Method of determining particle size distribution of fine particles contained in metallic material

Abstract

The invention provides a method of determining particle size distribution of fine particles contained in metallic material. The method comprises: a step in which fine particles contained in a metallic material to be examined are isolated by extraction with a solution using a means of extraction for fine-particle isolation; a step in which the fine particles isolated by extraction are dispersed ina solvent to prepare a dispersion and the dispersion is separated into fine-particle dispersions having respective size ranges with a field-flow fractionation device; and a step in which the fine-particle dispersions having respective size ranges are irradiated with a laser light to determine the absolute value of the size of the fine particles of each dispersion from the angle dependence of the resultant reflected-light intensity, and the number density of the fine particles is determined from the reflected-light intensity.

Description

technical field [0001] The present invention relates to a particle size measurement method of particles (precipitates and non-metallic inclusions) in metal materials by field flow separation (FFF: Field Flow Fractionation) method. Background technique [0002] In recent years, there has been an increasing demand for higher quality metal materials. Relatively large inclusions generated during the deoxidation process of steel are the cause of serious deterioration of steel quality. For example, alumina-based oxides cause various defects such as surface defects in thin steel sheets for automobiles, cracks in beverage can manufacturing, and wire breakage in wire drawing of wire products. Therefore, various efforts have been made to reduce the amount and size of such inclusions. [0003] On the other hand, various attempts have been made to further improve the quality of steel products by artificially increasing or decreasing the amount and size of fine precipitates. For examp...

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Problems solved by technology

[0011] However, since the assumptions in the methods described in Patent Document 2 and Non-Patent Document 2 are incorrect, it cannot be said that the accuracy is high

In other words, as long as the actual discharge trace with a diameter of several mm is observed, it is naturally assumed that "one pulse emits light from multiple inclusions (oxides)", and the above assumption is incorrect.

[0012] In addition, in these luminescence analysis methods, particles such as inclusions that contribute to luminescence are in principle larger than several μm, so as long as the particles are not such a size, it is impossible to perform pulse intensity with the solid solution components contained in the matrix. Compare

In other words, the luminescence analysis method cannot be applied to fine particles smaller than several μm, and accurate analysis cannot be performed.

[0013] In this way, it is very important to quickly and accurately quantitatively analyze the particle size, frequency, and composition of particles in metals in quality control of metal materials, but this quantitative analysis has not been possible with conventional technologies.

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