Characterization of Nonmetallic Inclusions of Al-Killed Ca-Treated Steels by Automated SEM/EDS and Its Application to Industrial Case Studies

Abstract

Given their potential to significantly affect steel shops, production capacity and also to impair the properties of steel in service, nonmetallic inclusions are highly undesired. In this context, the availability of accurate methods to assess the steel cleanliness at different stages of the refining process is of paramount importance for the development of sound and consistent metallurgical practices. In the current contribution, a measurement tool based on scanning electron microscopy/energy-dispersive X-ray spectrometry analysis is applied to characterize the nonmetallic inclusions population (e.g., density, size distribution solid fraction, and chemical composition) present in lollipop steel samples withdrawn at different stages of the fabrication process. Data collected from a large number of samples are used to verify the reproducibility of the results and to improve the accuracy of the methodology developed. Subsequently, the characterization procedure is applied to assess the effect of different industrial aspects, such as the influence of vacuum degassing on the inclusionary panorama and the role of inclusions chemical composition on steel castability.