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Friction stir processing (FSP) is used for changing the microstructure and material properties improvement. In modern years, special attention is exposed by governing the temperature level, and is applied by various coolants spraying on the top surface of the sample during FSP. This review paper explores the impact of several cooling mediums such as normal water, cold water, hot water, and cryogenic on the temperature distribution, grain refinement, mechanical characteristics, and superplastic deformation behavior of FSP using various grades of magnesium (Mg) alloys. It also includes the corrosion rate and wear behavior of FSP on Mg alloys. Through the systematic review, it has been observed that refined grains were formed and the generation of intermetallic compounds was suppressed after FSP in underwater and cryogenic conditions, leading to a notable increase in strength. The higher tensile strength and elongation are exhibited while using cryogenic compared to water medium. This is due to a rapid cooling process, where the high temperature was short for the newly-formed grains to fully develop. This review not only concludes the key findings of the preceding research but also suggests future recommendations. [ABSTRACT FROM AUTHOR]

Aluminum-based composite layers with different TiB2 contents were prepared by implanting TiB2 reinforcement powders with mass fractions of 1%, 3%, 5%, and 7% into 7075 aluminum alloy sheets using Friction Stir Processing (FSP) technique. The influence of TiB2 content on the friction and wear performance of the modified aluminum-based composite layers was investigated. The results showed that the incorporation of TiB2 reinforcement powders can reduce the friction coefficient and wear volume of the materials, thereby improving the friction and wear performance. Moreover, as the mass fraction of TiB2 reinforcement powder increases, the overall friction coefficient and wear volume of the composite materials exhibit a gradual decrease trend, with adhesive wear being the predominant wear mechanism. [ABSTRACT FROM AUTHOR]

Having homogenized the as-cast AlCoCrFeNi2.1 high-entropy alloy followed by cold rolling and subsequent annealing, this study produces surface nanocomposite using friction stir processing (FSP). Three weight percentages of SiC nanoparticles sized between 45 and 60 nm were added during FSP. The microstructural evolutions and corrosion behavior were assessed after and before FSP. As part of the investigation, a series of potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) were conducted in a 3.5 wt% NaCl solution. Through friction stir processing, the initial microstructure underwent significant modification due to dynamic recrystallization and the Zener pinning applied by SiC-reinforcing nanoparticles. The hard B2 phases, which function as preferred sites for localized corrosion, were broken and redistributed during FSP, resulting in a notable increase in corrosion resistance. After performing FSP, the cold-rolled and annealed sample exhibited a significant increase in corrosion resistance, from 1.7 kΩ.cm2 to 129.4 kΩ.cm2.

Abstract To fundamentally investigate the influence of different friction stir processing (FSP) strategies, namely raster, spiral, and parallel in various passes on the surface integrity of hybrid aluminum nanocomposites reinforced by titanium oxide (TiO2), silicon carbide (SiC), and zirconium oxide (ZrO2) nanoparticles, various examinations were conducted. The surface integrity, comprising microstructural characterization, elemental composition, surface topography, roughness, waviness, and microhardness was studied by different analyses, including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), optical microscopy (OM), atomic force microscopy (AFM), and Vickers microhardness machine in different zones. Results demonstrated that surface integrity and quality are dependent on the type of FSP strategy. SEM images revealed that a homogeneous distribution of the nanoparticles in the matrix is obtainable by the parallel and raster FSP strategies. Roughness and waviness measurements illustrated that the surface topography of the hybrid nanocomposite was symmetrical and improved by raster strategy and TiO2 + ZrO2 nanoparticle reinforcement. Furthermore, the two-pass FSP improved the arithmetic average surface value (Ra) such that the Ra of two passes decreased by 32.5% compared to a single one. The mean microhardness in the spiral, raster, and parallel pass strategies increased by ~ 45%, 37%, and 31%, respectively.

