Li Xiang, Long Xiao, Wang Linzhu, Tong Shouhao, Wang Xiutao, Zhang Yin, Li Yutang
College of Materials & Metallurgical Engineering, Guizhou Institute of Technology, Guiyang 550003, China.
School of Materials and Metallurgy, Guizhou University, Guiyang 550025, China.
Materials (Basel). 2020 Jan 30;13(3):619. doi: 10.3390/ma13030619.
In order to study the effect of Ca and sulfur contents on the characteristics of inclusions, industrial experiments using 95CrMo steel were conducted. SEM-EDS detections and stereological analysis were used to probe the characteristics of inclusions, including their compositions, morphologies, size, number density, and distribution. The results indicate that there were mainly three types of inclusions in 95CrMo steel billets with 6-18 ppm Ca and 30-100 ppm S: inclusions with single-phased morphology mainly composed of oxides; isolated MnS/CaS-only inclusions; inclusions with multi-phased morphology. The three-dimensional inclusion size distribution suggests that there were more Type-1 inclusions with a small size in low S containing steels. The average diameter of all types of inclusions increased with increasing Ca or S content in 95CrMo steel, indicating that the formation of MnS and CaS coarsened their size. The density distribution of inclusions indicates that the more inclusions there are, the more easily they aggregate and collide. Moreover, it is presumably concluded that the formation of sulfide in the outer layer of oxide inclusions weaken the attraction between oxide inclusions. The equilibrated transformation and formation of inclusions during the cooling process of 95CrMo steel was discussed based on thermodynamic calculation. The equilibrated transformation trajectory of inclusions in 95CrMo steel during the cooling process was CaSiO + MgO → CaMgSiO → Spinel + CaS, which was corresponding to the detected results. The precipitation regular of sulfide was obtained. The formation mechanism for three types of inclusions was discussed.
为了研究钙和硫含量对夹杂物特性的影响，采用95CrMo钢进行了工业试验。利用扫描电子显微镜-能谱仪（SEM-EDS）检测和体视学分析来探究夹杂物的特性，包括其成分、形态、尺寸、数量密度和分布。结果表明，在钙含量为6 - 18 ppm、硫含量为30 - 100 ppm的95CrMo钢坯中，主要存在三种类型的夹杂物：单相形态的夹杂物，主要由氧化物组成；孤立的仅含硫化锰/硫化钙的夹杂物；多相形态的夹杂物。三维夹杂物尺寸分布表明，低硫含量钢中尺寸较小的1型夹杂物较多。在95CrMo钢中，随着钙或硫含量的增加，各类夹杂物的平均直径增大，这表明硫化锰和硫化钙的形成使其尺寸变粗。夹杂物的密度分布表明，夹杂物数量越多，它们越容易聚集和碰撞。此外，可以推测氧化物夹杂物外层硫化物的形成削弱了氧化物夹杂物之间的吸引力。基于热力学计算，讨论了95CrMo钢冷却过程中夹杂物的平衡转变和形成。95CrMo钢冷却过程中夹杂物的平衡转变轨迹为CaSiO + MgO → CaMgSiO → 尖晶石 + CaS，这与检测结果相符。得出了硫化物的析出规律。讨论了三种类型夹杂物的形成机制。
