Improving cleanliness of 30Cr2Ni4MoV low-pressure rotor steel by CaO-SiO_(2)-MgO-Al_(2)O_(3) slag refining  

作　　者：Yong-bo Peng Cheng-song Liu Ling Yang Song-wei Hou Ri-jin Cheng Hua Zhang Hong-wei Ni 

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]Huangshi Product Quality Supervision and Inspection Institute,Huangshi 435000,Hubei,China

出　　处：《Journal of Iron and Steel Research International》2022年第9期1434-1445,共12页

基　　金：supported by the National Natural ScienceFoundation of China(Grant Nos.51774217,52074198 and51604201).

摘　　要：The optimal composition of a CaO-SiO_(2)-Al_(2)O_(3)-MgO slag in the ladle furnace refining process was investigated to precisely control the contents of[0]and[Si]and improve the cleanliness of 30Cr2Ni4MoV steel.The iso-[O]lines and iso-[Si] lines of the equilibrium between the CaO-SiO_(2)-Al_(2)O_(3)-MgO refining slag and 30Cr2Ni4MoV steel at 1873 K were calculated by the thermodynamic software FactSage 7.3,and the activities of SiO_(2),Al_(2)O_(3)and CaO in the refining slag were discussed to achieve the optimal composition range of the refining slag.Finally,combined with high-temperature"slag-steel"equilibrium experiments,the effects of different refining slags on the oxygen contents,chemical composi-tions,quantities and sizes of inclusions in steels were studied,and then the thermody namic formation mechanism of MgAl_(2)O_(4) inclusions in 30Cr2Ni4MoV steel was discussed.The results showed that the contents of dissolved[O]nd[Si]in steel can be controlled below 10 × 10^(-6)and 0.05%.respectively;when the slag basicity is above 7.the CaO/Al_(2)O_(3)ratio is above I.and the mass fraction of SiO_(2)in the slag docs not cxcced 7%.The chemical composition of the slag has a great influence on the removal and composition of inclusions.The assessed stability phase diagrams of MgO.Al_(2)O_(3)and MgOAl_(2)O_(3) inclusion formation in the Fe-Al-Mg-O system calculated by FactSage 7.3 show good agreement with the experimental results.

关 键 词：30Cr2Ni4MoV steel Non metallic inclusion Refining slag BASICITY CaO/Al_(2)O_(3) ratio 

分 类 号：TF4[冶金工程—钢铁冶金]