Showing papers on "Friction stir processing published in 2023"

Developing ultrafine-grained structure with balanced α/γ fraction via underwater friction stir processing enables enhanced wear and corrosion resistance of duplex stainless steel

Abstract: Further improving the wear and corrosion resistance of duplex stainless steel (DSS) without disrupting the balanced ferrite (α)/austenite (γ) ratio is worth exploring, but very challenging. Here, we explored the feasibility of utilizing solid-state friction stir processing in air (AFSP) and underwater (UFSP) to realize surface modification of DSS. Notably, we successfully developed an ultrafine-grained (UFG) structure with balanced α/γ ratio on the DSS by UFSP, which imparts both enhanced wear and corrosion resistance to the sample surface. Further, the associated microstructure evolution mechanism during FSP of DSS in both environments is systematically elucidated. The simultaneous improvement in both wear and corrosion resistance is well correlated with the resulting microstructure characteristics. This work provides a simple and cost effective pathway to achieve a synergistic increase in the wear and corrosion resistance of DSS. We anticipate that the UFSP should be applicable to many dual-phase metallic systems.

Fabrication of new gradient AZ91-bioactive glass composite using friction stir back extrusion

Abstract: This study investigated the microstructure, mechanical characteristics, and in vitro corrosion behavior of gradient AZ91-bioactive glass composite wire fabricated by friction stir back extrusion. The results showed that by decreasing the extrusion speed from 40 to 20 mm/min, the distribution factor of bioactive glass increased from 0.31 ± 0.04–0.45 ± 0.07, and more homogenous grain size was formed at the surface and center zone of the composite wire. Under the influence of heat and plastic deformation during friction stir back extrusion, despite the formation of the β-phase in separate islands, the α + β eutectic phase was also formed in the composite wire. In composite wire processed with a rotational speed of 800 rpm and extrusion speed of 20 mm/min, a gradient distribution of bioactive glass was formed in the cross section of the wire. Compared to an as-cast AZ91 alloy, friction stir back extrusion conducted at a rotational speed of 800 rpm and an extrusion speed of 20 mm/min resulted in a 44% increase in corrosion resistance in simulated body fluid (SBF).

A review of Mg alloys containing long-period stacking ordered (LPSO) structures with insight into the application of friction stir processing

Abstract: Owing to their excellent mechanical/functional properties, the lightweight magnesium alloys containing long-period stacking ordered (LPSO) structures have recently received a great deal of attention. In the present overview article, the atomic structures, formation mechanisms, transformations of 18R and 14H phases, and morphology of LPSO phases in various Mg-based systems containing special rare earth elements (such as Y and Gd) and transition metal elements (such as Zn, Ni, and Cu) are reviewed. Then, the effects of thermomechanical processing and severe plastic deformation (SPD) techniques on the grain refinement of the α-Mg matrix by dynamic recrystallization (DRX), kinking as the main deformation mechanism of the LPSO phase, as well as the fragmentation and dispersion of LPSO phase are summarized. Afterward, the reported works on the application of friction stir processing (FSP) and friction stir welding (FSW) for the processing of LPSO-containing Mg alloys regarding the microstructural evolution, mechanical properties, and strengthening mechanisms are critically discussed. Finally, distinct suggestions for future works are proposed, including the investigation of the kinetics of the LPSO phase formation, fabricating by the emerging processing technologies such as additive manufacturing (AM), evaluating the FSP processing parameters (especially multi-pass FSP and applying the Zener-Hollomon parameter), characterizing the DRX mechanisms (such as discontinuous, continuous, and twinning-induced DRX, as well as the particle stimulated nucleation for texture weakening), and studying the superplasticity and superplastic forming of LPSO containing Mg alloys during hot deformation.

Microstructural characterization and mechanical properties of AlMg alloy fabricated by additive friction stir deposition

Abstract: This work investigates the microstructure characterization and mechanical properties of Al alloy fabricated by additive friction stir deposition (AFSD). Microstructure characterizations of the Al alloy 5B70 base material (BM) and build were compared using optical microscope (OM) and electron back scattered diffraction (EBSD). The hardness distribution in the direction perpendicular to the cross-section of the deposited area was systematically evaluated. Tensile tests were performed on the BM and the build using digital image correlation (DIC), and the real-time stress distribution states of the specimens were analyzed. After the tensile tests, the fracture micromorphology was characterized using scanning electron microscope (SEM). The results indicated that a high degree of recrystallization occurred in the deposition zone, where fine, equiaxed, and differently oriented grains are formed. It was found that the strength of the deposition layer was lower compared to that of the BM, but its toughness was significantly improved. Also, obvious anisotropy of mechanical properties was identified in the deposition layer.