Friction stir processing (FSP), as an advanced technique, was employed to fabricate in situ aluminum composites with the aim to elucidate the correlation between microstructure and mechanical properties of the obtained composites. The novelty of the work is to utilize simultaneous incorporation of Fe and Cu powders into the friction stir zone in order to fabricate in situ aluminum composites. To achieve the goal, the loading content of Cu and Fe powders and the process pass number (1 pass to 5 passes) were altered. While the total loading content of Fe and Cu powders was kept constant, the weight percentages of these reinforcements were varied (25%, 50%, and 75%). Microstructural characteristics were examined using scanning electron microscopy and optical microscopy. Five passes FSP resulted in smaller grain sizes of the Al matrix, smaller and less agglomeration of the reinforcements as well as homogeneous dispersion of the reinforcement features and thus, enhancement of the mechanical properties of the composites. X-ray analysis and energy dispersive spectroscopy confirmed in situ formation of Fe-Al and Al-Cu intermetallic compounds in the composites. The tensile testing outcomes proposed the 50wt% Fe-50wt% Cu/Al composite fabricated in 5 passes as the optimum formulation achieved in this research. This can be attributed to the smaller grain size of the matrix in the friction stirred zone and more homogeneous dispersion of the reinforcements in the matrix. Furthermore, this strengthening was affected from the presence of more amounts of well dispersed intermetallic compounds in situ formed during 5 passes. The average tensile strength (207 MPa) and hardness (73 Vickers) of the composite were approximately 175% and 160% greater than that of the unreinforced aluminum (75 MPa, 28 Vickers), respectively. Increasing the process pass number from 3 to 5 passes not only had strengthening and hardening effects but also improved the composite elongation at break. [ABSTRACT FROM AUTHOR]

High-strength brass is commonly used to produce sliding parts; however, its wear resistance should be further improved to extend the service life and performance of machinery and equipment constructed using this material. In this study, friction stir processing (FSP), a technology based on friction stir welding, was used to improve the wear resistance of high-strength brass. Because the application of FSP requires subsequent finishing operations on the workpiece, milling and wire electrical discharge machining (WEDM) have been implemented and their effects on the surfaces modified by FSP were investigated. FSP refined the crystal grains, resulting in improved hardness from 240 to 300 HV. Sliding tests were conducted to evaluate the friction and wear properties under three conditions: without FSP, with FSP and milling, and with FSP and WEDM. After applying FSP and milling, the wear amount decreased by 15%, in other words, the wear resistance improved compared with that observed without FSP. With FSP and WEDM, the wear resistance did not improve.

This investigation deals with the microstructural and mechanical behaviours of friction stir processed (FSPed) commercially available pure magnesium with different tool profile geometry. The micro-level properties were assessed through in-situ micro-pillar compression which showed that FSPed material experienced significant plastic deformation and even re-distribution of residual oxide particles which was present in the cast magnesium together with grain refinement (from 3.4 μm to 2.6–2.7 μm). These changes in microstructure contributed to raise the compressive and yield strengths of the FSPed magnesium, up to 99 MPa and 94 MPa respectively, compared to 33 MPa of cast magnesium, when triangular tool profile was employed. Furthermore, the deformed material acquires ductile breakage with improved plasticity (micro-necking) irrespective of processing conditions, that is, either cast or friction stir processed.

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. [ABSTRACT FROM AUTHOR]

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This paper investigates the thermal-pseudo mechanical (TPM) model's residual stress prediction capability for its utility in developing friction stir processing (FSP). Specifically, two FSP tests under different processing conditions were conducted, and the corresponding simulations were carried out to verify if the TPM model can predict residual stresses for various tool radii and workpiece materials. The model successfully predicted residual stresses with an error less than 4% for one of the tests but failed to work for the other test. Further simulations under different FSP conditions proved that the TPM model works for cast aluminum alloys and wrought aluminum alloys. In addition, the large FSP tool used was found to be the reason for the model's failure on one of the tests. This indicates that there is a range of tool radii for which the TPM model is applicable. As a solution, this paper suggests modifications to the TPM model based on calibration to the FSP test temperatures. The resulting residual stress prediction is accurate and differs from the experimentally characterized stress values by only 6.5 MPa. The calibrated TPM model requires FSP to be carried out when using a tool with a different radius. Following that, the effect on residual stresses due to changes in the other process parameters, such as the tool traverse & rotation speeds and the clamping conditions, can be predicted. [ABSTRACT FROM AUTHOR]

