Influence Of Tool Rotational Speed Research Articles

Wear and mechanical properties of 6061-T6 aluminum alloy surface hybrid composites [(SiC + Gr) and (SiC + Al2O3)] fabricated by friction stir processing

In this investigation, the influence of tool rotational speed on wear and mechanical properties of aluminum alloy based surface hybrid composites fabricated via Friction stir processing (FSP) was studied. The fabricated surface hybrid composites have been examined by optical microscope for dispersion of reinforcement particles. Microstructures of all the surface hybrid composites revealed that the reinforcement particles (SiC, Gr and Al2O3) are uniformly dispersed in the nugget zone. It was observed that the microhardness decreases when increasing the rotational speed and showed higher microhardness value in Al–SiC/Al2O3 surface hybrid composite due to presence and pining effect of hard SiC and Al2O3 particles. It was also observed that high wear resistance exhibited in the Al–SiC/Gr surface hybrid composites due to presence of SiC and Gr acted as load bearing elements and solid lubricant respectively. The observed wear and mechanical properties have been correlated with microstructures and worn micrographs.

Influence of tool rotation speed and feed rate on the forming limit of friction stir welded AA6061-T6 sheets

In this study, the influence of tool rotation speed and feed rate on the forming limit of friction stir welded Al 6061-T651 sheets has been investigated. The forming limit curve was evaluated by limit dome height test performed on all the friction stir welded sheets. The welding trials were conducted at a tool rotation speed of 1300 and 1400 r/min and feed rate of 90 and 100 mm/min. A third trial of welding was performed at a rotational speed of 1500 r/min and feed rate 120 mm/min. It is found that with increase in the tool rotation speed, from 1300 to 1400 r/min, for a constant feed rate, the forming limit of friction stir welded blank has improved and with increase in feed rate, from 90 to 100 mm/min, for a constant tool rotation speed, it has decreased. The forming limit of friction stir welded sheets is better than unwelded sheets. The thickness gradient after forming is severe in the cases of friction stir welded blanks made at higher feed rate and lower rotation speed. The strain hardening exponent of weld ( n) increases with increase in tool rotation speed and it decreases with increase in feed rate. It has been demonstrated that the change in the forming limit of friction stir welded sheets with respect to welding parameters is due to the thickness distribution severity and strain hardening exponent of the weld region during forming. There is not much variation in the dome height among the friction stir welded sheets tested. When compared with unwelded sheets, dome height of friction stir welded sheets is higher in near-plane-strain condition, but it is lesser in stretching strain paths.

Investigating effects of process parameters on microstructural and mechanical properties of Al5052/SiC metal matrix composite fabricated via friction stir processing

Friction stir processing (FSP) is a novel process for refinement of microstructure, improvement of material’s mechanical properties and production of surface layer composites. In this investigation via friction stir processing, metal matrix composite (MMC) was fabricated on surface of 5052 aluminum sheets by means of 5μm and 50nm SiC particles. Influence of tool rotational speed, traverse speed, number of FSP passes, shift of rotational direction between passes and particle size was studied on distribution of SiC particles in metal matrix, microstructure, microhardness and wear properties of specimens. Optimum of tool rotational and traverse speed for achieving desired powder dispersion in MMC was found. Results show that change of tool rotational direction between FSP passes, increase in number of passes and decrease of SiC particles size enhance hardness and wear properties.

Liquid film formation and cracking during friction stir welding

The influence of tool rotation speed and travel speed during friction stir welding is studied in the case of Al 2024 which contains low melting point phases. When a tool rotation speed of 1600 rev min−1 is applied with a travel speed of 100 mm min−1, S-phase (Al2CuMg) particles in the base material form melted films, promoting the formation of spalling defects comprising subsurface cracks along the trailing edge of the weld below the tool shoulder. Decreasing the tool rotation speed to 400 rev min−1 prevented formation of the melted films by reducing the peak temperature in the stir zone, and avoided formation of spalling defects. When the travel speed is decreased to 32 mm min−1 when using 1600 rev min−1, dissolution of the S-phase occurs and fewer melted films remain in the stir zone. This implies that travel speeds are limited in alloys which contain low melting point phases since these promote cracking defects.

Friction spot joining of an extruded Al–Mg–Si alloy

Friction spot joining was used to make lap joints on strips of an extruded Al–Mg–Si aluminium alloy. The influence of tool rotational speed, plunge rate and depth, and dwell time prior to tool retraction on the weld axial plunge force was monitored using high speed data acquisition. The effect of these parameters on bond formation and tensile shear strength of the resulting joints was determined. An optimum combination of parameters that maximises joint tensile shear strength was identified.

Production of Ultra-Fine Grained Aluminum Alloy using Friction Stir Process

1050 aluminum alloy with an ultra-fine grain size was produced through friction stir process (FSP). The influence of tool rotation speed on the temperature profile, microstructure and mechanical properties of the friction stir processed zone (FZ) was also experimentally investigated. FSP was carried out with only a single pass at tool rotation speeds ranging from 560 to 1840 min � 1 under a constant tool traverse speed of 155 mmmin � 1 . The maximum temperature of the FZ was lower than the melting point of the workpiece material, although increasing linearly with the tool rotation speed. The cooling rate of the FZ also increased linearly from 341 to 1473 � Cmin � 1 with the tool rotation speed. The FZ had very low dislocation density and was composed of fine equiaxed grains. These fine grains would result from the growth inhibition of dynamically recrystallized grains by the high cooling rate of the FZ. The grain size of the FZ increased with the tool rotation speed. However, it is noteworthy that, for 560 min � 1 , the grain size decreased to even the submicron level in spite of only the single pass of FPS. The average hardness of the FZ increased significantly for 560 min � 1 to about 37% as compared with the unprocessed zone (UZ), although decreasing with the increase in the tool rotation speed. For 560, 980 and 1350 min � 1 , the tensile test specimens were fractured in the UZ. This result indicates that the tensile strength of the FZ increased more than that of the UZ by the grain refinement through FSP. Hence, it is concluded that FSP is very effective in producing an ultra-fine grained material with excellent mechanical properties. In addition, it is possible to control its grain size resulting in the mechanical properties by varying the maximum temperature with the tool rotation speed.