Alloy AA Research Articles

Comparison of single action die and floating die for compaction of aluminum alloy AA7075 using simulation and experimental study

Compaction in powder metallurgy is considered to be one of the most critical steps in achieving the desired properties of green (before sintering) and final (after sintering) compacts that further play a very important role in final products manufactured using powder metallurgy. In this work, compaction was carried out using a single-action die and floating die (necessary pressure is applied from either the upper or lower punch). Simulations have been conducted with considering various loading conditions (20 to 200 kN) and friction coefficient (0 to 0.5 in the steps of 0.1) using both types of dies for manufacturing compacts of Aluminum alloy AA7075 as its demand in aerospace applications has been increased drastically in recent times. It was found from the simulated results that, to ensure satisfactory compaction using a single action die, the compaction load must be ≥100 kN, and the friction coefficient < 0.3. While, for a floating die, load ≥50 kN, and friction coefficient as zero. It was also found, that a single action die is not advisable to manufacture compact of especially Aluminum alloy AA7075 with a high aspect ratio (H/d > 1.5) in comparison with a floating die. It was also validated by experimental results. It was also observed that floating die compaction results in homogeneous physical, and mechanical properties as well as better microstructure. The compressive strength of the sintered compact is observed to be as high as 60% greater for the floating die compared to the single-action die. Moreover, it was improved by 94.14% compared to previous studies. Additionally, it was found that the effectiveness of the floating pressing die lies in its ability to achieve compaction without the complexity of a double-action system, offering practical implications for optimizing powder metallurgy processes and reducing costs.

Modeling the concurrent growth of inter- and intragranular Si precipitates during slow cooling of the alloy AA6016

Modeling the concurrent growth of inter- and intragranular Si precipitates during slow cooling of the alloy AA6016

Effect of double-pass friction stir welding and base materials position on the microstructural and mechanical behaviors of the dissimilar aluminum welded joints of AA6061 and AA2017

Friction stir welding (FSW) is a method of joining solid materials, where the parent metal’s melting temperature is below the point of amalgamation. FSW is a successful method for combining various ferrous and non-ferrous matrix materials. Many researchers’ studies suggested that FSW is suitable for both soft and high melting-point materials by changing the conditional attributes. A defect-free dissimilar weld joint of the alloys AA2017 and AA6061 was fabricated for the current investigation, and the effect of multi-pass friction stir welding (MPFSW) on the development of mechanical and different microstructural behaviors has been investigated. Welding conditions were a constant 1600 rpm weld tool rotational speed, a transverse speed is 32 mm min−1, and a tilt angle of 0°. As a consequence of the pinning effect, the results showed that increasing the number of welding passes in FSW from single to double improved the particle dispersion, which in turn improved the tensile strength, and micro-hardness of the FSWed joint. The primary objectives of this study investigate the strength that was improved because of the rise in the number of passes as well as the effective bonding of the materials’ weld interface, which gives tailor-welded blanks (TWBs) a considerably stronger joint. The findings revealed that the TWB joints’ metallurgical and mechanical properties are extremely varied from single-pass to double-pass, and the position of the base materials can significantly affect the joint properties that are produced.

Effect of tools rotational speed on the mechanical properties of one-step double-acting friction stir welded aluminum alloy AA 6061 hollow panel