In this investigation, the AA5083/316 stainless steel (ss) surface composite was generated by the friction stir processing (FSP) with the aim of improving the mechanical properties, the corrosion and tribological performances of the composite. The FSP process was conducted at different tool pass numbers (1-P, 2-P, and 4-P) and a constant tool rotational (900 rpm) and travel (85 mm/min) speeds. To analyze the microstructure of the samples, optical (OM) and scanning electron microscopes (SEM) were employed to characterize the scattering of the 316 stainless steel (ss) particles within the AA5083 matrix. It was found that multi-pass FSP resulted in substantial grain refinement from 7.02 to 5.89 μm and better scattering of the reinforcement in the AA5083 Al matrix. Results also indicated that the mechanical and wear properties of the composite layers were enhanced by increasing the pass number from 1-pass to 4-pass, which can be credited to the formation of finer 316 stainless steel (ss) particles appropriately dispersed in the Al substrate. Furthermore, the results depicted that the corrosion resistance of the samples is enhanced with the increase of pass number. [ABSTRACT FROM AUTHOR]

Friction stir processing (FSP) with high rotational speeds was successfully adopted to fabricate nano-hydroxyapatite (nHA)-reinforced ZK61 magnesium matrix composites (MMCs). And the influence of high rotational speeds on ZK61-nHA composites manufactured by FSP was investigated. The microstructure studies indicated that a higher rotational speed for FSP contributed to the formation of grain refinement and the uniform distribution of nHA particles. The average grain size was refined from 150 to 2.8 and 2.2 μm at the stirred zones of FSP ZK61 and ZK61-nHA composites, respectively. And the uniformity and average values of microhardness were also positively correlated with the increase in rotational speeds. Moreover, corrosion tests revealed that samples prepared at 5000 rpm obviously had better corrosion resistance (Ecorr = −1.484 V and Icorr = 1.536 × 10–5 A/cm2), which greatly improved the relative growth rate (RGR) of ZK61-nHA samples to 81.60% in the CCK-8 cell viability assay. [ABSTRACT FROM AUTHOR]

This study investigates the manufacturing of Aluminum-Alumina composites through Friction Stir Processing (FSP) and explores the resultant enhancements in mechanical properties. A key focus lies on achieving a uniform distribution of Al2O3 particles within the composite matrix, crucial for optimizing material performance. These dispersed particles act as effective strengthening agents, impeding dislocation movement and grain boundary migration, consequently improving mechanical attributes such as hardness, strength, and wear resistance. Experimental findings underscore the efficacy of FSP in enhancing various mechanical properties of the composite. Notably, significant improvements were observed, including a 23.56% increase in tensile strength, a 37.9% enhancement in hardness, a 25.5% improvement in fatigue strength, and a notable 30.12% increase in wear resistance. These results underscore the potential of Aluminum-Alumina composites manufactured via FSP to unlock new opportunities for high-performance materials in industries requiring superior mechanical properties and wear resistance, such as aerospace, automotive, and manufacturing sectors.

In the present work, the nanocomposite AlCoCrFeNi2.1 high-entropy alloy was produced using friction stir processing (FSP). SiC nanoparticles were distributed on the surface via the stirring action imposed by FSP. The size and weight percent of added nanoparticles were 45–60 nm and 3wt.%, respectively. The applied rotating and transverse speeds were 800 rpm and 50 mm/min, respectively. The microstructural evolutions, the hardness changes and the shear properties were evaluated after applying FSP. These studies were carried out using X-ray fluorescence (XRF), optical microscopy, scanning electron microscopy (SEM), energy dispersive X-Ray analysis (EDS) and X-Ray diffraction (XRD). Also, the mechanical properties were investigated using Rockwell C and Vickers hardness testing as well as shear punch testing (SPT). The initial microstructure was significantly modified due to the occurrence of dynamic recrystallization as well as Zener pinning applied by nanoparticles. During the FSP, the SiC nanoparticles along with the broken B2 phases were distributed uniformly in the matrix. The microstructural changes resulted in an increase in the hardness and shear strength from 308 HV to 480 HV and 344 MPa to 407 MPa, respectively for initial and FSPed cases.

Magnesium and its alloys have become a great sparking topic of research due to their excellent biocompatible and biodegradable behavior. Magnesium and several biocompatible alloying elements were developed long back. The trends are to develop a surface composite of as-cast Mg alloys to control the degradation behavior. In this work, the surface composites of AZ31–TiO2 were developed by friction stir processing (FSP). The influence of spindle speed or tool rotation speed and number of processing passes on mechanical and microstructural performance were analyzed. The tool rotation speeds 720, 1050, 1550 and 2260RPM with pass 1, pass 2 and pass 3 were considered. The FSP workpiece was analyzed by microstructure and universal testing machine and the significant improvement in grain refinement and hardness was observed. [ABSTRACT FROM AUTHOR]

