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For certain applications, coarse titanium nitride (TiN) precipitates can be deleterious for the final properties of the material. Hence, in order to better understand the mechanisms involved in the generation of these precipitates, a thorough characterization of the particles observed in steels with different titanium and nitrogen content was carried out. Samples from liquid steel (tundish), continuous casting billets and final product were evaluated using an Automatic Particle Analyzer (APA) coupled to a Scanning Electronic Microscope (SEM). The location, frequency, size distribution and composition of the different particles observed were assessed. While only few TiN precipitates were observed in liquid steel samples, the density of this type of particle significantly increased in the continuous casting billets samples. Particles ranging from 1 to 10 μm were mainly found in the interdendritic zones of the as-cast structure. The density of TiN particles observed in these samples did not change after reheating and rolling operations. A model to predict TiN precipitation during solidification was developed. A reasonable agreement was found between model results and measured data. Results of this analysis confirmed that the precipitated fraction of TiN increases as the product of steel Ti and N contents rises.

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(e.g., density, size distribution solid fraction, and chemical composition) present in lollipop steel samples withdrawn at different stages of the fabrication process.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.

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