Influence of isothermal holding of various duration at subcritical temperature on spacial distributions of main chemical elements in finally normalized X60, E36, ASTM A516-65 steels was investigated using SEM X-ray microanalysis. A quantitative characteristic of non-uniformity of the distributions was proposed based on results of statistical processing of the local concentrations measurements. It was revealed that the most uniform distributions for the most elements is achieved after the holding at 710±5оС during 1-2 hours for X60, ASTM A516-55 steels and 4 hours for E36 steel. The results obtained are in agreement with the changes in steels microstructure caused by the researched thermal processing.
