| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for quantitatively analyzing alumina in steel which promptly and accurately measures the amount of alumina using a spark discharge type emission spectral analyzing method, even when a ratio between solid solution Al and alumina is not constant, and the content of the Al in an alumina form is a trace amount which is 50 mass ppm or less.SOLUTION: A method for quantitatively analyzing alumina in steel includes: performing a large number of times of spark discharges between a steel sample and a counter electrode in an inert gas atmosphere, and determining a light emission intensity ratio between aluminum and iron for each discharge pulse; then drawing a frequency distribution chart with a horizontal axis as the light emission intensity ratio of the discharge pulse and a vertical axis as the frequency, calculating the most frequent value of the light emission intensity ratio from the frequency distribution chart, and determining alumina fraction using a threshold value α determined based on the most frequent value and a standard deviation of the light emission intensity ratio smaller than the most frequent value as a reference; then arraying the obtained light emission intensity ratio for each of the discharge pulses in ascending order, regarding the light emission intensity ratio at a fixed position as a representative Al intensity ratio, and determining an alumina intensity ratio from the product of the obtained alumina fraction and the representative Al intensity ratio; and then calculating the amount of the alumina in the steel sample using the obtained alumina intensity ratio. |
