A novel method for determination of semi-macro and macro size distributions of inclusions in steel from samples in ladle, tundish and mould has been developed. The samples are worked and surface treated before inspection. Mainly immersed ultrasonic scanning is performed to determine the semi-macro and macro inclusion content. The LSHR method has been tested in several different steel plants and for different steel grades. It is concluded that new information regarding large inclusions during steelmaking can be obtained using the method.

The LSHR sampler is a new development for providing a sample volume large enough to study semi‐macro and macro inclusions in clean steel. During the development of the LSHR sampler it was found that the pin where the steel enters the sampler can be used for the determination of the total oxygen content. Therefore, samples were taken at several different steel plants both in the ladle and the tundish as well as for the following five different steel grades: bearing steel, stainless steel 304L and 316L, DWI steel and ULC steel. The general conclusion regarding the sampling is that it was successful for all conditions and steel grades studied. The sample pins were examined for total oxygen content using both the inert‐gas‐fusion method and the fractional‐gas‐analysis method. Thereafter, the standard deviations with respect to the total oxygen data were used as a measure of the samples reliability. The general conclusion regarding the total oxygen determinations is that they were accurate for the five steel grades studied and the conditions under which the sampling took place.

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