The evolution of oxide inclusions during isothermal heating of 18Cr-8Ni stainless steel with yttrium addition at temperatures of 1273 to 1573 K was investigated systematically. Homogeneous spherical Al-Y-Si(-Mn-Cr) oxide inclusions were observed in as-cast steel. After heating, most of the homogeneous inclusions were transformed into heterogeneous inclusions with Y-rich and Al-rich parts, even though some homogeneous oxide particles were still observed at 1273 and 1573 K. With the increase in heating temperature, more large-sized inclusions were formed. The shape of the inclusions also changed from spherical to irregular. The maximum transformation temperature of inclusions was determined to be 1373 K. The evolution mechanism of inclusions during heating was proposed to be the combined effect of the (i) internal transformation of inclusions due to the crystallization of glassy oxide and (ii) interfacial reaction between inclusions and steel matrix. Meanwhile, the internal transformation of inclusions was considered to be the main factor at heating temperatures less than 1473 K.

系统地研究了添加钇的18Cr-8Ni不锈钢在等温加热过程中氧化物夹杂物的演变。在铸钢中观察到均匀的球形Al-Y-Si（-Mn-Cr）氧化物夹杂物。加热后，即使在1273和1573 K处仍观察到一些均匀的氧化物颗粒，大多数均质夹杂物也转变为具有富Y和富Al的异质夹杂物。随着加热温度的升高，更大尺寸的夹杂物形成了。夹杂物的形状也从球形变为不规则形。夹杂物的最高转变温度确定为1373 K. 提出了加热过程中夹杂物的演化机理是（i）玻璃态氧化物结晶导致的夹杂物内部转变和（ii）夹杂物与钢基体之间的界面反应的综合作用。同时，夹杂物的内部转变被认为是加热温度低于1473 K时的主要因素。