Quantitative assessment of non-metallic inclusions in steel using an image-analysing computer

Although the last few years have seen a rapid increase in instruments available for inclusions assessment, little has been done to show the technologist how to use these new and important tools in routine work, such as quality control in steelworks. The researches described in this thesis partly meets that need and discusses how one of these instruments (the Quantimet Image Analysing Computer) may be used effectively. Inclusions assessment under the light microscope is subject to various errors including instrumental, sampling and sample-preparation. Effective use of any microscopic technique for the determination of non-metallic inclusion contents of bulk materials is, therefore, inevitably bound up with these problems and it is the responsibility of the technologist to ensure that the above errors are controlled within the required limits. However, this demands a knowledge of not only the magnitude of errors likely to be encountered in practice, their causes and effects but also of the occurrence and distribution of non-metallic inclusions in bulk materials, such as a "micro-section", a billet or an ingot of steel. [Continues.]