镁处理对FH40级船板钢中夹杂物及组织特征影响

Effect of Mg Treatment on Characteristics of Inclusions and Microstructure in FH40 Ship-Building Steel

摘要: 采用SEM-EDS研究了Mg处理钢中典型夹杂物特征，采用金相显微镜研究了Mg处理钢铸态和轧态显微组织特征。研究结果表明，FH40级船板钢经镁处理后，钢中夹杂物由Al₂O₃ + MnS逐渐变质成MgO•Al₂O₃ + MnS，随着镁处理强度的增加，变质趋于完全。未经镁处理FH40级船板钢铸态组织以“块状铁素体 + 珠光体”混合组织为主，镁处理后，铸态组织逐渐演变为“块状铁素体 + 珠光体 + 针状铁素体”的混合组织，且随镁处理强度的增加，针状铁素体数量明显升高。未经镁处理FH40级船板钢轧态组织以“铁素体 + 少量珠光体”混合组织为主，随着镁处理强度的增加，块状铁素体数量明显降低，铁素体条尺寸减少，且分布更为均匀，出现了大量针状铁素体和粒状贝氏体组织。

Abstract: The chemical composition and morphology of particles were investigated with SEM-EDS; and the characteristics of casted and rolled microstructure were characterized with OM methods. The re-sults show that, the typical inclusions are turned to be Al-Mg-O + MnS and MgO•Al₂O₃ + MnS from Al₂O₃ + MnS after adding magnesium content from 8 × 10⁻⁶ to 26 × 10⁻⁶. The main microstructures of FH40 ship-building casted steel are pearlite and polygon ferrite. However, after adding trace magnesium, the casted microstructure evolved into pearlite, ferrite and acicular ferrite, and with increasing the magnesium content, the number of acicular ferrite is obviously increased. Meanwhile, the main microstructures of FH40 ship-building rolled steel are polygon ferrite and a few pearlite. Moreover, with increasing the magnesium content, the number of polygon ferrite decreases, and the ferrite grains are refined and the distribution of ferrite is even more uniform. Further, there is large quantity of acicular ferrite and granular bainite with magnesium addition.