The utilization of Aluminum hollow panels enhances structural strength while simultaneously ensuring a lightweight and efficient use of materials. During their application, these panels necessitate a welding process that is susceptible to porosity due to the disparity in hydrogen gas solubility between liquid and solid aluminum. Solid-state welding techniques, such as Friction Stir Welding (FSW), have proven to be effective and appropriate solutions for overcoming this issue. However, due to the thickness of the hollow panels, FSW process is unfeasible as it requires welding on both sides, resulting in prolonged production times. Consequently, the development of a one-step double-acting FSW technique becomes necessary, involving the simultaneous utilization of two tools. The usage of two tools introduces two sources of friction-stir forces, heat, and axial forces, demanding an assessment of the novel response from the specimens. This research aims to analyze the effect of a specific parameter, namely the tool rotation speed, within the one-step double-acting FSW process on the physical and mechanical properties of the AA6061 hollow panels. The One-Step Double-Acting FSW process involved conducting variations in the tool rotation speed on both sides of the welds. Specifically, for the 4G weld position (underside of the workpiece with an overhead weld position), speeds of 1200, 1500, and 1800 rpm were employed. Meanwhile, a consistent rotation speed of 1500 rpm was maintained for the 1G weld position (overside of the material with a flat weld position). The transverse speed and tilt angle are set at 30 mm/min and 2°, respectively. Elevating the tool rotation speed results in increased hardness, load capacity, and bending strength of the weld joints. The specimen subjected to the highest rotational speed (1800 rpm) exhibits the most exceptional mechanical properties, including a hardness of 73.46 HVN, load capacity of 18.47 kN, and bending strength of 60.56 MPa.

Investigation on the metallurgical and welding characteristics of AA7075/Fly ash composites

This study reinforces aluminium alloy AA7075 with industrial byproduct fly ash (FA) to improve the material's metallurgical and tribological qualities. Variable amounts of fly ash were included into a high-temperature vacuum stir casting process to create metal matrix composites (viz. 0, 6, and 12 wt%). From 60 BHN (AA7075) to 80 BHN (for 12 wt% FA), the hardness of the reinforced Al alloy was pointedly increased. Although there was only a little shift in values from 263 to 251 J for impact strength, this was in direct contrast to the upward trend shown in hardness. Different process factors, including FA concentration, sliding velocity, and applied load, were examined to see how the composites worn against an EN31 hardened steel disc. Extreme abrasive grooves and brittle fracture were observed at low levels of FA (between 0 and 6 wt%), whereas mild abrasive tracked by crumbling of the protective tribo-layer was observed at higher levels of fly ash (12 wt%). Taguchi design of trials was used to find the sweet spot between the several process parameters that would result in the least amount of sliding wear. Sliding at 1 m/s with an applied load of 20 N yielded the lowest wear rate for a composite with 12 % fly ash reinforcement.

Corrosion inhibitor screening for AA6014 aluminum alloy under different ambient conditions using a novel multielectrode methodology

A novel electrochemical cell to assess the effectiveness of organic corrosion inhibitors in preventing droplet corrosion for alloy AA6014. The study focuses on analysing the impact of pH and inhibitor chemical structure on their performance.

Study on Mechanical Behaviour of AA2014 Aluminium Alloy Blended with Cobalt (Co) and Iron Oxide (Fe2O3)

In order to increase system efficiency, lightweight materials are crucial in the automotive and aerospace sectors. In this work, iron oxide (Fe2O3) and cobalt (Co) were used as reinforcements, with aluminium alloy AA2014 serving as the matrix material. The metal matrix composites were made using the stir casting technique. The proportions of iron oxide and cobalt utilised as reinforcement in the composites were 2.5 wt % and 5 wt %, respectively. On the composite specimen created in accordance with ASTM E8, E9, and E23 standards, the mechanical properties of tensile, flexural, and impact strength were investigated. Investigations were also done on the hardness of the composites. The morphology of the composites was examined using an optical microscope.

Ultrasound-assisted material characterization: An innovative method for the non-destructive in-situ detection of microstructural changes of high-strength aluminum alloys

