Investigation of microstructural and wear behavior of Al6061 surface composites fabricated by friction stir process using Taguchi approach

The surface composites of aluminum alloys have a higher scope of applications encountering surface interactions in the aerospace, automobile, and other industries compared to the base aluminum alloys. The friction stir process (FSP) is recently the preferred method to prepare aluminum-based surface composites due to its capability to produce improved physical properties and refined microstructure at the surface. The study examines the Al6061 alloy-based surface composite fabricated by FSP for their wear behavior and microstructure. In this study, the Al6061 alloy-based hybrid surface composites are prepared with varying weight% of copper and graphite microparticles mixture as reinforcement by FSP with two tools having unique pin profiles, i.e., threaded cylindrical and plain cylindrical. These prepared composites are investigated for the dry sliding wear test on a pin-on-disc test set-up. The experiments are designed using the L9 orthogonal array and analyzed by the Taguchi approach to obtain the influence of disc speed, load, and reinforcement weight% on wear rate. The significant parameters influencing the wear rate of the samples tested are obtained using ANOVA. Later the effects of the friction stir process and the wear tests on the microstructure of the workpieces are investigated using FE-SEM/EDS tests. It is concluded that the decrease in wear rate with the rise in reinforcement weight% (Cu + graphite) from 2% to 6%. The load has the maximum effect on the wear rate for the samples prepared by threaded cylindrical FSP tool pin profile, while reinforcement weight% affects significantly the wear rate of the samples prepared by FSP with plain cylindrical pin profile tool.

Effect of Pin Geometry and Orientation on Friction and Wear Behavior of Nickel-Coated EN8 Steel Pin and Al6061 Alloy Disc Pair

Most mechanical systems (in particular, gear transmission system) undergo relative motion which results in increased friction phenomenon (friction coefficient, stresses, and wear rate) and thereby results in loss of efficiency. Mechanical parts undergo relative motion in different geometry configurations and orientations that induce a different state of stress as a result of friction. Till date, attempts are being made to minimize the friction with full sphere pin geometry configuration. The present work focused to reduce the frictional and wear rate, and experiments are conducted with tribo-pairs. i.e., nickel-coated pin surface slide against Al6061 alloy disc. The friction studies are carried out at different loads and geometries of pin surfaces (sphere and hemisphere configured at different orientations such as full sphere and hemisphere configured at 0°, 45°, and 90°) to induce different stress states with reference to sliding directions. Change in the geometry of EN8 pin material and their orientation with reference to sliding direction resulted in a different state of stress. The resulting stress levels were examined under the scanning electron microscope, which revealed the mechanisms of adhesion, abrasion, and extrusion. At a lower magnitude of orientation and load, the extent of asperity breaking lessens and material removal from pin surface decreases. Abrasion wear mechanism was observed corresponding to full sphere configuration on Al 6061 disc, whereas adhesive wear mechanisms are seen with hemisphere pins. The amount of aluminum transfer on pin surface with a hemisphere pin is comparatively more than that of full sphere configuration. At a lower magnitude of state of stress, the mechanism of sliding was dominated by the adhesion effect. At a higher level of state of stress, the mechanism of sliding was dominated by abrasion and extrusion.

Microstructure, microhardness, and tensile properties of hot-rolled Al6061/TiB2/CeO2 hybrid composites

T1B2 and CeO2 particle-reinforced A16061 hybrid composites were manufactured using stir casting and hot rolling techniques. The base alloy and composites were hot-rolled at 500°C and a 50% reduction was achieved through 12 passes. The effect of varying TB2 and CeO2 particle additions on the microstructure and mechanical properties of the Al6061 matrix was studied. Scanning electron microscopy showed uniform dispersion of both the reinforcements, with good interfacial bonding. Microhardness and tensile properties like yield and tensile strength were found to be higher for hybrid composite with 2.5% TiB2 and 2.5% CeO2 compared to Al6061 alloy and other hybrid composites. The increased tensile strength is attributed to good dispersion and interfacial bonding between the particles and Al6061 matrix. Fracture analysis using a scanning electron microscope revealed ductile fracture for the Al6061 alloy and mixed characteristics of ductile-brittle fracture for hybrid composites.

Investigation of the Tribological Characteristics of Aluminum 6061-Reinforced Titanium Carbide Metal Matrix Composites

The current trend in the materials engineering sector is to develop newer materials that can replace the existing materials in various engineering sectors in order to be more and more efficient. Therefore, the present research work is aimed at fabricating and determining the physical, mechanical, and dry sliding wear properties of titanium carbide (TiC)-reinforced aluminum alloy (Al6061) metal matrix composites (MMCs). For the study, the Al6061-TiC microparticle-reinforced composites were fabricated via the liquid metallurgy route through the stir casting method, where the reinforcement of the TiC particles into the Al6061 alloy matrix was added in the range of 0 to 8.0 wt.%, i.e., in the steps of 2.0 wt.%. The synthesis procedure followed the investigation of the various mechanical properties of Al6061-TiC MMCs, such as the density and structure, as well as mechanical and dry wear experimentation. The tests performed on the casted Al6061, as well as its TiC composites, were in harmony with ASTM standards. As per the experimental outcome, it can be confirmed that the increase in the weight percentage of TiC into the Al6061 alloy substantially increases the density, hardness, and tensile strength, at the expense of the percentage of elongation. In addition, the dry wear experiments, performed on a pin-on-disc tribometer, showed that the Al6061-TiC MMCs have superior wear-resistance properties, as compared to those of pure Al6061 alloy. Furthermore, optical micrograph (OM), powdered X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), and scanning electron microscopy (SEM) analyses were employed for the developed Al6061-TiC MMCs before and after the fracture and wear test studies. From the overall analysis of the results, it can be observed that the Al6061-TiC composite material with higher TiC reinforcement displays superior mechanical characteristics.

Mechanical characterization and fractography of 100 micron sized silicon carbide particles reinforced Al6061 alloy composites

In the current exploration, the impact of the 100 to 125 micron size addition of silicon carbide (SiC) on the mechanical performance of Al6061 alloy has been studied. The Al6061 alloy dispersed with 6, 9, and 12 wt.% of SiC particles were synthesized by a two-step stir cast route. Two-step addition of the preheated particles into the melt helps avoid the agglomeration of the particles, which further contributes to enhancing the properties of composites. The orchestrated composites were exposed to microstructural examines and mechanical properties evaluation. Microstructural portrayals of acquired examples were completed by SEM microscopy, EDS, and XRD patterns. The event of SiC particles were affirmed by the XRD patterns. The density of the Al6061-SiC composites was increased with the addition of high-density silicon carbide particles. The hardness, ultimate, and yield qualities of metal composites have been improved with the increase in the content of SiC support. The ductility of SiC reinforced composites decreased with hard ceramic particles' incorporation in the Al matrix alloy. Various fracture mechanisms were observed in the Al6061-SiC composites using SEM.

Study the effects of Process Parameters on Overcut of Al6061 Alloy by (Fe2O3) Nano- Powder-Mixed Micro-EDM

The effect of process parameters on micro-EDM namely current (I), voltage (V) and pulse on time (TON) were studied based on Tool Overcut (OC). The effect of Fe2O3 nano-powder mixed dielectric on the overcut for AL6061 alloy was studied using a Die Sinking (EDM) Machine. Effect of the process parameters was examined by 2-Level Factorial Design using Design of Experiment (DOE) software, whereas the level of importance was statistically evaluated using ANOVA. The results indicate discharge current and pulse on time significantly influenced the EDM process compared to voltage. It was also concluded that the use of Fe2O3 nano-powder mixed micro-EDM decreased the overcut values.