THE INFLUENCE OF PROCESS PARAMETERS ON THE MECHANICAL PROPERTIES OF FRICTION-STIR-WELDED JOINTS OF 2024 T351 ALUMINUM ALLOYS

摘要

The aim of this paper is to analyze the influence of the dominant parameters of Friction Stir Welding (FSW) on the mechanical properties of welded joints. Experimental investigations were carried out on 6-mm-thick plates made of the aluminum alloy AA 2024 T351. The rotation speed of the FSW tool was a constant 750 min', and the welding speed was (73, 116 and 150) mm/min. The obtained welds were free of imperfections and with an acceptable flat front surface. The testing of the mechanical properties of the FSW welded joint concerned the Vickers hardness test, tensile testing, bending tests, and Sharpy pendulum impact tests. The profile of the hardness distribution across the welded joint is made along three horizontal directions: near the face, in the middle and near the root of the weld. For the Sharpy impact testing, an instrumented pendulum Amsler RPK 300 was used. The FSW process generates three different microstructural zones: the nugget zone (NZ), the thermomechanically affected zone (TMAZ), and the heat-affected zone (HAZ), which were examined by optical microscopy and scanning electron microscopy (SEM). All the results of the experimental research indicated that the welding parameters n = 750 min(-1) and v = 116 mm/min give welded joints with the best mechanical properties.