An Investigation of the Mechanical, Thermal and Electrical Properties of an AA7075 Alloy Reinforced with Hybrid Ceramic Nanoparticles Using Friction Stir Processing

Abstract: Aluminum AA7075, graphene nanoplates (GNP), boron nitride (BN), and vanadium carbide (VC) are used to fabricate hybrid nanocomposite matrices. BN and VC serve as secondary reinforcement particles in the fabrication of hybrid composites, with graphene (GNP) as a key component of the hybrid process. Friction stir processing (FSP) was used to manufacture the composite matrix; it also has a major role in improving the microstructure’s grain refinement, as well as the reinforcing of the particles, which play a crucial role in limiting grain growth during the dynamic recrystallization process. Consequently, the grain sizes of the nanocomposite AA7075/GNPs, hybrid composites AA7075/GNPs+BN, and hybrid composites AA7075/GNPs+BN+VC were decreased by an average of 10.3 times compared to the base alloy. The SEM analysis demonstrated that the dispersion of the hybrid reinforcement particles was performed, and the particles were dispersed uniformly throughout the metal matrix. The mechanical characteristics of the hybrid AA7075/GNPs+BN+VC include the highest compression stress and hardness values due to the homogeneity of the hybridization process between the BN and VC particles. The GNPs reduce the electrical conductivity by 7.3% less than the base alloy. In comparison, when hybridized with BN and VC, it is reduced by 24.4% and 31.1%, respectively. In addition, the inclusion of thermally insulating materials, such as BN and VC, decreases the thermal conductivity of the hybrid composite metal matrices.

Impact of Hard and Soft Reinforcements on the Microstructure, Mechanical, and Physical Properties of the Surface Composite Matrix Manufactured by Friction Stir Processing

Abstract: This work studies the effect of incorporating a mix of reinforcement particles of a hard and soft nature on the microstructure and mechanical and physical properties of a high-strength aluminum alloy, AA7075. A friction stir processing technique was used for compositing the surface of this alloy. The vanadium carbide (VC) was selected to be the hard reinforcement, while the boron nitride (BN) and graphene nanoplates (GNPs) were chosen as soft reinforcements. Mono VC, hybrid reinforcements combined of 50 vol.% VC and 50 vol.% BN, and triple reinforcements combined of 33.4 vol.% VC, 33.3 vol.% BN, and 33.3 vol.% GNPs were used for producing the composites. Intensive grain refinement was observed, 930%, in the composite with triple reinforcements. The microhardness and the ultimate compressive strength were improved and reached b0, 29%, respectively, in composites that contained GNPs. The thermal properties were significantly improved, and the coefficients of thermal expansion (CTE) and thermal conductivity decreased to 88% and 15%, respectively. The composite’s electrical conductivity was decreased by 58% with triple reinforcements.

Recent trends in parametric influence and microstructural analysis of friction stir welding for polymer composites

Abstract: Over the past several years, friction stir welding (FSW) of polymers and their composites has received a lot of interest. In this respect, an effort has been made to explore the articles on current trends to gain a more in-depth understanding of friction stir welding of various polymers. There is an emphasis on fine-tuning the FSW processing settings to maximise the efficiency of the resulting joints. Besides this, the study highlights that the research community has applied the ANOVA to analyse the parametric effect of welding factors on each performance characteristic during the FSW of polymers. Friction stir welding leaves holes as a defect in the end stage, and this area needs more research and development. This review study also includes a summary of the researchers’ recommended tool setup, microstructure analysis, and other best practices.

Design and development of a new machine tool for continuous friction stir extrusion

Abstract: In the present paper the Continuous Friction Stir Extrusion process (CFSE), derived from the already known Friction Stir Extrusion (FSE), is proposed for effective solid-state recycling of metal scraps. A new dedicated machine tool was designed and developed. A Lagrangian implicit thermomechanical numerical model was set up and used to determine the proper ranges of the most relevant process parameters. An effective case study is proposed, involving the actual extrusion of a recycled wire in a continuous way. Metallurgical observations and mechanical characterization tests were carried out on the obtained specimen showing the potential of the process and its industrial feasibility.

