Mg-Zr处理对FH40级船板钢铸态夹杂物特征的影响

采用定量金相及SEM-EDS手段对Mg，Zr及Mg-Zr处理FH40级船板铸钢中夹杂物粒径分布、平均粒径、总数量、总面积及成分、形貌等特征进行系统研究.结果表明，Mg，Zr及Mg-Zr处理后铸锭夹杂物平均粒径下降，夹杂物总数量增加.Mg的质量分数为0024%时，夹杂物中MgO平均质量分数为1257%，变质不充分；Mg的质量分数增加至0072%后，夹杂物中MgO平均质量分数为3558%，实现了氧化铝向MgO·Al2O3的充分变质，且夹杂物粒径明显减小.003%Zr处理后，铸锭夹杂物以Al2O3+MnS，Al-Zr-O+MnS为主；低Mg+高Zr，高Mg+低Zr，高Mg+高Zr处理炉次试验钢铸锭中均发现了含Zr夹杂物，其中高Mg+高Zr炉次形成了ZrO2夹杂，该类夹杂物被MgO·Al2O3包裹，团聚现象明显.

Effects of Mg Zr Combined Treatment on Characteristics of Inclusions in FH40 Ship Building Steel Ingots

The characteristics such as particle size distribution， average particle size， total amount and chemical composition of FH40 ship building steels formed by Mg， Zr， Mg Zr combined treatment were investigated by the quantitative metallographic and SEM EDS methods. The results showed that the average particle size decreased while the total amount of inclusions increased after Mg， Zr， Mg Zr treatment. With 0024%Mg addition， the average mass fraction of MgO was 1257% in the inclusions， which was not fully modified； With 0072%Mg addition， the average mass fraction of MgO was 3558%， in the inclusions which meant that Al2O3 completely translated into MgO·Al2O3， and the size of inclusions decreased obviously. With 003% Zr addition， the main inclusions of the ingot were mainly Al2O3+MnS， Al Zr O+MnS. The Zr containing inclusions were all found after Mg Zr combined treatment with the amount of the Mg and Zr additions changed as follow low Mg+high Zr， high Mg+low Zr and high Mg+high Zr. Especially， ZrO2 inclusions wrapped with MgO·Al2O3were found in the high Mg+high Zr treated steel with the apparent tendency to be aggregated.