不同洁净度条件下253MA钢中夹杂物的析出行为

基于多相多组元反应平衡原理及凝固过程固液相界面的溶质再分配理论，建立了253MA钢凝固过程中夹杂物析出与溶质元素偏析的耦合热力学模型，并验证了模型预测的准确性.在本模型计算条件下，253MA耐热钢中析出的夹杂物主要为Ce2O3，Ce2O2S，Ce3S4，CeS，CeN，SiO2，MnS.当氧的质量分数低于0006%时，Ce2O3夹杂析出的条件为［%O］/［%S］＞1；当氧的质量分数高于0006%时，Ce2O3夹杂析出的条件为［%O］/［%S］＞2.当氧的质量分数低于00046%时，若［%O］+［%S］＞0009，则耐热钢中可以析出Ce3S4，而CeN夹杂无法析出；若［%O］/［%S］＜1，则钢中可以析出CeS夹杂，且随着硫的质量分数的增加，CeS逐渐向Ce3S4转变.当氧的质量分数高于00046%时，CeN夹杂析出的条件为2［%O］+［%S］＜0014.

Precipitation Behavior of Inclusions in 253MA Steel with Different Cleanliness

A coupled thermodynamic model of inclusion precipitation and solute elements microsegregation during solidification of 253MA steel was established on the base of the reaction equilibrium principle of multiphase and polycomponent， and the redistribution theory of solute elements in the interface of liquid and solid during solidification. The accuracy of this model was validated through the commercial test and scanning electron microscope (SEM) analysis of inclusions formed in the samples. Under the rated condition， the inclusions in 253MA steel are mainly Ce2O3， Ce2O2S， Ce3S4， CeS， CeN， SiO2 and MnS. And the precipitation principles of these inclusions are obtained by this model. When oxygen content in 253MA steel is higher 0006%， Ce2O3 can precipitate if the ratio ［%O］ / ［%S］ is greater than 1. When oxygen content is lower than 0. 006%， Ce2O3 can precipitate if the ratio is greater than 2. When the oxygen content is lower than 00046%， Ce3S4 precipitates and CeN disappears if ［%O］+［%S］>0009; CeS exists in steel when ［%O］/［%S］<1 and transfers to Ce3S4 with the increase of the sulfur content. When the oxygen content is higher than 00046%， CeN can precipitate if 2［%O］+［%S］<0014.