Study of Structural Phase Transformations in the Metal of Welded Joints of Reactor Plants for Nuclear Icebreakers

—The method of mathematical modeling was used to determine the rate of cooling of the heat-affected zone upon assembling the weld joints of reactor plants for nuclear icebreakers by preweld depositions. The effect of thermal cycles in various sections of deposited metal welded using three types of welding consumables, namely, carbon steel, silicon-manganese steel, and steel alloyed with nickel, was simulated using a quenching deformation dilatometer. The structure and hardness of the samples after simulated exposure to thermal welding cycles were studied. The deposited metal in using a Sv-06AA carbon wire was found to have a ferrite-pearlite structure throughout the range of cooling rates. An Sv-08GS manganese silicon wire forms an acicular ferrite structure in a wide range of cooling rates, while an Sv-10GN steel wire alloyed with nickel forms an acicular and quasi-polygonal ferrite structure.