Magnanimously Aluminium metal matrix composites (MMCs) are acknowledged worldwide for keeping exceptional strength to weight ratio for which these are incorporated extensively in Aerospace and Automobile industries and gained potential limelight. Moreover, the material response outreach potential or the composite functionality potential are exclusively driven by tuning of the reinforcement materials. Herein, Al composites were concocted by introducing micro and nano Boron Carbide (B 4 C) powder into aluminium alloy AA 7075-T6 material matrix through Friction Stir Processing (FSP) with a motivation to enhance the mechanical and damping properties. Further the influence of physical structure alteration of reinforcement B 4 C from micro to nano dimension on the composites were validated through various characterizations. The microstructure of the composites was observed with optical microscope and Electron back scattered diffraction (EBSD) methods respectively. A significant grain refinement was observed with nano-reinforced composite by clinching average grain size reduced to 2.9 μm relative to base material grain size of 37 μm. The average hardness of nano-reinforced MMCs was found to be 66% higher than base material recorded a value of 141 HV. Furthermore, the AA7075-T6 composites were studied for their thermal and mechanical cyclic damping performance in the temperature range from ─ 60 to 60 °C and depicted exceptionally good damping property. [ABSTRACT FROM AUTHOR]

This research investigated the effect of tool geometry, rotation, and advancing speed on the microstructure and mechanical properties of aluminum AA6061-T6/graphene nanocomposites fabricated by friction stir processing (FSP) using three conical tools with the pin cone angles (PCAs) of 2, 2.5, and 3°. In the first step of the study, the process was performed with and without graphene nanoplatelets (GNPs) at different rotations (710, 1120, and 1400 rpm) and advancing speeds (80, 125, and 160 mm/min). The yield strength, tensile strength, and microhardness of all the samples were lower than those of the base metal. In the second step of the study, the heat input was controlled by reducing rotations (112, 180, and 280 rpm) and advancing speeds (31.5, 25, and 20 mm/min). The mechanical properties of processed samples were studied by tensile tests and microhardness measurements. Microstructural evolution in samples was analyzed by means of a field emission scanning electron microscope (FESEM) equipped with an X-ray energy dispersive spectrometer (EDS) and electron back-scattered diffraction (EBSD) detector. The results indicated that the mechanical properties were improved in the second step with the increase in the advance per revolution (APR) and the PCA. This was linked to the microstructure evolution in the processed samples affected by process parameters and regulated heat input. The effect of each input variable on the mechanical properties was evaluated by statistical analysis and was validated by analysis of variance (ANOVA). The optimal processing was attained by utilization of PCA, tool rotation, and advancing speed. • AA6061/graphene nanocomposites were fabricated by FSP using conical pins. • The influence of the pin geometry, tool rotation, and advancing speed was examined. • Heat input control and proper distribution of graphene increased the YS and UTS. • Grain refinement was performed by adjustments in process parameters, PCA, and APR. • ANOVA was conducted to determine the effects of APR and PCA on strength/hardness. [ABSTRACT FROM AUTHOR]

Pursuing lightweight materials in the automotive and aerospace industries, driven by environmental concerns and fuel efficiency goals, has increased interest in magnesium alloys. The RE-based WE-series exhibits superior properties, making it a compelling candidate for various applications. However, inherent limitations, including low ductility, hardness, and strength, necessitate further enhancements. In this study, an effort is being made to fabricate Metal Matrix Composites (MMCs) through Friction Stir Processing (FSP) using WE43 Mg alloy as matrix and NiTi, Fe, and Sn as hybrid reinforcement particles. The study involved varying the composition of the reinforcement particles, and the analysis of hardness, ductility, and strength was conducted and compared with the base material. The results indicate that the samples processed with hybrid reinforcements using FSP effectively refine the microstructure, leading to improved properties. The highest hardness (81.3 HV), and strength (176 MPa), were observed in the S3 sample. The maximum ductility/strain percentage of 21.9 % was attained in the S2 sample. This research introduces innovative possibilities for expanding the application scope of magnesium alloys, addressing challenges, and capitalizing on their unique properties. • Friction Stir Processing efficiently eliminated dendrites. • Average grain size of 4.2 μm is observed in the FSPed sample. • The reinforced samples exhibit a grain size as small as 2.7 μm. • Increment of 40 % in hardness and 46 % in strength is observed in S3 sample. • An increase of 67 % in ductility is observed in S2 sample. [ABSTRACT FROM AUTHOR]

