S. K. Vil’danov.
ABSTRACT
Samples of values of temperature of liquid metal in the process of continuous casting of steel are analyzed. The samples are formed from the values of the temperature of the liquid metal in the steel-pouring ladle measured by the thermocouple and the data from five successive measurements of the temperature of the liquid metal in the tundish. Measurements in the steel-pouring ladle were made after the stage of vacuumizing the steel, before feeding the metal for continuous casting. Temperature measurements in the tundish were carried out throughout the entire casting period, including all heats assigned to the series. A hypothesis has been put forward about the normal distribution of the set of metal temperature values both in the steel-pouring ladle and in the tundish. The hypothesis was tested using three goodness-of-fit tests: the chi-square χ2 test, the Kolmogorov λ test and the Shapiro-Wilk W test. It is shown that the hypothesis of the normal distribution of temperature values in the steel-pouring ladle does not contradict the experimental data for all three criteria of agreement, and can be accepted. The hypothesis of a normal temperature distribution during measurements in the tundish should be rejected as inconsistent with the experimental data, while all three goodness-of-fit criteria show the need to reject this hypothesis. The main factors leading to a deviation of the temperature distribution from the normal law are: increased metal cooling rate in the tundish, introduction of slag-forming and heat-insulating mixtures onto the metal surface. With an increase in the number of temperature measurements in the tundish, the absolute values of the statistics of the goodness-of-fit tests, although they remain above the critical limit (the Pearson and Kolmogorov criteria of agreement) and below (the Shapiro-Wilk test), the temperature distribution in the tundish tends to a normal distribution.
KEY WORDS:
population, sample, temperature, steel-pouring ladle, tundish, goodness-of-fit criteria, normal distribution, deviation from the normal distribution law.
DOI: 10.31857/S0235010621010096