18-8ステンレス鋼中の酸化物系介在物に関する研究

抄録

A study was carried out on the deformation of oxide inclusions in various 18-8 stainless steels containing 0.01-4.91% Si and 0.42-1.92% Mn. The changes of inclusions from amorphous to crystalline by hot working or heat treatment were discussed. The results are as follows:
(1) When the content of manganese in steels is higher, the degree of deformation of inclusion increases with the silicon content, because most of the inclusions changes from MnO-Cr₂O₃ to mangano-silicate with increasing silicon content. In the case of lower manganese content in steel, however, the degree of deformation of inclusion is not so largely varied within the silicon content range of this experiment.
(2) The inclusions in the as cast specimens containing about 1.0% Si and 0.5% Mn, is mainly amorphous, but are changed to spinel type MnO-Cr₂O₃ by heat treatment or hot working.
(3) X-ray diffraction indicates that the inclusions in the as cast specimens containing about 1.0% Mn and 1.0% Si or about 1.8% Mn and 1.0% Si, are changed from an amorphous state to rhodonite (MnO-SiO₂) by hot working or heat treatment.
(4) As the chemical compositions of inclusions remain constant through their changes from amorphous states to crystalline one, these changes are considered to be due mainly to the crystallization of inclusions by heating.