also varied.The inclusions are changed into globular form.Nonmetallic inclusions type (Al2O3.Y2Os).S and Y2O2S.(Fe,Mn)S appeared.Scanning electron mi- croscopic analysis of inclusions indicates that content of yttrium in complex inclusions is varied from 6~8%to 60~70%due to increase of added amount of modificator.Fig.4 shows that distribution of Y and S inside the studied nonme- tallic inclusions.Moreover the concentration of elements appears uniformly inside inclusions.Size of containing yttrium inclusions is not more 300um. 3 Conclusions Metallic melt with yttrium causes modification of nonmetallic inclusions in the melt.Inclusions in the conparative steel are oxides and sulfides,but inclusions in the steel,which was finished with yttrium,are complex oxisulphides.Not only the inclusions morphology is varied,but the inclusions size is also changed.It is established that a little amount of yttrium (Y]/CS]<3)has insignificant effect of modification.This is coincided with results of well-known researches. Yttrium can act as a deoxidizer and a desulfurizer simultaneously.Products of reaction of oxygen and sulphur in the melt with added yttrium are the origin of complex nonmetallic inclusions. The further developed research is necessary because of limited experiment data in a short days. Acknowlegement:The authers are grateful to the colleagues of Steelmaking Division USTBEIJING for their friendly help in the course of the study. REFERENCES 1 Averin VV.Proc.Metallurgicheskie Methody Povyschenia Ka- fchestva Stali,Izd.Nauka,1979;33 2 Maltsev M V.Modifitsirovania Structury Metallov i Splavov Jad.Meta- 11 ur gia,1964;213 3 Tiagunov G V,Ystnhuk.Trudy M Konferentsii po Slitku Izd.Metallu- rgia,1978,98 4 Du Ting,Wang Longmei.J.Less Common Metals,1985;110:179 5 Du Ting,Wang Longmei.Proc.of Inter.Conf.On RE Developm:ent and Applications,Beijing,PRC,Sept.10~14 1985;Vo1.II,1238 543一 · · · · ， · · 一 · 人 。 · ‘ 火 。 ， ， ， 五 · ， ， 一 〔 〕 〔 〕 。 一 。 。 五 了 丁五 五 几 、 。 。 夕 存 夕 口少 ， ， 一 介 “ ， ， · 硬 · 宕 ， ， · ， 门 ， 一 一 · ， ， ， 。 一 ·