Wear and corrosion behaviour of multiple pass friction stir processing on aluminium alloy 6061 embedding with B4C particles

Abstract: In this research, surface modification was carried out on aluminium alloy 6061 through friction stir processing by embedding surface with B4C particles. Three different samples namely, AA6061 with only stir processing (sample 1), friction stir processed by B4C with single pass (sample 2) and by B4C multi-pass (sample 3) were developed to study the wear, corrosion and microstructural properties. The modified surfaces were characterised by carrying out using optical and scanning electron microscopes. Pin-on disc method was employed to study the wear rate on these stir processed samples. Corrosion behaviour of three stir processed samples was characterised in a 3.5 wt.% NaCl solution at 10 mV/s scan rate. From microstructural analysis, the dark zones with onion rings were seen at the nugget zone in sample 2, whereas uniform distribution with clear grain boundaries were observed in sample 3. From wear test, the wear rate for sample 1 was higher when compared with other two samples. From corrosion test, corrosion rate of sample 2 was observed to be 1.469 mm/year which is lower than sample 1 (2.868 mm/year) and sample 3 (6.127 mm/year). Corrosion resistance of sample 2 was greatly improved due to proper mechanical mixing of B4C particles.

Development of Aluminium Metal Foams via Friction Stir Processing by Utilizing MgCO3 Precursor

Abstract: Aluminium foams possess multi-functional properties and a low specific weight, making them one of the most suitable choices in the application domain of the automobile and aviation sectors, vibrating machining, and structural parts. Compared to traditional fabrication routes, friction stir processing (FSP) is gaining acceptance as it is a cost-effective, highly efficient, and innocuous process to fabricate the foam precursors from the bulk substrate. In the current study, FSP was utilized to develop a precursor with MgCO3 powder acting as the blowing agent. The FSP experiments were performed as per Taguchi’s L8 orthogonal array. The precursor was heat treated in an electric furnace at a holding temperature of 650 °C for 10 min. After the post-heat treatments, this precursor resulted in a porous structure due to the evolution of CO2 gas from the composite. The simultaneous effect of tool rotation speed, traverse speed, and shoulder diameter was investigated on the pore size and porosity of the foam produced. The composite parameter “unit stirring” is found to be closely related to the processed zone (PZ) and volume processing rate of the processed zone, pore size, and the degree of porosity. The highest porosity of 16.67% was obtained with an average pore size of 10.5 µm. The largest pore size, 17.8 µm, was observed to be associated with a porosity of 14.40%. The analysis of the Kiviat plot revealed that the values of the PZ area and volume processing rate possess a polar symmetry with unit stirring. The pore size and pore density were both found to be symmetrically distributed about the unit stirring.

Macro- and Microstructure of In Situ Composites Prepared by Friction Stir Processing of AA5056 Admixed with Copper Powders

Abstract: This paper is devoted to using multi-pass friction stir processing (FSP) for admixing 1.5 to 30 vol.% copper powders into an AA5056 matrix for the in situ fabrication of a composite alloy reinforced by Al-Cu intermetallic compounds (IMC). Macrostructurally inhomogeneous stir zones have been obtained after the first FSP passes, the homogeneity of which was improved with the following FSP passes. As a result of stirring the plasticized AA5056, the initial copper particle agglomerates were compacted into large copper particles, which were then simultaneously saturated by aluminum. Microstructural investigations showed that various phases such as α-Al(Cu), α-Cu(Al) solid solutions, Cu3Al and CuAl IMCs, as well as both S and S’-Al2CuMg precipitates have been detected in the AA5056/Cu stir zone, depending upon the concentration of copper and the number of FSP passes. The number of IMCs increased with the number of FSP passes, enhancing microhardness by 50–55%. The effect of multipass FSP on tensile strength, yield stress and strain-to-fracture was analyzed.

Effect of different volume ratios of SiC and TiO2 reinforcement particles on mono and hybrid surface composites of AA7075-T651 through friction stir processing

Abstract: In the present work, the different volume ratios of silicon carbide and titanium dioxide particles were incorporated with AA7075-T651 to improve the surface properties using multipass friction stir processing. The metallurgical study of the friction stir processed samples was examined through optical microscopy and field emission scanning electron microscopy with energy-dispersive X-ray analysis. In addition, the microhardness, wear, and corrosion properties were measured and analyzed. The results revealed that the increased amount of SiC particles caused uniform particle dispersion and was devoid of cluster-rich regions within the matrix. The increased volume of SiC particles exhibited a smaller grain size due to higher grain refinement. The sample with 100% SiC showed superior mechanical, tribological, and corrosion properties. The microhardness of sample with 100% SiC was increased by 13.60% compared to base metal, it was also better compared to other composite samples. Similarly, the coefficient of friction, wear rate, and corrosion resistance properties were reduced by 43.24%, 14.98%, and 75%, respectively.

