基于同步辐射的硫系易切削钢中MnS夹杂物形态演变三维表征及调控机制研究

高品质易切削钢是高端制造业发展的重要依托，MnS夹杂物的形态调控是生产高品质易切削钢的关键问题。夹杂物尺寸和形态表征是明晰其形态演变和调控机制的基础依据。目前MnS夹杂物形态演变的研究主要基于样品剖面中夹杂物尺寸和形态的定性观察和统计。然而MnS夹杂物形状不规则，二维观察具有较大偏差，无法建立准确的数学模型阐明其形态演变机制，因而MnS夹杂物形态演变和调控机制尚未完全明晰。本项目提出利用同步辐射光源X射线显微CT对钢中MnS夹杂物三维尺寸和形态进行参数化定量表征，搭建高温原位动态观察实验装置，实现热处理过程中MnS夹杂物形态演变的原位表征；结合热力学计算、扫描电镜和电子探针微区成分分析，查明凝固、轧制和热处理工艺对MnS夹杂物形态的影响规律，构建其形态演变的数学模型，阐明MnS夹杂物形态演变和调控机制，为钢中MnS夹杂物形态调控提供基础依据。本项目对提升易切削钢品质具有重要的现实指导意义。

The developing of high-end manufacturing industry is largely dependent on the high-quality free-cutting steel. The morphological regulation of the MnS inclusions is a key issue for producing high-quality free-cutting steel. The investigation of the morphological evolution and regulation mechanism is largely based on the characterization of the morphology of the MnS inclusions. The research works on the morphological evolution mechanism of MnS inclusions mainly focused on the two-dimensional qualitative observation and statistics of the size and morphology of the inclusions in the cross sections of the sample. However, two-dimensional observation deviates from the fact due to the irregular morphology of the MnS inclusions, which could not accurately model the morphological evolution of the inclusions. Thus, the mechanisms of the morphological evolution and regulation of the MnS inclusions have not been clarified clearly. In this project, the three-dimensional size and morphology of the MnS inclusions are quantitative characterized by using the X-ray Micro-CT at the synchrotron radiation facility. An in-situ observation device is built in the beamline at the synchrotron radiation facility to characterize the in-situ morphological evolution of the MnS inclusions during heating at high temperatures. With the assistance of the thermodynamic calculation, Scanning Electron Microscopy (SEM) and Electron Micro Probe Micro-Analysis (EPMA), mathematical models would be built up for the morphological evolution of the MnS inclusions based on the investigation of the influence of solidification, rolling and heating on the morphology of the MnS inclusions. The models would contribute to clarify the morphological evolution and regulation of the MnS inclusions, which would greatly contribute to fundamentals of the morphological regulation of MnS inclusions and improve the properties of sulfur bearing free-cutting steel.