Friction Stir Processed Aluminium Alloy Research Articles

Investigation of the Effects of Overlapping Passes on Friction Stir Processed Aluminum Alloy 5083

Investigation of the Effects of Overlapping Passes on Friction Stir Processed Aluminum Alloy 5083

Microstructure and micro-mechanical properties of friction stir processed Al 5086-based surface composite

The present research work investigates the microstructure and mechanical properties of friction stir processed aluminium alloy 5086 based surface composite at micro-level. Towards the fabrication of surface composite, graphene and silicon carbide nano-particulates were introduced as a reinforcing medium. The mechanical properties at the micro-level were evaluated via in-situ micro-pillar compression. Based on experimental data, it was found that friction stir processing introduced severe plastic deformation, together with uniform distribution of the constituents phases and ensure grain refinement (from 4.19 µm to 1.59 µm), compared to the bulk material. This microstructural development had a positive impact to increase the compressive strength of the friction stirred processed composite, up to 193.3 MPa, compared to 147.8 MPa to that of bulk material. In addition to that, the deformation of the material possesses ductile fracture with enhanced plasticity, due to the incorporation of nano-particulate graphene and silicon carbide.

Influence of reinforcing particles on microstructure and mechanical properties of friction stir processed aluminium alloy AA7075‐T651

AbstractThis paper emphasis the improvement of mechanical properties of AA7075‐T651 using friction stir processing through localized surface modification by adding nano boron carbide particles. The reinforcement techniques such as the groove and blind hole methods were used by changing reinforcements of nano boron carbide and a matrix of AA7075‐T651 surface composites volume percentages (2 %, 4 %, and 6 %) along with tool rotational speed and processing speeds. Optical microscopy, scanning electron microscope and x‐ray diffraction analysis were used to examine the particle dispersion for the surface composites and to correlate with the enhanced mechanical properties. Results revealed that high input parameters have given grain coarsening and precipitate agglomeration and low input parameters provide poor nugget metal consolidation and no vertical material flow. The L9 orthogonal Array designed and optimized the process parameters for enhancing the surface properties of processed samples. Mechanical properties like ultimate tensile strength, yield strength, hardness, percentage of elongation and impact strength were evaluated for the groove friction stir processing method and blind‐hole friction stir processing methods. From the results, it has been observed that the blind‐hole technique resulted in higher hardness and the homogenous dispersion of nano boron carbide particles in the stir zone than the groove method. Consequently, for blind‐hole friction stir processing, grey relational analysis (GRA) and particle swarm optimization (PSO) approaches were proposed to optimise process parameters. From the compared optimization results between grey relational analysis and particle swarm optimization, particle swarm optimization approach was shown the best optimization results. Successively, the optimum condition in the respective experimentation is accomplished. Based on these observation and results, final validation tests were carried by changing the volume percentages of reinforcement keeping tool rotation speed and tool processing speed as constant. It is apparent that dynamic recrystallization in aluminium alloy at the processed zone due to presence of heterogeneous nucleation sites with nano boron carbide particles.

An Optimized Multilayer Perceptrons Model Using Grey Wolf Optimizer to Predict Mechanical and Microstructural Properties of Friction Stir Processed Aluminum Alloy Reinforced by Nanoparticles

In the current investigation, AA2024 aluminum alloy is reinforced by alumina nanoparticles using a friction stir process (FSP) with multiple passes. The mechanical properties and microstructure observation are conducted experimentally using tensile, microhardness, and microscopy analysis methods. The impacts of the process parameters on the output responses, such as mechanical properties and microstructure grain refinement, were investigated. The effect of multiple FSP passes on the grain refinement, and various mechanical properties are evaluated, then the results are conducted to train a hybrid artificial intelligence predictive model. The model consists of a multilayer perceptrons optimized by a grey wolf optimizer to predict mechanical and microstructural properties of friction stir processed aluminum alloy reinforced by alumina nanoparticles. The inputs of the model were rotational speed, linear processing speed, and number of passes; while the outputs were grain size, aspect ratio, microhardness, and ultimate tensile strength. The prediction accuracy of the developed hybrid model was compared with that of standalone multilayer perceptrons model using different error measures. The developed hybrid model shows a higher accuracy compared with the standalone model.