Microstructural Aspects of the Fabrication of Al/Al2O3 Composite by Friction Stir Processing

Abstract: The purpose of this work was the examination of microstructural evolution during the fabrication of an Al/Al2O3 composite by friction stir processing (FSP). In order to obtain new insight into this process, a longitudinal section of the produced composite was studied, and advanced characterization techniques (including electron backscatter diffraction and microhardness mapping) were applied. It was found that the reinforcing particles rapidly rearranged into the “onion-ring” structure, which was very stable against the subsequent dispersion. Specifically, the remnants of the comparatively coarse-scale particle agglomerations have survived even after 12 FSP passes. Therefore, it was concluded that three or four FSP passes, which are often applied in practice, are not sufficient to provide a homogeneous dispersion of the reinforcing particles. It was also revealed that the gradual distribution of the nanoscale Al2O3 particles throughout the aluminum matrix promoted a subtle reduction in both the portion of high-angle boundaries and the average grain size. These observations were attributed to the particle pinning of grain-boundary migration and dislocation slip.

Strain and damage analysis using high resolution digital image correlation in the stir zone of an AA6061-AA7075 dissimilar friction stir weld

Abstract: This work focuses on the strain and damage analysis of a micro tensile experiment of a AA6061-AA7075 dissimilar friction stir weld. Scanning electron microscopy combined with high resolution digital image correlation has been performed at two different scales to analyse strain fields and damage in the AA6061-AA7075 mixed region of the stir zone. Local alloy composition was identified as the critical parameter affecting the meso-scale strain distribution. At a finer scale, intermetallic particles also lead to strain localization within each individual alloy.

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

Abstract: 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.

Enhancement of microstructure and mechanical properties of similar and dissimilar aluminium alloy by friction stir welding/processing using nanoparticles: a review

Abstract: To decrease impacts on the environment and maintain competitiveness in the market, various industries (for example, fabrication and construction) are concentrating on minimizing material and energy usage. Aluminium (Al) and its alloys are contending possibilities for various complex applications to meet these industrial needs since they have improved qualities like good weight-to-strength ratios. Fusion welding causes the joints to deteriorate while joining Al. Friction stir welding (FSW) or friction Stir Processing (FSP) creates joints below melting point temperatures, eliminating the drawbacks of excessive heat input but necessitating an increase in the joint’s final characteristics. Nanoparticle reinforcement is an emerging field that provides great methods to create composite joints with improved joint characteristics. The surface attributes of composite joints can be improved, including hardness, strength, corrosion resistance, and wear resistance. This paper critically reviews the work carried out in the field of FSW/FSP welding AA5083 and AA6082 with carbide and oxide as reinforced nanoparticles. Further trends in nanoparticle reinforcement, oxide and carbide effect on welding parameters, microstructural formation, and mechanical properties are being analyzed. Analysis shows that the diffusion of the reinforcing nanoparticles, which affects the joint characteristics, is significantly influenced by FSW/FSP parameters. Additionally, the dispersed nanoparticles enhance joint characteristics and help refine grains. The kind, quantity, & size of reinforced nanoparticles and the welding conditions greatly influence the joint characteristics and microstructures in similar and different Al welds. Finally, prospects for a reinforced FSW are examined, followed by a look ahead and concluding notes.

Modeling and optimization of process parameters of the piston alloy-based composite produced by FSP using response surface methodology

Abstract: In this paper, A356/B 4 C composites were fabricated using the friction stir processing (FSP) method. The process’s input parameters, including rotational and transverse speed, were optimized using the response surface methodology (RSM). Three factors and three levels with nine experimental runs made up the design of the experiments. An analysis of variance (ANOVA) was employed to determine whether the constructed model was adequate at a 95% confidence level. This study found that transverse speed was the most critical variable affecting the composites’ silicon (Si) particle size, UTS, and force. The findings demonstrate that the Si particle size of the parent material and the dispersion quality of B 4 C particles in the aluminum matrix are considerably influenced by the FSP factors, such as rotating speed and transverse speed. Second, tests for tensile strength were conducted to examine the composites’ mechanical properties. Then, using a specially designed fixture to measure force during the process, the forces on the tool, which play a decisive role in determining the tool’s life, were measured in different input parameters. The findings demonstrate that FSP transforms the mechanism of the fracture from brittle to extremely ductile in composites from the as-received metal.