D0I:10.13374/i.issm1001-053x.1989.06.025 北京科技大学学报 第11卷第6期 Vol.11 No.6 1989年11月 Journal of University of Science and Technology Beijing Nov.1989 Modification of Nonmetallic Inclusions in Steel with Yttrium' TapactoK JI.I."Cai Kaike(蔡开科)，Liu Xinhua(刘新华)， Qu Ying(曲英)· ABSTRACT:The modification affects of yttrium on formation of nonmetallic inclusions in steel has been studied by use of metallographic method.The effect of added quantity of modificater on type and size of inclusions was also studied in this work. KEY WORDS:yttrium,modification,nonmetallic inclusions A complex modification effect of yttrium on Fe-C melt has been discussed in several references[1-3).It changes the interface tension of crystal-melt boun- dary and can form the high melting combinations in the melt.Moreover,some particles in melt are able to adsorb isomorphous crystallizing grain to its surface. In this work,a different amount of yttrium has been added in the melt,and the type and size of nonmetallic inclusions were studied in order to find the optimum quantity of modificator in the melt. 1 Research Method The metal is melted in a Tamman furnace with an alumina crucible and fini- . shed with the modificator.The charge was calculated on purpose to obtain a ingot of 600g.Then the specimens were cut out by scheme as shown in Fig.1.The upper, middle and lower pieces of the half ingot were carried on the metallographic study. The specimen for chemical analysis was taken on the centreline of another half. The chemical compositions are as follows (wt%): C-0,30;Si-1.50;Mn-1.80;P-0.010;S-0.020;A1-0.083;0-0.0096. In the molten steel with above composition the different amount yttrium was Manuscript Received May 11,1989 ..Marioupol Metallurgical Institute in USSR,This work was carried out in USTB EIJING ...Dept.of Metallurgy 539、 、 第 卷第 期 年 月 北 京 科 技 大 学 学 报 丁 。 。 。 ’ 功 刀 · … ‘ 吞 蔡开 科 ， ’ ‘ “ 刘新 华 ， 夕 曲 英 ’ ‘ · 。 ， ， 、 一 〔 一 〕 一 ， ， ， · 争‘ 从 、 · 一 ， · 一 。 一 。 一 。 一 。 一 。 一 。 一 。 · 住 ， 一 ， · ， · DOI ：10．13374／j ．issn1001－053x．1989．06．025