclusions in the steel crucible increased from 19.7% to 98.3% with increasing MgO content from 0 to 15.7 wt.%. The addition of MgO improved the crystallization ability of inclusions, because MgO provides free oxygen O_(2−) to destroy the bridging oxygens and form non-bridging oxygens O^(−), which depolymerizes silicate network structure and simplifies the [SiO_(4)]-tetrahedral structure. In addition, MgO would promote the precipitation of the Mg-containing phases with a high melting point. When the MgO content was increased above 12.1 wt.%, MgO·Al_(2)O_(3) and 2MgO·SiO_(2) crystalline phases would precipitate from the inclusions.

关 键 词：Si-Mn deoxidized steel Glassy inclusion STRUCTURE Crystallization PLASTICIZATION 

分 类 号：TG142[一般工业技术—材料科学与工程]