The magnesium alloys are considered as biodegradable implant materials due to its biocompatibility and mechanical properties. The light weight structure also made it more demanding in industries such as automobile and aerospace. The other properties which made magnesium more versatile are its strength to weight ratio, ductility and corrosion resistance. In this review article, Mg alloys is considered to understand the change in microstructure after various severe plastic deformation (SPD). Various SPD such as rolling, friction stir processing (FSP), equal channel angular pressing (ECAP) and high pressure torsion (HPT) are used to understand the modification of microstructure. The influence of microstructure change is explained in terms of change in mechanical properties. It is observed that the alteration of microstructure by SPD can enhance the mechanical properties and corrosion resistance. The enhancement in mechanical properties after severe deformation is observed due to the existence of various strengthening mechanism such as grain refinement, dynamic re-crystallisation, grain boundary strengthening, dispersion of micro/nano precipitate of second phase and improvement in dislocation strengthening. Additionally, crystallographic texture helps to improve the mechanical properties after severe plastic deformation in Mg alloys. [ABSTRACT FROM AUTHOR]

Friction stirring based “Green” processes are ruled by geometrical and process aspects of the tools used for generating desired properties in the processed materials. Considering only geometrical aspects, the developments in tool geometry, its modifications with the time, profiles and their corresponding impacts on the property generation are addressed in the present work. It is a censorious and judicious review which consolidates the relevant information apropos of all geometrical aspects of tools and their roles in property generation.

Friction stir processing (FSP) was employed to synthesis ex-situ Al5083 nanocomposite reinforced with different mechanically-alloyed aluminium nanocomposites containing carbon nanotubes (CNTs) and ferric oxide (Fe2O3). The mechanically-alloyed nanocomposite reinforcements were initially prepared using ball milling and introduced into the stir zone (SZ) of rolled Al5083 alloy during subsequent FSP. The FSPed nanocomposites were successfully processed with uniform dispersion of CNTs and Fe2O3 nanoparticles resulting in the achievement of unique properties. Addition of nanocomposite reinforcements significantly reduces the grain size of FSPed nanocomposites. The least grain size belongs to hybrid FSP5 (Al/CNTs/Fe2O3) nanocomposite with grain size of 6.9 ± 0.4 μm which is 7.4 and 2.6 times smaller than base metal (BM) and un-reinforced FSPed (FSP1). Microstructure of FSP5 nanocomposite contain largest fraction of high angle grain boundaries (HAGBs) of 87 %. Among all FSPed nanocomposites, hybrid FSP5 nanocomposite has the best mechanical properties in the terms of microhardness, Yield strength, ultimate tensile strength and wear resistance; with 1.6, 2.7, 3.5, 3.1 times, respectively, superior to BM. The significant improvement is attributed to the desirable microstructural changes including well dispersion of nanoparticles and extensive grain refinement. Hybrid FSP5 has an excellent magnetic and electrical resistivity when compared with the BM, however, its magnetic properties is slightly slower than FSP4 specimen due to de-magnetization effect of CNTs.

The strength-ductility trade-off problem of carbon nanotube (CNT) reinforced aluminum matrix nanocomposites (AMNCs) restricts its further application. Hence, we report the fabrication of nano-Al4C3 reinforced AMNCs through friction stir processing (FSP) on CNT/Al composites which can simultaneously elevate the ductility of the composite and maintain the original strength. The microstructure evolution and the dispersion of reinforcement are investigated. Tensile tests show that the elongation of the Al4C3/Al composites fabricated via FSP at a rotation rate of 800 rpm increased by 1.6 times than that of CNT/Al composite and the yield strength retained 95%. The improvement of the mechanical properties is due to the strong Al4C3–Al interface, homogeneous dispersion, nano size, and dynamic recrystallization during FSP. Grain refinement and Orowan strengthening are the main strengthening mechanisms of Al4C3/Al composites. This research shares an approach to preparing a nano-Al4C3 reinforced aluminum matrix composite with well strength and outstanding ductility.

