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The paper is devoted to the study of friction stir welded samples, in which the special high-speed steel tool has been broken during the process of their production. The thickness of the samples is equal to 35 mm. It has been observed that after the tool breakage, the pin section separated from the tool remains in the weld. Around the pin, there is the structure modified by the severe thermomechanical action, which made it possible to estimate the size of the material fragmentation zone in the area ahead of the tool. After the breakage, the tool fragment itself has been deformed by the remaining part of the tool, including the shoulders. It resulted in the layering of the upper part of the pin fragment and the crack propagation into the central part of the pin. Based on the data obtained, it was considered that the tool breakage was caused by the excessive axial force, which resulted in the high tangent loads in the area below the shoulders. [ABSTRACT FROM AUTHOR]

In this work the study of the friction stir welding process of 2 mm thick aluminum alloy AA2024 sheets cut along and across the rolling direction was carried out. The obtained results show that the rolling direction of AA2024 sheet workpieces has a significant effect on the selection of optimal welding modes. It is revealed that at welding across the rolling direction it is possible to achieve the highest values of the ultimate tensile strength in a rather wide range of modes. [ABSTRACT FROM AUTHOR]

In this paper, regularities of the friction stir welding process parameters influence on mechanical properties of welded joints of different thicknesses are investigated. Joints were produced using the same type of tools with a screw-shaped pin. The tests show different dependencies of the joint mechanical behavior on the welding parameters. 2-mm-thick samples are characterized by high values of the ultimate tensile strength and a small variation of those when changing parameters. 10-mm-thick samples are characterized by a lower ultimate tensile strength and a greater variation at changing process parameters. [ABSTRACT FROM AUTHOR]