Abstract: The roles of inclusions MnS, Al₂O₃ and Al₂O₃·MnS in the formation nucleation of intragranular ferrite were studied by means of the plysical simulation method. The microstructures of the micro-zone adjacent to the inclusions were observed with metallurgical microscope and the chemical compositions of the micro-zone adjacent to the inclusions were analyzed with an electron probe mircoanalyzer. The results show that inclusions MnS, Al₂O₃ and Al₂O₃·MnS can not change the chemical composition of the metai micro-zone adjacent to the inclusions. The MnS and Al₂O₃·MnS have an ability to induce the nucleation of intragranular ferrite, but the Al₂O₃ has no potential for nucleating intragranular ferrite during the thermal cycle. The MnS in compound inclusions Al₂O₃·MnS plays an important role in the formation nucleation of intragranular ferrite.

Key words: intragranular ferrite, physical simulation, inclusions