This study investigates the effect of tool pin eccentricity and welding speed on the grain structure, crystallographic texture, and mechanical properties of friction stir welded (FSWed) AA5754-H24. Three tool pin eccentricities of 0, 0.2, and 0.8 mm at different welding speeds ranging from 100 mm/min to 500 mm/min and a constant tool rotation rate of 600 rpm were investigated. High-resolution electron backscattering diffraction (EBSD) data were acquired from each weld’s center of the nugget zone (NG) and processed to analyze the grain structure and texture. In terms of mechanical properties, both hardness and tensile properties were investigated. The grain structure in the NG of the joints produced at 100 mm/min, 600 rpm, and different tool pin eccentricities showed significant grain refining due to dynamic recrystallization with average grain sizes of 18, 15, and 18 µm at 0, 0.2, and 0.8 mm pin eccentricities, respectively. Increasing the welding speed from 100 to 500 mm/min further reduced the average grain size of the NG zone to 12.4, 10, and 11 µm at 0, 0.2, and 0.8 mm eccentricity, respectively. The simple shear texture dominates the crystallographic texture with both $\overline{B}$/B texture component with the C component at their ideal positions after rotating the data to align the shear reference frame with the FSW reference frame in both the PFs and ODF sections. The tensile properties of the welded joints were slightly lower than the base material due to the hardness reduction in the weld zone. However, the ultimate tensile strength and the yield stress for all welded joints increased by increasing the friction stir welding (FSW) speed from 100 to 500 mm/min. Welding using the pin eccentricity of 0.2 mm resulted in the highest tensile strength; at a welding speed of 500 mm/min, it reached 97% of the base material strength. The hardness profile showed the typical W shape with a reduction in the hardness of the weld zone and a slight recovery of the hardness in the NG zone.

The present research investigates the impact of eccentric shoulder tools on the microstructure and mechanical properties of friction stir welded (FSWed) aluminum alloy AA6082-T6. Two tools, one with an eccentric shoulder and one with an aligned shoulder, were employed under identical welding parameters: a rotational speed of 600 rpm, travel speed of 250 mm/min, and tilt angles of 0° and 3°. The four FSWed joints produced were characterized using optical microscopy, tensile testing, and hardness testing. The weld nugget zone (WNZ) microstructure showed significant grain size reduction from 5.24 μm for the base material to 1.63 μm, using the eccentric shoulder tool at 0° tilting angle and 2.78 μm at 3° tilting angle. The aligned shoulder tool resulted in an average grain size of 2.79 μm at 0° tilting angle and 2.23 μm of 3° tilting angle. Thus, the eccentric shoulder tool with a tilt angle of 0° exhibited the smallest average grain size. The mechanical properties obtained are consistent with the microstructure, where the joint produced using the eccentric shoulder at a 0° tilting angle showed the highest tensile strength of 216.5 MPa (89.7% joint efficiency) and 7.71% elongation. In contrast, the aligned shoulder tool resulted in coarser grains and a lower mechanical performance. In addition, this joint exhibited the highest hardness recovery in WNZ. The current study implies that the eccentric shoulder tool can eliminate the need for a tilting angle during FSW, which is required in some applications.

This study investigated the effect of a hemispherical friction stir welding (FSW) tool on the heat generation and mechanical properties of dissimilar butt welded AA5083 and AA7075 alloys. FSW was performed on the dissimilar aluminum alloys AA5083-H111 and AA7075-T6 using welding speeds of 25, 50, and 75 mm/min. The tool rotation rate was kept constant at 500 rpm. An analytical model was developed to calculate heat generation and temperature distribution during the FSW process utilizing a hemispherical tool. The experimental results were compared to the calculated data. The latter confirms the accuracy of the analytical model, demonstrating a high degree of agreement. Sound FSW dissimilar joints were achieved at welding speeds of 50 and 25 mm/min. Meanwhile, joints created at a welding speed of 75 mm/min exhibited a tunnel-like defect, which can be attributed to the minimal heat generated at this particular welding speed. At a lower welding speed of 25 mm/min, a higher tensile strength of the dissimilar FSWed joints AA5083 and AA7075 was achieved with a joint efficiency of over 97%.

The current study uses three different pin eccentricities (e) and six different welding speeds to investigate the impact of pin eccentricity on friction stir welding (FSW) of AA5754-H24. To simulate and forecast the impact of (e) and welding speed on the mechanical properties of friction stir welded joints for (FSWed) AA5754-H24, an artificial neural network (ANN) model was developed. The input parameters for the model in this work are welding speed (WS) and tool pin eccentricity (e). The outputs of the developed ANN model include the mechanical properties of FSW AA5754-H24 (ultimate tensile strength, elongation, hardness of the thermomechanically affected zone (TMAZ), and hardness of the weld nugget zone (NG)). The ANN model yielded a satisfactory performance. The model has been used to predict the mechanical properties of the FSW AA5754 aluminum alloy as a function of TPE and WS with excellent reliability. Experimentally, the tensile strength is increased by increasing both the (e) and the speed, which was already captured from the ANN predictions. The R² values are higher than 0.97 for all the predictions, reflecting the output quality.

Bi-modal particles are used as reinforcements for Cu-matrix. Nano TiC and/or Al₂O₃ were mechanically mixed with Cu particles for 24 h. The Cu-TiC/Al₂O₃ composites were successfully produced using spark plasma sintering (SPS). To investigate the effect of TiC and Al₂O₃ nanoparticles on the microstructure and mechanical properties of Cu-TiC/Al₂O₃ nanocomposites, they were added, whether individually or combined, to the copper (Cu) matrix at 3, 6, and 9 wt.%. The results showed that titanium carbide was homogeneously distributed in the copper matrix, whereas alumina nanoparticles showed some agglomeration at Cu grain boundaries. The crystallite size exhibited a clear reduction as a reaction to the increase of the reinforcement ratio. Furthermore, increasing the TiC and Al₂O₃ nanoparticle content in the Cu-TiC/Al₂O₃ composites reduced the relative density from 95% for Cu-1.5 wt.% TiC and 1.5 wt.% Al₂O₃ to 89% for Cu-4.5 wt.% TiC and 4.5 wt.% Al₂O₃. Cu-9 wt.% TiC achieved a maximum compressive strength of 851.99 N/mm². Hardness values increased with increasing ceramic content.

In the present work, the friction stir welding is applied on a three aluminum alloys that are AA1050-H12, AA 5754-24 and AA 7075 to investigate the effect of weld pitch on the mechanical properties and peak temperature. The friction stir welding are performed at weld speeds of 100, 300, and 500 mm/min. In all cases, the applied rotation speed is 600 rpm. A variation in the mechanical behavior of the welded alloys is observed. The UTS increases with increasing the weld pitch for the strain hardening alloys AA 1050 and AA 5754. A dramatic decrease of UTS with increasing the weld pitch is predominant for AA 7075. A maximum joint efficiency (tensile percentage) of 94 % is attained for AA5754 at faster weld pitch of 0.83 mm/rev whereas the minimum joint efficiency of 61.4% is a share of AA 7075-T6 at slower weld pitch of 0.17 mm/rev. A different hardness profiles are obtained for the experienced alloys and different strengthening mechanisms are discussed for result explanation.