Mechanical, metallurgical and tribological properties of friction stir processed aluminium alloy 6061 hybrid surface composites

Friction stir processing (FSP) was applied in the fabrication of aluminium hybrid surface composites by embedding reinforcement particles namely, aluminium oxide (Al2O3), boron nitride (BN) and Graphite (Gr) with Boron carbide (B4C) in an equal volume basis. Three FSPed plates were fabricated at constant tool rotational speed of 1000 rpm, welding speed of 30 mm min−1 and axial force of 6 kN. The microstructure showed the homogeneous dispersion of reinforcement particles and good interfacial bonding between the reinforcement particles and the base material was observed in the processed zone. In terms of strength and hardness, surface composites with B4C and Al2O3 combinations yielded better mechanical properties over other the combinations. The results of wear studies reveal that the FSPed surfaces exhibited better resistance to wear when compared to the base material in a dry sliding condition. The dominance of abrasive wear was observed in all cases of the surface composites inspite of few micro cracks and delamination found on the worn surface. XRD analysis suggests that no secondary phases or intermetallic was formed anywhere in the processed zone.

Effects of tool pin profile on the formation of friction stir processing zone in AA1100 aluminium alloy

In the current investigation the effect of tool pin profiles (threaded cylindrical and straight cylindrical) on the mechanical properties (ultimate tensile strength, percentage elongation and joint efficiency) of friction stir welded and friction stir processed aluminium alloy (AA1100) was investigated. Taguchi L-18 array was used to select the transverse and rotational speed of the tool. The three distinct variables (tool shape, speed and feed rate) were used during investigation. From the results it was found that the joint fabricated by threaded tool profile gives maximum tensile strength and percentage elongation than the straight cylindrical tool pin profile. It is also found that, the threaded tool pin have good joint efficiency as compared to cylindrical tool i.e. maximum of 90% at 1800 rpm and feed rate of 50 mm/min. The joint constructed by threaded tool have maximum percentage elongation (8.38%) at 2400 rpm and feed rate of 45 mm/min. In addition, the joints fabricated by threaded tool pin profile have exhibited more ductility than cylindrical tool profile.

Soft computing model for predicting the wear resistance of friction stir processed aluminum alloy AA5083

In this study, AA5083 plates were friction stir processed to improve the hardness by refining the grains and dispersing the β phase in the matrix. Tool rotation speed, tool traverse speed, and tool shoulder diameter were varied as per the face-centered central composite design and FSP trials were performed. The wear resistance of the friction stir processed specimens was estimated by conducting a wear test using a pin-on-disc tribometer. It was observed that the wear resistance was higher than the base specimens and TRS, TTS and SD had a significant effect on the wear resistance. An artificial neural network model and a fuzzy logic model were developed to predict the wear resistance of the friction stir processed specimens. As the Sugeno Fuzzy model had greater prediction efficiency than the ANN model, it was used to study the effect of FSP process parameters on the wear resistance of the specimens. The results indicate that a TRS of 1000 rpm, TTS of 30 mm/min, and SD of 18 mm maximized the wear resistance of the processed plate to 8820 N-m/kg.

Investigating the effects of process parameters on the mechanical integrity of friction stir processed aluminium alloy

Abstract This article studies the effect of process parameters on the mechanical properties and corrosion behaviour of friction stir processed aluminium alloy. The parameters of friction stir processing (FSP) for 1100 Al alloys were studied at two different tool rotational speeds (600 and 1200 rpm) and two different passes (i.e., 1 and 3 passes). The study shows that 3-passes sample at 1200 rpm exhibit the least corrosion rate which is about 25% compared to the base material, while the tensile strength of the processed sample increased by 14%.

Effect of heat treatment on the mechanical and wear behavior of friction stir processed AA5052 alloy

Abstract Aluminium alloy AA5052 has excellent strength to weight ratio, which makes it best suited for marine applications. The study explores the effect of heat treatment on the mechanical, corrosion and tribological properties of friction stir processed aluminium alloy AA5052. The micro hardness, tensile strength and wear rate of the base material, friction stir processed and the annealed specimens were analyzed. The results indicate that the FSP followed by annealing increases hardness, tensile strength and resistance to wear of AA5052 alloy

Mechanism of Fracture in Friction Stir Processed Aluminium Alloy

Aluminium alloys are used for important applications in reducing the weight of the component and structure particularly associated with transport, marine, and aerospace fields. Grain refinement by scandium (Sc) addition can eliminate the casting defects and increase the resistance to hot tearing for high strength aluminium alloys. FSP for cast aluminium alloys have been focused and it has great advantages including solid state microstructural evolution, altering mechanical properties by optimizing process parameters. These parameters are tool rotational speeds (720, and 1000 rpm), traverse speeds (80, and 70 mm/min), and axial compressive force at 15 kN, etc. The mechanical properties had been evaluated on FSPed aluminium alloy with different microstructural conditions. Fracture properties of aluminium alloys are very important for industrial applications. Tensile and fracture toughness properties were correlated to microstructural and fractographic features of the aluminium alloys need to explore their essential failure mechanisms.

