TRANSFORMATION OF STRUCTURE DURING FRICTION STIR WELDING

In comparison with low carbon steels, there is increased interest in the use of aluminium-based alloys as materials for the manufacture of welded structures rolling stock of railway transport. During friction stir welding aluminium-based alloy, against the background of the analysis structural transformations, issues of development hardening processes are considered. Under conditions of existence, a temperature gradient at zone of weld formation, shown degree approximation alloy to the conditions of superplastic flow and influence from presence particles of the second phase on grain size of matrix is estimated. Evaluation of the separate influence grain size of matrix and state of solid solution at total hardness of the weld showed dependence of their contributions on temperature of hot plastic deformation. As the temperature of plastic deformation of alloy at area of the weld increases, contribution to the total hardness from grain size increase and on state of the solid solution decreases.