Friction Stir Processing Research Articles (Page 1)

ABSTRACT Achieving uniform dispersion of ceramic reinforcements in magnesium alloys remains a significant challenge owing to particle agglomeration and poor wettability. Additionally, ensuring long-term corrosion resistance in aggressive environments is difficult because of microstructural heterogeneity and localised galvanic coupling. The present study investigates the fabrication of AZ61-ZrO₂ surface composites using friction stir processing (FSP) and evaluates the effect of varying ZrO₂ concentration (2, 4, 6, and 8 wt.%) on microstructural evolution and corrosion behaviour. Microstructural analyses revealed that all FSPed composites experienced notable grain refinement and precipitate modification, with 6 wt.% ZrO₂ produced the most refined grains and a highly uniform microstructure. XRD confirmed the existence of α-Mg, β-Mg₁₇Al₁₂, ZrO₂, and minor MgO without forming new intermetallics, indicating reinforcement stability. Corrosion testing showed a strong dependence on ZrO₂ content. The 6 wt.% ZrO₂ composite exhibited superior performance, with the most positive Ecorr, and the lowest corrosion rate. Conversely, 2 and 8 wt.% ZrO₂ samples suffered severe localised attack due to particle clustering and precipitate segregation, while minimal pitting occurred at 6 wt.%. These results confirm that 6 wt.% ZrO₂ offers the optimal combination of grain refinement, passive film integrity, and corrosion resistance.

In the present study, aluminum matrix composites (AMCs) were fabricated by friction stir processing (FSP) using Ni-Cu particles. Ni-Cu particles were added to the Al matrix in two ways. First, without any treatment and in the form of a mixture of as-received powders. Second, treated through mechanical alloying to form Monel solid-solution particles. The particles were added to a groove to be processed by the FSP tool to produce a local AMC. To investigate the kinetics of intermetallic compounds (IMCs) growth in reinforcement particles, the produced AMCs were annealed at 500 °C for 2 h. To characterize the reinforcing particles, several analyses were performed on the samples. Field-emission scanning electron microscopy (FE-SEM) was used to study the size, morphology, and IMC thickness. TEM was performed to characterize the IMCs through high-resolution chemical analyses. Tensile testing was used to understand the mechanical properties and fracture behavior of AMCs. Tensile testing revealed a noticeable improvement in strength for the as-mixed sample, with a UTS of 90.3 MPa, approximately 22% higher than that of the base aluminum. In contrast, the mechanical alloying sample with annealing heat treatment exhibited a severe drop in ductility, with elongation decreasing from 17.98% in the as-mixed sample to 1.52%. The results showed that heat treatment thickened the IMC layer around the reinforcing particles formed during the FSP process with as-mixed particles. In the AMC reinforced with mechanically alloyed Ni-Cu powders, IMC formation during FSP was significantly suppressed compared to that of as-mixed particles, despite the finer size resulting from milling. Additionally, the heat treatment resulted in only a slight increase in IMC thickness. The IMC layer thickness after heat treatment in both the mechanically alloyed sample and the as-mixed sample was approximately 2 µm and 20–40 µm, respectively. The reason behind this difference and its effect on the fracture behavior of the composite were elaborated in this study, giving insights into metal-matrix production with controlled reaction.

Friction stir-based joining techniques offer a promising route for the integration of highly dissimilar materials into single structures, with potential applications in safety-critical sectors such as hydrogen storage and lightweight mobility systems. Ensuring structural integrity under dynamic loading is crucial for their industrial adoption, particularly given the strong inhomogeneity of metal–polymer interfaces. This study investigates the strain rate sensitivity of lap joints between an AA6082-T6 aluminum alloy, and a glass-fiber-reinforced polymer (Noryl™ GFN2) produced using a friction stir process. Quasi-static and intermediate strain rate (≈3 s−1) tensile tests were performed on the joints, while both base materials were additionally characterized at quasi-static, and intermediate strain rate conditions using a custom accelerated electromechanical testing device. Digital image correlation was employed to monitor deformation. The results reveal that the joints exhibit clear strain rate sensitivity, with ultimate remote stress and bending angle stiffness increasing by approximately 30% and 23%, respectively, from quasi-static to intermediate strain rate loading. Fracture consistently initiated in the polymer, indicating that the joints mechanical performance is limited by the polymeric constituent, although the polymer strain rate hardening impacts the peel/shear mix in the loading scenario of intermediate strain rate loading. Overall, the findings highlight that while friction stir metal–polymer joints benefit from strain rate hardening, their performance envelope remains governed by the polymer base material.

Abstract Powder-based friction stir additive manufacturing employs various methods to deliver powder to the deposition zone, which can influence the deposits' microstructure by altering how the powder interacts with the tool. However, this area has not been extensively explored in existing research. To investigate this, AA6061 powder was deposited using two powder-based techniques: additive friction stir deposition (P-AFSD) and additive friction stir processing (AFSP). The resulting microstructural evolution was subsequently analyzed to establish correlations with each method's respective deposit formation mechanisms. The AFSP microstructure exhibited ∼20% more recrystallized grains than P-AFSD, but contained ∼1% fewer high-angle grain boundaries. This may be due to the powder material undergoing deposition and recrystallization under relatively higher temperature and deformation conditions during AFSP, followed by additional strain as most of the tool's front and entire rear section passed over the deposited material. Texture evolution was examined using pole figures and orientation distribution functions. The initial extrusion of partially plasticized material through the central hole of the P-AFSD tool led to a strong presence of A-type textures and the absence of any plane strain component. Moreover, the average Vicker's microhardness was 78 HV for P-AFSD and 65 HV for AFSP.