Effect of Friction Stir Processing on Gas Tungsten Arc-Welded and Friction Stir-Welded 5083-H111 Aluminium Alloy Joints

This paper presents the analysis of the friction stir-processed aluminium alloy 5083-H111 gas tungsten arc-welded and friction stir-welded joints. The comparative analysis was performed on the processed and unprocessed gas tungsten arc-welded and friction stir-welded joints of similar aluminium alloy 5083-H111. The results showed a clear distinction between the friction stir processed joints and unprocessed joints. There is a good correlation observed between the microstructural results and the tensile results. Ultrafine grain sizes of 4.62 μm and 7.177 μm were observed on the microstructure of the friction stir-processed friction stir-welded and gas tungsten arc-welded joints. The ultimate tensile strength for friction stir-welded and gas tungsten arc-welded before friction stir processing was 153.75 and 262.083 MPa, respectively. The ultimate tensile strength for friction stir processed friction stir-welded joint was 303.153 MPa and gas tungsten arc-welded joints one was 249.917 MPa. The microhardness values for the unprocessed friction stir-welded and gas tungsten arc-welded joints were both approximately 87 HV, while those of the friction stir-processed ones were 86.5 and 86 HV, respectively. The application of friction stir processing transformed the gas tungsten arc morphology from brittle to ductile dimples and reduced the ductile dimple size of the unprocessed friction stir-welded joints from the range of 4.90–38.33 μm to 3.35–15.59 μm.

Friction and wear measurements of friction stir processed aluminium alloy 6082/CaCO3 composite

The present study reports the friction and wear measurements of AA6082/CaCO3 composite fabricated using Friction Stir Processing (FSP). There is an improvement in the microstructure (grain refinement) for the FSPed AA6082/CaCO3 composite (10–12 µm) due to the dynamic recrystallization, which is evidenced using the optical microscope and X-Ray Diffraction analysis. Coefficient of Friction (CoF) and wear rate of the aluminium composites are mostly influenced by applied load. Hence, the tribological study is carried out for the samples at different applied loads from 2.5 N to 15 N using the pin-on-disc tribometer as per the ASTM G99-06 and the results are statistically validated using Design of Experiments. The addition of CaCO3 has improved the wear resistance of FSPed AA6082/CaCO3 composite about 2 times compared to FSPed AA6082. The worn surfaces are examined using Scanning Electron Microscopy (SEM) and the wear mechanisms experienced during the friction and wear measurements are discussed elaborately.

Microstructure, Hardness and Impact Toughness of Heat-Treated Nanodispersed Surface and Friction Stir-Processed Aluminum Alloy AA7075

Friction stir processing (FSP) is a recent surface engineering processing technique that is gaining wide recognition for manufacturing nanodispersed surface composites, which are of high specific strength, hardness and resistance to wear and corrosion. Herein, four-pass FSP was applied on aluminum alloy 7075 (AA7075-O) with and without the addition of alumina nanoparticles (Al2O3) of average size ~40 nm. All FSP parameters were constant at 40 mm/min transverse speed, 500 rpm and tilt angle of 3°. FSP rotation direction was reversed every other pass. The friction stir-processed materials were sectioned and solution treated at 515 °C for 1.5 h, followed by age hardening at 120 °C for 12, 24, 36, 48 and 60 h. The effect of heat treatment regimes on microstructure, hardness and toughness was examined, as well as the fracture mode. The new friction stir-processed surfaces without and with nanodispersion showed enhancement in the hardness of the surface of the AA7075-O material (65 HV) to almost a double (100 and 140 HV) after four-pass FSP (before heat treatment) without and with incorporating nanoalumina particles, respectively. After 48-h aging at 120 °C, a significant enhancement in impact toughness was achieved for both the friction stir-processed without and with nanodispersion (181 and 134 J, respectively), compared to the reference material AA7075 in T6 condition (104 J).