The use of aluminum alloys in conjunction with thermal-assisted forming techniques permits the production of high-strength and geometrically complicated components without failure. By using innovative, temperature-dependent production techniques, it is possible to manufacture components with tailored properties. So far, however, it is not possible to characterize the microstructural behavior under thermal and mechanical load in real-time. Using a novel characterization method, which is based on the principle of laser ultrasonic testing, it has become possible to record contact-free and non-destructive microstructural changes in-situ during thermo-mechanical treatment. This allows the interaction-free detection of thermal as well as mechanical effects during thermal-supported forming operations. In this research work, the temperature-dependent behavior during the quenching and aging process of the precipitation-hardenable aluminum alloy AA6082 for a tailor-quenched forming process is recorded in real-time using laser ultrasonic techniques. First, the effects of different tool temperatures on quenching rates and material properties were investigated using conventional characterization methods, including temperature measurement, hardness and tensile tests. It was shown that a die temperature of 325 °C leads to the lowest material hardness and strength. Subsequently, the results were compared with the novel, non-destructive in-situ testing method and validated using microstructural analysis. It was proven, that microstructural changes can be identified during varying quench and aging operations. Thus, the influence of different process parameters on the microstructural and mechanical development of aluminum components can be detected in-situ for the first time.

A study on residual stress measurement by DIC approach in FSW welded AA6082 joints

Aluminum Alloy is extensively used in aerospace and automotive industry due to its light weight and high strength properties. It is generally joined using Friction Stir Welding, which is a solid-state process. During this process residual stresses are developed in the welded region. It is a critical factor affecting the performance and lifespan of welded parts. Accurate measurement of residual stress is very important for ensuring the structural integrity of welded components. The conventional blind hole drilling method for residual stress estimation using the strain rosette, results error in the strain data capturing and compensating it is a challenging task. The omission of strain rosette is possible using the recently developed Digital Image Correlation in conjunction with Blind Hole Drilling. This paper focuses on the feasibility study of DIC in residual stress measurement. To accomplish this, Aluminum alloy AA6082 friction stir welded butt-joints are prepared. The residual stresses were measured at the top side of the weld joint using the DIC-BHD approach. At the weld top position, the transverse residual stress of -100 MPa approx. and the longitudinal residual stress of 118 MPa approx. were estimated.

The Impact of Friction Stir Process on Mechanical Properties of AA6082 Enhanced by Titanium Aluminum Carbide Ti3AlC2

This study investigates the effects of Friction Stir Processing (FSP) on the mechanical properties and microstructural refinement of aluminum alloy AA6082 and its composite reinforced with Titanium Aluminum Carbide (𝑇𝑖3𝐴𝑙𝐶2). The primary aim was to determine the extent to which FSP can enhance the compression strength and modify the microstructure of the base AA6082 and the AA6082/𝑇𝑖3𝐴𝑙𝐶2 metal matrix composite. Through a series of FSP treatments, we observed a microstructural refinement of 26% in the composite material. Concurrently, the compression strength of the materials processed by FSP demonstrated a significant increase of 16.3%. These results suggest that FSP is an effective method for enhancing the mechanical properties of AA6082, with implications for the material's application in industries where the strength-to-weight ratio is critical. This paper provides a detailed analysis of the microstructural transformation mechanisms and the corresponding enhancement in mechanical properties, offering insights into the potential of FSP in developing high-performance metal matrix composites.

Analysis of interfacial heat transfer coefficients in squeeze casting of AA6061 aluminum alloy with H13 steel die: Impact of section thickness on thermal behavior

A step die made of H13 steel was utilized in this investigation cast aluminum alloy AA6061 at a pressure of 95 MPa in sections measuring 3 mm, 6 mm, 9 mm, 12 mm, and 15 mm in thickness. Surface temperatures during the squeeze casting process, as well as temperatures at distances of 3 mm, 6 mm, and 9 mm from the inner wall of the die, were recorded using K-type thermocouples. Utilizing the inverse method to solve 1-D heat conduction equations, we successfully determined the interfacial heat transferring coefficients (IHTC) and the interfacial heat flux (IHF) of the cast and die surface. The calculations revealed that with the commencement of squeeze casting, there was a significant rise in the IHTC for each of the five sectional steps. These IHTC reached their peak before they began to decline. The peak range of IHTC incrementally increased with the section thickness, from the 3 mm of Step 1 up to the 15 mm of Step 5. Moreover, the rate at which the IHTC reached its peak and then stabilized at a low level was slower for steps with greater thicknesses.