This paper presents a review of important aspects related to the Friction Stir Welding and Friction Stir Processing (FSW/FSP) concepts. The FSP, as a variation of the FSW, uses the same principle, but instead of the material joining, the FSP focuses on a surface modification aiming at improving surface properties of the substrate material. Thin surface composites can be made either by using grooves or drilled holes. FSP process parameters have been elaborated: axial force, rotational and traverse speed, tilt angle, insertion depth and tool geometry, as well as number of passes. Review of the used materials in fabrication of composites by using FSP is shortly presented. Effects of the FSP on mechanical properties have been discussed: effects on the microstructure, hardness and wear properties, tensile strength, and fracture and defects formation. FSP has evolved as an efficient method to modify surface structures, especially important for metallic materials that exposed to different harsh conditions, and further research will enable its wider use in industry.

This work aims to determine and select the suitable friction stir processing parameters for recycled aluminum alloy 6063 surface composites reinforced with titanium dioxide for better tribological performance. A medium range of processing parameters (1200–2000 rpm, 25–45 mm/min) were used to compare with a unique relatively high rotational speed of 2442 rpm and feed rate of 50 mm/min for the sample fabrication. The surface composites' microhardness was measured and the friction and wear performance were tested using the pin-on-disc tribo-tester under starved lubrication conditions. The results show that surface composites produced at a high rotational speed of 2442 rpm and feed rate of 50 mm/min improved 45% in surface microhardness and reduced the friction coefficient and wear rate by 39% and 73%, respectively, compared to the substrate material. [ABSTRACT FROM AUTHOR]

To enhance the properties of TC4 titanium alloy samples prepared by Laser Metal Deposition (LMD), while minimizing metallurgical defects and increasing relative density of the samples, the advanced Friction Stir Processing (FSP) technology was employed to conduct a refined secondary modification on the LMD-deposited TC4 titanium alloy samples. The comprehensive influences of FSP on the microstructure and properties of the as-deposited TC4 titanium alloy were emphatically investigated. The results reveal that the as-deposited TC4 titanium alloy exhibits a microstructure characterized primarily by columnar grains interspersed with a minor amount of equiaxed grains in the vertical section. After FSP treatment, the microstructure transforms into a new morphology where more refined equiaxed grains coexist with bimodal structures. Meanwhile, on the horizontal plane, the existing equiaxed grains are further refined, and the microstructure gradually transitions from the original Widmanstätten and basketweave structures to a more uniform laminar structure. Accordingly, the transformation of the microstructure leads to enhanced mechanical properties of the TC4 titanium alloy. Compared to the untreated as-deposited titanium alloy, the hardness of the FSP-processed samples significantly increases by 46.9 HV 1 on the horizontal plane and 33.8 HV 1 on the vertical plane. Additionally, the reduction in friction coefficient (from 0.47 to 0.41), a substantial decrease in wear mass (3.7 mg), and a slight improvement in the corrosion resistance of the titanium alloy collectively demonstrate the effectiveness of the FSP process in enhancing the performance of as-deposited TC4 titanium alloy. [Display omitted] • Laser Metal Deposition (LMD) and Friction Stir Processing (FSP) synergize to refine the microstructure of TC4 alloy. • FSP eliminates defects such as cracks and pores, enhancing the alloy's hardness, wear resistance, and corrosion resistance. • Microstructure evolution from columnar to equiaxed grains and bimodal structure by FSP enhances mechanical properties. • Electrochemical analysis confirms the improved corrosion resistance of TC4 alloy by FSP treatment. • FSP is a viable technique for performance enhancement of LMD-formed titanium alloys, broadening their industrial relevance. [ABSTRACT FROM AUTHOR]

In the aviation industry, fretting fatigue represents a significantly hazardous form of fatigue failure, thus warranting substantial research attention. A key area of focus lies in enhancing the fretting fatigue resistance of aluminium alloys. This study investigates the feasibility of using Friction Stir Processing (FSP) to enhance fretting fatigue lifetime. After FSP, large-size inclusions in the Base Material (BM) are shattered, clustered inclusions are dispersed, and the preferred orientation of inclusions is disrupted. Consequently, areas of stress concentration, damage concentration and merging of hazardous zones become less, and the peak values of stress, stress triaxiality, and damage are decreased with 6–10 %. Compared to BM, the results show that the fretting fatigue lifetime of Friction Stir Processed (FSPed) material is increased by 50.1 %. Hence, FSP could emerges as a highly promising surface treatment technique for enhancing fretting fatigue performance. [ABSTRACT FROM AUTHOR]

