Comparison of Nonmetallic Inclusion Characteristics in Metal Samples Using 2D and 3D Methods

Abstract

The characteristics of different shapes of nonmetallic inclusions (NMIs) are determined using different methods. In this respect, various shapes of NMIs, including spherical, octahedral, elongated, bar‐like, plate‐like, polyhedral, and irregular inclusions, are observed in different steels and ferroalloys. The inclusions are investigated using three methods: 1) 2D investigations on a polished cross section (2D method); 2) 3D investigations on a film filter after electrolytic extraction and filtration (EE method); and 3) 3D investigations on a metal surface after electrolytic extraction (MS method). In addition, scanning electron microscopy (SEM) with an energy‐dispersive spectrometer (EDS) is used for the determination of the chemical composition of inclusions. The advantages and limitations of different methods for investigations of different shaped inclusions are discussed. The results show that the 2D method is less precise to detect the morphology, size, and number of inclusions; however, the EE and MS methods are used to determine a more accurate morphology. Furthermore, the MS method is found to be more advantageous in detecting large‐sized inclusions. This study also shows that the results on both the film filter and metal surface should be grouped together to obtain more comprehensive information of the inclusion characteristics.

Non-metallic Inclusions in Different Ferroalloys and Their Effect on the Steel Quality: A Review

“…Based on the investigations on the polished surface and the metal surface after extraction, the maximum length of Al 2 O 3 inclusions can reach a value of 491 lm. [47] Apart from Al 2 O 3 inclusions, some high Al 2 O 3 -containing inclusions were observed. These might be closely related to the high Al content (3 3 mass pct) in the FeV alloy.…”

“…A recent paper [47] reported that the number density of SiO 2 inclusions was about 49.5/mm À2 and that the largest inclusion reached a size of about 187 lm on the metal surface after electrolytic extraction (EE). Thus, the addition of FeSi alloys can inevitably increase the oxygen content in the steel due to the presence of a large number of SiO 2 inclusions.…”

A Review of Steel Processing Considerations for Oxide Cleanliness

“…Another SEM-based method is manual analysis of much smaller numbers of inclusions that were exposed by dissolving the steel matrix around inclusions (deep-etching). [126] This method provides better imaging of the three-dimensional morphology of inclusions (rather than 2D sections), at a higher resolution (using secondary electron imaging), but with much more time needed to image one inclusion. The main advantage of the automated SEM-based method is that hundreds of measurements of micro-inclusion section size (and shape) and chemical composition can be obtained in tens of minutes, when using a fast EDS detector.…”

Interfacial Phenomena and Inclusion Formation Behavior at Early Melting Stages of HCFeCr and LCFeCr Alloys in Liquid Iron

“…It should be noted that the effect of the matrix on the inclusion composition was much smaller compared to the 2D method, which was verified in a previous paper. [26] In terms of the inclusions at the boundary between the diffusion zone and the ''inclusion-free'' zone, they had higher FeO content (~20 mass pct). This closely related to the interdiffusion of Fe in the diffusion zone where the Fe contents was higher at the diffusion zone/bulk Fe interface.…”