Assessment on structural integrity of aluminium alloy AA6061 water tank used in satellite launch vehicles

AA 6061 is an age-hardenable aluminium alloy with 1wt% magnesium and 0.6wt% silicon as major alloying constituents and is used for manufacture of toroidal water tanks of earth storable liquid rocket engines of ISRO’s launch vehicles. These water tanks are used for storing water to generate steam in gas generator as well as for cooling various components of liquid rocket engine. As a part of the developmental efforts of a new source for fabrication of water tanks, a qualification test procedure was laid down, wherein a quarter portion of the water tank, namely the test article, is designed, fabricated and subjected to series of acceptance and qualification tests, including proof pressure test, cyclic pressure tests with intermediate non-destructive tests. These were finally followed by burst testing of the test article for conforming structural design margins and quality standards adopted for realizing the hardware. A burst test is a destructive test, performed to determine the overload capacity of the pressure vessels depicting margin of safety with respect to its mechanical strength limit. This work highlights the detailed manufacturing processes viz. forming, machining and welding including heat treatment of shells, metallurgical analysis carried out on the parent and weld specimens as well as results from proof pressure and pressure cyclic tests. Further, fractographic studies were carried out on the burst tested hardware, wherein specimens collected from different locations of the burst tested hardware were analyzed using optical scanning electron microscopy, to locate the origin of crack initiation and nature of the failure.

Processing understanding, mechanical durability and hygrothermal stability of PC/AA6061 hybrid joints produced via injection overmolding

In the present study, single-lap joints of polycarbonate (PC) and laser-textured aluminum alloy AA6061 were manufactured by injection overmolding (IOM) and characterized in terms of the microstructure, quasi-static and long-term mechanical performance and hygrothermal stability. The injection overmolding parameters were optimized through design of experiments and analysis of variance, which showed that the parameters of barrel temperature, injection speed and holding pressure positively affected the ultimate lap-shear force (ULSF). PC/AA6061 injection overmolded hybrid joints exhibited outstanding joining strength of 7.2 ± 0.5 MPa. Under fatigue cyclic loading, hybrid joints produced with optimized IOM processing conditions showed a fatigue life of 35 % ULSF at 106 cycles, demonstrating excellent mechanical durability. Moreover, PC/AA6061 injection overmolded hybrid joints showed good hygrothermal stability, with no significant variations in joining strength after aging in water at 80 °C for 30 days.

Optimization on the electrical discharge machining (EDM) process parameters of aged AA7075/TiC metal matrix composites

The need to optimize the process parameters in Electrical Discharge Machining (EDM) for aged AA7075 Metal Matrix Composites (AAMMCs) is evident as it impacts various aspects such as mechanical properties, tool wear, surface finish, integrity, precision, accuracy, process stability, process consistency, and cost-effectiveness. In this study, aluminium alloy AA7075 was chosen as the matrix material because of the need to enhance its mechanical properties. Titanium Carbide (TiC) was chosen as the reinforcing material owing to its superior mechanical properties. Therefore, TiC holds the capability to improve the mechanical attributes of AA7075. The selection of the stir cast method for the manufacturing of AA7075/TiC (0, 4, 8, 12, and 16 wt.%) was based on its ease of fabrication, ability to achieve a uniform distribution of reinforcements, reduced susceptibility to oxidation and porosity, and improved control over the microstructure. This AA7075/12wt.%TiC MMC underwent an aging process at 520 °C for 180 min and was subsequently cooled within the furnace environment. The density of the aged and non-aged AA7075/TiC-based composites was determined through a density test using the Archimedes’ principle. Microhardness testing was conducted on the non-aged and aged AA7075-based MMCs employing a Vickers microhardness tester. Tensile strength and compressive strength of the aged and non-aged AA7075-based MMCs were determined by the usage of a universal testing machine (UTM) and a compression testing machine (CTM). The optimal combination of the manufactured AA7075/TiC MMCs was determined based on their mechanical properties. The most effective combination was identified as AA7075/12wt.%TiC MMC due to its superior values in hardness, tensile strength, compressive strength, and density compared to other combinations. The aging process aimed to enhance the mechanical properties without the need for additional reinforcements. EDAX and X-ray Diffraction Analysis (XRD) tests were employed to determine the weight percentage of the matrix and reinforcements and to identify the formation of precipitates in the AA7075/12wt.%TiC composites. The SEM equipment was utilized to verify the uniform distribution of titanium carbide in the matrix material AA7075. Optimization of EDM process parameters for aged AA7075/12wt.%TiC composite was carried out using Taguchi design-based Grey Relational Analysis (GRA). The selected input parameters for the optimization included the chromium concentration (g×l-1), current (amps) and pulse-on time (µs). The response parameters chosen for optimization were surface roughness (SR) and tool wear rate (TWR). The sequence of influencing EDM input parameters is chromium concentration, pulse on time and current. The optimized EDM process parameters were 8 g×l-1 chromium concentration, 5 amps current and 240 µs pulse on time and the corresponding response were 0.198 TWR and 1.56 SR.