Effect of Under Surface Cooling on Tensile Strength of Friction Stir Processed Aluminium Alloy 6082

Friction stir welding (FSW) is a new upgraded version of friction welding. This technology is used worldwide especially in automobile and aerospace industries due to some of its advantages over conventional fusion welding techniques. Friction stir processing (FSP) has recently emerged as a new technique for microstructural surface modification of various materials or for changing the properties of metal by producing intense localized plastic deformation in the material. Friction stir processing is proved to be a viable tool for improving the mechanical properties of materials. This technique works on the principles of FSW. The plastic deformation is produced by same way as in FSW by inserting a non-consumable shouldered pin tool in the work piece and by providing lateral movement to the tool. FSP also used as a method for depositing materials like tool steels, stainless steels and hard facings materials to improve the quality of an underlying metallic base material. Simultaneous cooling of the specimen during FSP is a new approach to further improve the microstructural properties.The results of tensile testing show that the tensile strength can be improved with simultaneous under-surface cooling in FSP.

Analysis of the strain behaviour of a friction stir processed superplastic aluminium alloy

Superplastic forming is a well-established process by which very large, very complex shaped and also multi-sheets components can be manufactured in a single step. Combining this process with a suitable joining technique is of great industrial interest. In this work the strain behaviour of a friction stir processed aluminium alloy was investigated through free inflation tests. Principal parameters of the friction stir process were changed and free inflation tests were performed to assess the formability of the processed sheet. A strong influence of the friction stir process parameters was recorded on the formability of the processed material. Only a specified set of parameters assured a strain behaviour close to the one of the base material.

Microstructure characterization of the stir zone of submerged friction stir processed aluminum alloy 2219

Abstract Aluminum alloy 2219-T6 was friction stir processed using a novel submerged processing technique to facilitate cooling. Processing was conducted at a constant tool traverse speed of 200 mm/min and spindle rotation speeds in the range from 600 to 800 rpm. The microstructural characteristics of the base metal and processed zone, including grain structure and precipitation behavior, were studied using optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Microhardness maps were constructed on polished cross sections of as-processed samples. The effect of tool rotation speed on the microstructure and hardness of the stir zone was investigated. The average grain size of the stir zone was much smaller than that of the base metal, but the hardness was also lower due to the formation of equilibrium θ precipitates from the base metal θ′ precipitates. Stir zone hardness was found to decrease with increasing rotation speed (heat input). The effect of processing conditions on strength (hardness) was rationalized based on the competition between grain refinement strengthening and softening due to precipitate overaging.

Effect of microstructural inhomogeneity on superplastic behaviour of multipass friction stir processed aluminium alloy

Microstructures required for superplasticity were fabricated by intermittent multipass friction stir processing (FSP) in a 6mm 5086 aluminium alloy plate. Two processing parameters corresponding to two different heat inputs were used. Multipass FSP created a gradient microstructure with fine and coarse grain-depth features on the processed plates. Three sheets of 1.5mm thickness with different microstructural features were extracted for deformation testing under superplastic conditions: a layer with only fine grains from the nugget layer (NL), a layer with a thermomechanical-/heat-affected layer containing coarse grains (TL), and a composite layer (CL) having both fine and coarse grains in equal proportions. High temperature tensile testing was conducted for different layers between 450–550°C with strain rates ranging from 5×10−4s−1 to 1×10−2s−1 to determine the optimum superplastic conditions. The NL and CL were comparable in terms of ductility with a high m value of 0.44. The maximum ductility values were 325% for NL, 355% for CL and 230% for TL. The high ductility of the composite layers, despite their microstructural inhomogeneity, establishes multipass FSP as an effective bulk processing technique.

Biaxial Stressing of Sheets of Friction Stir Processed Aluminum Alloy A319

Cast Aluminum alloy A319 was multiple friction stir processed (5 single passes) to obtain a somewhat refined, equi-axed microstructure in which the size of the second phase particles had also decreased. The processed sheets, which had greater formability than the as-cast material, were subjected to different gas pressures and forming temperatures in an attempt to form a hemispherical dome. But the sheets failed before the hemispherical shape could be attained. The results of the forming experiments, which indicate extended plasticity, and the corresponding microstructures are discussed.

Fatigue crack growth behavior of friction stir processed aluminum alloy

The effect of friction stir processing (FSP) on fatigue crack growth (FCG) behavior of a cast aluminum alloy was examined. FSP leads to changes in silicon particle morphology and distribution. The fatigue properties of this alloy are influenced by silicon particle size and dendrite arm spacing. FCG experiments were performed in the Paris region to study crack growth rates during casting and FSP. Crack path and interaction of the crack-tip with the microstructure was characterized.