A novel step grooving approach is proposed for the reinforcement incorporation before FSP, enabling the creation of through-thickness composition gradient with a higher volume fraction of reinforcement near the surface and relatively lower volume fraction in the core by using a single step of FSP. The overall tensile strength of Al-GNP functionally graded composite (FGC) is increased by ∼52% compared to pure aluminium. The localized Young's modulus and yield strength of the core region is increased by ∼12% and ∼54% compared to the surface region of the fabricated composite, respectively. The maximum strain in the core region is also decreased by ∼38% depicting its higher stiffness over the surface region. Contrastingly, the microhardness of the surface region is increased by ∼18% compared to the core region of the fabricated composite. Thus, a combination of higher surface hardness and excellent core tensile strength is achieved with the proposed methodology. The bending of graphene interlayers leading to the mechanical exfoliation of GNP increased the load sharing capability of the Al/GNP interface. The load sharing through interface and coefficient of thermal expansion mismatch between Al and GNP are identified as the dominant strengthening mechanisms in the fabricated composite. [Display omitted] [ABSTRACT FROM AUTHOR]

Three different rotational speeds (800, 1000 and 1250 rpm) and traverse speeds of (0.42 mm/sec) at a constant taped pin have been employed to produce the stir zones generated from friction stir processing (FSP) of near eutectic Al- 14 wt.% Si alloy. The processed samples were thoroughly analyzed macroscopically and microscopically. The as-cast microstructure of eutectic (α Al+ Si) and primary Si were fragmented to produce spheroidization of small size of Si and deformed matrix. The stir zones showed an increase in hardness from around 45-50 Hv for as-cast to 40-65 depending on the variables applied. All the processed samples were characterized by advanced and retreated regions with large single piping defects formed mainly at the retreated region. High temperature spheroidization at 500 oC with two soaking times of 10 and 20 hrs was applied for the processed sample of 1000 rpm to investigate the effect of heat treatment on the silicon fragmentation and hardness. Growth and fragmentation of Si have taken place at soaking time of 10 hrs. At soaking time of 20 hrs noticeable microvoids and macrovoids were formed at the stir zones. Microhardness of both the advancing and the retreating regions decreased with increasing soaking time. [ABSTRACT FROM AUTHOR]

This paper presents a review of important aspects related to the Friction Stir Welding and Friction Stir Processing (FSW/FSP) concepts. The FSP, as a variation of the FSW, uses the same principle, but instead of the material joining, the FSP focuses on a surface modification aiming at improving surface properties of the substrate material. Thin surface composites can be made either by using grooves or drilled holes. FSP process parameters have been elaborated: axial force, rotational and traverse speed, tilt angle, insertion depth and tool geometry, as well as number of passes. Review of the used materials in fabrication of composites by using FSP is shortly presented. Effects of the FSP on mechanical properties have been discussed: effects on the microstructure, hardness and wear properties, tensile strength, and fracture and defects formation. FSP has evolved as an efficient method to modify surface structures, especially important for metallic materials that exposed to different harsh conditions, and further research will enable its wider use in industry. [ABSTRACT FROM AUTHOR]

Friction stir process (FSP) applications in producing surface composites have become the focus of researchers' attention in recent years. Axial load, tool rotation, feed rate, tool geometry, tool size and reinforcement material strategy are the main factors affecting the properties of surface composites (SC). In this study, Al5083–H111/SiC surface composites (SC) were produced in a single pass by friction stir process (FSP), and the effects of axial load and tool rotation speed on the microstructure, mechanical properties and wear behaviour of SCs were investigated. Different axial loads (6000, 8000 and 10000 N) and tool rotation speeds (560, 710 and 900 rpm) were used in the study. Optimum results from the tests performed were obtained in sample number N8, produced at an axial load of 8000 N and a rotation speed of 900 rpm. Specimen N8 showed a 38 % improvement in hardness and a 42 % improvement in wear tests performed under a 15 N load compared to the base metal. In the maximum tensile strength, the closest results to the base material were seen in sample N8 with 97 % performance. [Display omitted] • The effect of axial load on Al5083/SiC surface composites in the FSP technique was investigated. • A 1.4 and 1.7 times improvement in hardness and wear rate was achieved in SZ compared to BM, respectively. • A good interface between matrix and reinforcement was observed. • Compared to other parameters, it provided superior properties at 900 rpm rotational speed and 8000 N axial load values. [ABSTRACT FROM AUTHOR]