St. Petersburg State Polytechnic University (St. Petersburg, Russia):

Karkhin V. A., Dr. Eng., Prof., “Welding and laser technology” Chair
Novikov E. V., Cand. Eng., Associate Prof., “Technology and research of materials” Chair
Khomich P. N., Cand. Eng., Associate Prof., “Welding and laser technology” Chair

Central Scientific and Researh Institute of Structural Materials “Prometey” (St. Petersburg, Russia):

Tsukanov V. V., Dr. Eng., Head of Laboratory

E-mail (common): favor15@yandex.ru

A mathematical model describing thermal conductivity of complex (multistage) furnace thermal cycle and various borderline conditions of heat exchange between the ingot and the furnace has been created. The developed mathematical model governing hydrogen diffusion in ingots accounts for the size of the ingot, non-isothermal conditions and austenite-pearlite transformations. The objective of hydrogen diffusion in inhomogeneous body is formulated with regard to its potential. The correlation between hydrogen concentration in the center of the ingot, the proportion of hydrogen remaining in the ingot, hydrogen concentration distribution in the ingot after anti-flaking heat treatment considering specified initial hydrogen distribution in the ingot is discussed. Two alternatives of anti-flaking treatment of cylindrical ingots with the diameter 1096 mm are compared: the actual (long-term) treatment, involving heating above the А_С1 temperature, and the suggested (reduced) treatment, involving heating below the А_С1 temperature with the absence of concomitant phase transformations. It has been shown that radial distribution of hydrogen concentration after the completion of the treatment in accordance with both variants remains virtually unchanged. Hydrogen concentration in the center of the ingot reaches the maximum, which is 57% of initial concentration, while 64% of the initial volume of hydrogen stays in the ingot.

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