A novel strategy to control degradation rate via interface solute segregation in a surface-modified AT42-xCa alloy by friction stir processing

Osteoblastic differentiation and antibacterial activity of reduced graphene oxide modified titanium alloy implant surfaces prepared via friction stir processing

Effect of heat treatment on microstructure evolution mechanism of hydrogenated TC4 alloy via friction stir processing

In-situ TiC-reinforced titanium nanocomposite synthesized via multi-pass friction stir processing with nanodiamond additions

Friction stir processing of AA6063-Ni particulate composite for fan exit guide vanes in high bypass ratio gas turbine engines

Enhanced strength and ductility in wire-arc directed energy deposited Al-Mg-Sc alloy assisted by interlayer friction stir processing

The study examines the effects of the Friction Stir Processing (FSP) process on the EN AW 5754 aluminium alloy, conducted under underwater conditions. FSP is an innovative technology used to improve the mechanical properties of materials through plastic deformation. Fracture surface analysis is essential for understanding how the process influences the internal structure of the alloy and its behaviour during fracture. The results obtained from the fracture analysis provide insights into the deformation mechanisms and how processing conditions affect the material's structural integrity. This study contributes to the development of aluminium alloys with enhanced properties, with applications in fields such as the automotive and aerospace industries.

Abstract Friction stir processing (FSP) has emerged as an effective technique for enhancing the mechanical and microstructural properties of metal matrix composites. This study investigates the influence of FSP parameters on the mechanical characteristics and microstructure of AZ31B magnesium alloy reinforced with silicon carbide particles of size APS < 80 nm. The method employed here is a hole method for reinforcement and designed with an L9 orthogonal array to analyze the effects of tool geometry, rotational speed, traverse speed, and hole diameter. The experimental findings indicate that a cylindrical threaded tool pin profile, a 0.8-mm hole diameter, a rotational speed of 765 revolutions per minute, and a traverse speed of 31.5 mm/min resulted in the most optimal combination of mechanical properties, including improved tensile strength, micro-hardness, and elongation. Microstructural analysis revealed a uniform distribution of SiC particles, leading to grain refinement and enhanced material performance. These results demonstrate that FSP is a sustainable approach for fabricating high-performance magnesium-based composites, making them suitable for applications in aerospace, automotive, and biomedical industries.

Friction stir processing is a research domain in a continuous dynamic that has led to the development of some variants of its application. One of the variants is submerged friction stir processing to avoid excessive heating of the processing tool and the materials to be processed. The paper presents the results of the experimental research carried out at ISIM Timisoara regarding the submerged friction stir processing (SFSP) of the EN AW 5754 aluminum alloy with a thickness of 3 mm. SFSP processing was performed in one pass and in multiple passes using a processing tool having conical pin with four flat chamfers and different processing parameters. To evaluate the processed material, structural analyses, hardness measurements, as well as mechanical tensile and static bending tests were performed.The preliminary experimental research carried out within the ongoing Nucleu PN 23 37 01 02 project shows favorable results in the SFSP processing of the EN AW 5754 aluminum alloy.

Tribological behavior of Al–Mg alloy with additions of Fe, Ni, and Ti metallic powders introduced by friction stir processing

Submerged friction stir processing is a variant of processing metallic materials that is based on the principle of FSW welding and which considers the local modification of the mechanical properties and the microstructure of the material to be processed. By carrying out the underwater SFSP processing, the thermal overload of the material to be processed and that of the processing tool is reduced, thus contributing to the reduction of the dimensions of the heat affected zone and of the deformations of the processed material, as well as to a greater durability of the tool. The paper presents results obtained by ISIM Timisoara regarding the submerged friction stir processing (SFSP) of the EN AW 1200 aluminum alloy with a thickness of 5 mm. The SFSP processing was done in multiple passes using a steel processing tool, with a conical pin with four flat chamfers and different processing parameters. The positive preliminary results are useful for complex experimental research on SFSP processing of aluminum alloys, which will be carried out within the ongoing Nucleu project PN 23 37 01 02.