Rapid synthesis of organosilicon oxide thin films and post-curing for enhanced scratch and corrosion resistance of aluminum alloy

Organosilicon oxide (SiOxCy) film deposited onto flexible aluminum (Al) alloy AA1050 substrate by an atmospheric pressure plasma jet and combined with post-curing in air at 150–300 °C for 30 min, is investigated to highly improve the scratch and corrosion resistance of Al substrate from a presence scratching up to 6.4 % after first scratch test (against #0000 steel wool at 100 g loading) and a corrosion rate up to 3.73 mm/Yr after immersed for 12 h (against in PH2-3.5 wt% NaCl–HCl aqueous solution) for the original Al substrate to a thorough deficiency of scratching (0 %) up to 140 scratch tests and a corrosion rate up to 0.0066 mm/Yr for Al/SiOxCy. The enhanced scratch and corrosion resistance of Al/SiOxCy are proven to be greatly dependent on their film properties, and surface characteristics of nano SiOxCy films and post-cured in air at 150–300 °C.

Joining of Polymer to Aluminum Alloy AA1050 By Friction Spot Welding

The friction spot welding process is used to join the hybrid joint of aluminium to polymer. AA 1050 Aluminum alloy and polyethylene polymer (type of plastic) were used for joining. Aluminium surface treatment was done to increase the wettability of it. The surface treatment was done by electrochemical treatment. Two parameters of the joining process were used: (1, 1.5 and 2) min. (920, 1340 and 1500) rpm for time and rotational speed, respectively. Many tests for the joint are done: shear test and Scanning electron microscopy (SEM). Using the Minitab program, the effect of the parameters on the joint was analysed. The maximum value of the shear force was (1587 N) at 1.5 min. time and 1340 rpm rotational speed. The minimum shear force was (589 N) at 1 min. time and 920 rpm rotational speed. The joints which were tested failed by an interfacial shear with a ductile fracture of the polymer side. The process of joining mechanism occurred through a mechanical interlocking between the molten polymer and the surface of the AA 1050 aluminium specimen, cohesive and adhesive. The average thickness for the joint of the tested specimens was 4µm.

