中文摘要：

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·Al2O3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Al2O3＋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Zr02夹杂，该类夹杂物被MgO·Al2O3包裹，团聚现象明显．

英文摘要：

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 A1203 completely translated into MgO.Al2O3, and the size of inclusions decreased obviously. With 0.03% Zr addition, the main inclusions of the ingot were mainly A1203 ＋ MnS, A1-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, ZrO2 inclusions wrapped with MgO. A1203were found in the high Mg ＋ high Zr treated steel with the apparent tendency to be aggregated.