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Item Determination Activation Energy of Friction Stir Welding(WRTYS, Kyiv, 2017) Vakulenko, Ihor O.; Plitchenko, SerhiiEN: According to the technology of friction stir welding (FSW) heating of the edges is equal to 0.85-0.9 from the melting temperature of metal (T). Increase in temperature is accompanied by increased degree of the metal stirring, which leads to ambiguous influence on the metal density and concentration of cavities at different distances from the welding joint. At the same time, the temperature gradient across the section of joint leads to a different speed of recrystallization processes development and forming of structural heterogeneity in metal edges. Thus, the relevant question is to determine the optimal scheme of metal edges heating during the implementation of FSW technology. Material for the study was alloy AMg5. For different ratio of rotation speed and pressure on operating tool there were obtained the conditions of superplastic state of alloy at the temperatures of heating at the level of 0.45-0.5 from T, which corresponds to the beginning of dynamic recrystallization development during FSW. At the same time, it was evaluated the energy of activation (EA) of FSW process. Using the analysis of the obtained results it was determined the fact that when reaching the same temperature of alloy heating the EA value of FSW process decreases with increasing the rotation frequency of the operating tool and decreasing the degree of its pressing to the edges of welding joint. On the basis of the above mentioned the development of FSW technology should be directed toward the use of high speed rotations of the operating tool and low levels of its pressing to the alloy edges.