Physicalchemistry of formation of oxysulfide inclusions in steels

最近一个新的过程已经开发出来控制gamma·alpha转化钢使用MnS precipitates on the oxide inclusions as nuclei。按顺序优化化合物的含量，MnO-SiO_2-MnS系统在温度范围从1473 K到1723 K进行了调查，MnS在MnO/（MnO+SiO_2）中的增加率和显示出在0.6的比率中的粗糙增加率，哪一个是一致的，在氧化物金属过程中MnS的最大预处理率。An oxysulfide compound composed of 8 MnO·3 SiO_2·MnS was newly found as a stable solid phase at lower temperature than 1573 K. It has been considered that this phase is formed via the peritectic reaction between 2 MnO·SiO_2 and liquid phase。分析各种化合物饱和度在几个温度下的组合物，以及MgO·SiO_2·MnS系统估计的相位图。最后，氧化物包括在内的MnS抑制剂的机制已经受到了质疑。Fe-Ti-Mn混合物的equilibrium组合物和那些共同存在的氧化物也被调查了在1873年使用一种冷的危险。氧化物的含量被分解，因为增加了锰和钛的内容，对更重要的latter的影响。锰具有相同含量的金属，对他们的钛含量无管制，是相等的氧化物，具有MgO和FetO的恒定活性比率。使用金属组合物和吉布斯能量的形成，MgO、FetO和TiO-在1873 K<1.5>对MnO-FetO-TiO_<1.5>melts进行了评估。使用Ti-Mn合金的实用消除过程的最佳条件已被讨论。

Recently a new process has been developed to control the gamma・alpha transformaion of steels using MnS precipitates on the oxide inclusions as nuclei. In order to optimize the composition of inclusions, phase relations for the MnO-SiO_2-MnS system have been investigated at temperatures ranging from 1473K to 1723K.The solubility of MnS increased with an increase in MnO/(MnO+SiO_2) ratio and showed a drastic increase at the ratio of 0.6, which was consistent with the maximum precipitation ratio of MnS in the oxide metallurgy process. An oxysulfide compound composed of 8MnO・3SiO_2・MnS was newly found as a stable solid phase at lower temperature than 1573 K.It has been considered that this phase is formed via the peritectic reaction between 2MnO・SiO_2 and liquid phase. Deliberating the compositions of liquids saturated with various compounds at several temperatures, the phase diagram for the MnO・SiO_2・MnS system has been estimated. Finally, the mechanism of the MnS precipitation in the oxide inclusions has been discussed.The relationship between the equilibrium compositions of Fe-Ti-Mn melts and those of coexisting oxides were also investigated by employing a cold crucible at 1873 K.The oxygen content decreased with increasing the contents of manganese and titanium, the effect of the latter being significant. The metals which had the same contents of manganese, regardless of their titanium contents, were equilibrated wiht molten oxides having a constant activity ratio of MnO and FetO.Using the metal compositions and Gibbs energies of the formation of component oxides, iso-activity contours of MnO,FetO,and TiO_<1.5> for the MnO-FetO-TiO_<1.5> melts at 1873K were evaluated. The optimal conditions for practical deoxidation processes with Ti-Mn alloys were discussed.