The greater challenges in the manufacturing and machine tool sectors are the periodic replacement of moving components due to wear, and its subsequent escalated product cost. The present research aims to address the issue by developing of novel lightweight surface composite reinforced with hybrid particles SiC and Y2O3 processed through the Friction Stir Process (FSP). The test specimens were prepared by FSP by following four different wt.% of hybrid particles. The sliding tribological examination was executed to examine the wear characteristics of the surface composite at both ambient and elevated temperature environments. The achievement of dynamic recrystallisation is acknowledged through microstructure and grain size analysis results that reveal the finer grain structure at the nugget zone with the smaller grain size. The wear assessment outcomes endorse the improved wear characteristics of the Al-3SC-1Yo variant by upholding its 126% and 53.88% higher wear resistance than the base material at ambient and elevated temperatures, subject to the normal load of 45 N. The post-worn-out surface analyses proclaim that ambient wear is driven by adhesion, two and three-body abrasion, whereas elevated temperature wear is driven by pure abrasion. It is comprehended from the wear results that 90% more wear loss is recorded during the elevated temperature than the same in the ambient environment. The quantitative comparison of ambient and elevated temperature wear through the observation of surface topography, and the inclusion of hybrid reinforcement on unique base materials are the key novelties of the proposed study.

ABSTRACT The present study investigates the effect of microstructure evolution, including grain refinement and grain orientation, on the surface residual stresses of friction stir processed (FSP) Al6061 alloy. Grain rotation, dynamic recrystallization (DRX), and grain boundary migration are all induced by the FSP process, which results in notable microstructural alterations. According to EBSD analysis, the original S-rolling texture changes into Brass and Goss textures while grain size decreases and high-angle grain boundaries (HABs) increase. The residual stress distribution measured at various depths is correlated with these microstructural alterations, because of the severe plastic deformation and thermal cycles after FSP, residual stresses close to the surface become extremely compressive, reaching a maximum negative value of −564 MPa at 500 µm depth. Residual stresses change from compressive to tensile at deeper depths; at 2000µm and reaches 375 MPa. The relationship between residual stress redistribution and microstructural evolution shows that stable textures and finer grains lead to a more advantageous residual stress state. FSP significantly reduced wear depth and coefficient of friction by fine-tuning the grain structure and increasing the high-angle grain boundary content. Following FSP, SEM images revealed smoother surfaces with minimal damage.

Microstructure and Mechanical Property Enhancement of Cold Spray Additive Manufactured Al2O3/2024 Aluminum Matrix Composites through Thermo-Mechanical Coupling: A Case Study on Friction Stir Processing and Hot Rolling

Overcoming the strength–ductility trade-off in conventional aluminum matrix composites (AMCs) remains a significant challenge. This study employs dual-scale hybrid reinforcement particles comprising micron-sized Cu and nano-sized Ti, alongside bimodal micro-sized pure Al powders as matrix fillers. The AMCs were fabricated through ball milling (BM) combined with multi-pass friction stir processing (FSP). The homogenously distributed hybrid reinforcement particles generate an integrated composite region consisting of both coarse-grained (CG) and fine-grained (FG) structures, demonstrating enhanced material characteristics. The interwoven network of coarse- and fine-crystalline domains constructs a heterogeneous architecture that enables simultaneous improvement in both strength and ductility properties. The micron-Cu acts as a skeletal support within the matrix, enhancing load transfer efficiency and effectively hindering dislocation motion. The nano-Ti and in situ intermetallics facilitate grain refinement via the pinning effect and promote heterogeneous nucleation, which contributes to stress dispersion and dislocation obstruction. The addition of dual-scale micron-sized pure Al powder particles promotes the formation of the heterogeneous architecture, which enhances the balancing of strength and ductility in the composite. Following compositing (Al10-5Cu-10Ti-10Al20), the alloy exhibits an ultimate tensile strength (UST) of 267 MPa, a hardness of 98 HV, and an elongation of 16.7%, representing increases of 193.4%, 226.7%, and 9.9%, respectively, relative to the base metal.

ABSTRACT AA7075 surface composites with improved hardness, tensile and flexural strength are highly preferable in aerospace sector like wing and fuselage sections and in automotive industries for piston and cylinder liner applications. In order to achieve this, Friction Stir Process (FSP) is adopted in the fabrication of Surface Composites (SCs) with Reduced Graphene Oxide (RGO) as reinforcements using tapered cylindrical pin tool with appropriate process parameters. Microstructural examination affirms that equiaxial grains with fine structure is formed in the stir zone region. Addition of RGO particulates subsequent to five passes lead to curtail the grain size to 9 ± 0.7 µm in comparison to base metal (79 ± 5.4 µm). The immaculate interface are formed between the base metal and the RGO, which is evident in TEM. XRD confirms the phase of reinforcement particulate and absence of intermetallics. Herewith, elemental mapping confirms the reinforcement along with base metal. RGO 5 Pass specimen attains superior microhardness (292.9 ± 3VHN) which increases to 60.9% in comparison to the base metal (182 ± 4VHN) owing to the homogenous dispersion strengthening mechanism accompanied with reduced grain size. Orowan strengthening and the RGO particulates surrounded by reduced oxygen content at five number of passes (withstand more load) are responsible for the enhanced tensile strength (758 ± 3MPa). Despite this, reduced ductility is obtained through fragmentation of fine grains and fractography that dictates the tensile failure mechanism as both ductile and brittle. Whilst, inherent toughness of both AA7075 and RGO particulates at 5 passes significantly improves the flexural strength (126.8 ± 1.4N/mm2) with reduced deflection (19 ± 1.1 mm). Furthermore, the variation of microstructure behavior in the bend sample is discussed.