Effect of Copper/Alumina Hybrid Reinforcement on the Microstructure and Mechanical Properties of Stir Cast Aluminum Alloy AA6063

The present study investigated the microstructural characteristics and mechanical behavior of hybrid composites with an aluminum matrix reinforced with copper and alumina. To prepare these composites, copper and alumina were mixed in varied weight ratios and added to a 10 wt % hybrid reinforced Al-Mg-Si alloy using a two-step stir casting process. The resulting composites were characterized using hardness, tensile properties, and scanning electron microscopy. The findings reveal that composites with Al-90 %/Cu-7.5 %/ Al2O3-2.5 % and Al-90 %/Cu-5 %/ Al2O3-5 % exhibited the optimum mechanical properties, including hardness and tensile properties. The microstructure of all composites showed the presence of copper particles and Al2O3 reinforcement, which were distributed nearly uniformly throughout the metal matrix despite the presence of pores. The EDS profile of a representative composite showed peaks of aluminum (Al), copper (Cu), carbon (C), magnesium (Mg), silicon (Si), oxygen (O), manganese (Mn), and traces of calcium (Ca), sulfur (S), and potassium (K). Based on these results, further investigation could be conducted on the wear and corrosion properties of the aluminum alloy when reinforced with copper and alumina.

Optimizing joint structure and performance in friction spot joining of aluminum alloy AA6061 and poly-ether-ether-ketone (PEEK)

This study investigated the challenge of joining poly-ether-ether-ketone (PEEK) to aluminum alloy AA6061 through friction spot joining (FSpJ), by examining the impact of surface treatment of AA6061 sheets and analyzing various process parameters' effects on joint interface morphology, tensile-shear strength, and failure. Results indicated a peak interface temperature may reach 400 °C during FSpJ, with a 0.5–0.9 mm molten PEEK layer containing sealed bubbles. Notably, Boehmite treatment significantly improved joint strength, although the primary failure occurred in the PEEK base material. An optimization through response surface method (RSM) analysis identified plunging depth as the most influential factor in joint strength, and a peak load of 4576 N with an optimized combination of pin rotation speed, plunging depth, and dwell time was achieved. Using optimized process parameters, strong PEEK-AA6061 joints can be formed, and the approach is extendable to joining other metallic and polymeric materials.

Numerical and Experimental Analysis of the Forging of a Bimetallic Crosshead

Abstract The automobile sector has been making increasing efforts to reduce the weight of automobiles, aiming at mitigating pollutant gas emissions. The use of innovative concepts, such as bimetallic components, has become attractive because it makes it possible to increase the strength-to-weight ratio of the components. In this study, the hot forging of a bimetallic crosshead is investigated. In the process, a billet with a cylindrical core of the magnesium alloy AZ61 is enclosed with a hollow cylinder of the aluminum alloy AA 6351 and forged at 400°C. The objective is to reconcile the low density of Mg alloys with the high corrosion resistance of Al alloys. In parallel, a finite element analysis of the process was carried out.

A Comprehensive Investigation of BN and VC Reinforcements on the Properties of FSP AA6061 Composites

This present study investigated the impact of incorporating boron nitride (BN) and vanadium carbide (VC) reinforcements on various properties of friction stir processed (FSP) AA6061 alloy composites, focusing specifically on grain structure, thermal conductivity, electrical conductivity, and compressive strength. The findings indicate that VC more effectively refines the grain structure of the AA6061 alloy during FSP compared to BN. The inclusion of BN particles in the metal matrix composites resulted in a decrease in both thermal and electrical conductivity. In contrast, the addition of VC particles led to an increase in both thermal and electrical conductivity. The AA6061/VC composite material exhibited the highest thermal conductivity among all composites tested. The electrical conductivity of the hybrid-composite AA6061/30%BN+70%VC showed a slight reduction, measuring only 2.8% lower than the base alloy AA6061. The mono-composite AA6061/VC exhibited a marginal decrease in thermal conductivity, with a measured value only 7.5% lower than the conventional alloy AA6061. However, the mono-composite AA6061/BN displayed a more significant decline, exhibiting a loss of 14.7% and 13.9% in electrical and thermal conductivity, respectively. The composite material comprising 30% BN and 70% VC reinforcement demonstrated the highest compressive strength compared to all other tested composites. The observed percentage enhancement in the mechanical properties of mono and hybrid composites, compared to the parent AA6061 alloy, ranged from 17.1% to 31.5%.