Friction Stir Processing Research Articles

High-efficient hybrid arc and friction stir additive manufacturing of high-performance Al-Cu-Mg-Ag-Zr alloy: Microstructural evolution and precipitation behaviors with Ω/L12 co-precipitates

Cost-effective and convenient additive manufacturing technologies are recognized as suitable alternatives for achieving lightweight aluminum alloy components with dense and defect-free parts toward high mechanical properties. Herein, a high-efficient hybrid arc and friction stir additive manufacturing (HAFS-AM) technique was employed to fabricate a high-performance Al-Cu-Mg-Ag-Zr alloy part. The AC pulsed tungsten inert gas (TIG) was utilized for the rapid pre-deposition of Al-Cu-Mg-Ag-Zr alloy with high efficiency. Friction stir processing contributed to eliminating pore defects and refining coarse microstructure in the pre-deposited arc layers, accounting for enhancing mechanical properties. During the HAFS-AM, the coarse θ phase with continuous network morphology was completely broken and gradually dissolved into the α-Al matrix. The addition of Zr element promoted the precipitation of coherent L12-Al3Zr inducing dislocation shearing behavior. The Mg and Ag additions accelerated the precipitation of semi-coherent plate-like Ω and σ phases, where a critical size (thickness and diameter) of precipitates existed for deciding the behaviors of dislocation shearing and dislocation looping. The ultimate tensile strength and elongation of the HAFS-AMed steady-state layer reached 262 MPa and 18.8 %, which were increased by 21 % and 96 % compared to that of the arc layer, respectively. The combined effect of arc and friction stir with high efficiency achieved high-performance manufactured components, expediting the future industry application of advanced additive manufacturing technology.

New Technique to Repair Keyhole of 2195 Al-Li Alloy Friction Stir Welding Joints.

Aiming at the repairing of keyhole defects after friction stir welding of complex structures, a new method combined with tungsten inert gas welding (TIG) and friction stir processing (FSP) was proposed. The results showed that the pre-filling wire of TIG can completely fill the volumetric keyhole. FSP can refine the coarse grain area into equiaxial grains due to dynamic recrystallization, while some pore defects are eliminated. The interface bonding quality is high. The microhardness of the repairing zone with FSP is significantly stronger than that of the untreated parts. Compared to direct TIG repairing, the introduction of FSP transformed the fracture from brittle fracture to ductile fracture, and the tensile strength of the joint was increased by 131.7%, realizing the high-quality repairing of keyhole defects in 2195 Al-Li alloy.

Study on the microstructure and mechanical properties of hot rolled nano-ZrB2/AA6016 aluminum matrix composites by friction stir processing

In this paper, in-situ ZrB2/AA6016 particle-reinforced aluminum matrix composites were prepared in molten A6016 aluminum alloy melt by KBF4-Al- K2ZrF6 reaction system. For the first time, this paper presents that after casting, the composites would be subjected to large strain hot rolling (LSHR) with 60 % undercutting and then friction stir processing (FSP) with a stirred probe speed of 1200 r/min and a traveling speed of 60 mm/min. To study the microstructure and mechanical properties of composites strengthened by large strain hot rolling combined with friction stir processing. The results show that the tensile strength of the base material is 140.1 MPa, the elongation is 46.3 %, the product of strength and elongation reaches 6.5 GPa%, and the average hardness is 43.4 HV; The tensile strength of LSHR+FSP nugget zone is 163.4 MPa, the elongation is 78.9 %, the product of strength and elongation reaches 12.9 GPa %, which is about 98.6 % higher than the base material, and the average hardness is 59.8 HV, which is about 37 % higher than the base material. SEM, EBSD, and TEM analyses showed that the average grain size is refined from 189.7 μm to 3.8 μm after LSHR+FSP. The ZrB2 particles are sufficiently fragmented, with a particle size of about 20 nm, and uniformly dispersed in the matrix. This study provides the theoretical and experimental basis for applying nanoscale ZrB2 particles reinforcing ultrafine crystalline aluminum matrix composites prepared by LSHR + FSP.

Effect of Friction Stir Process on Mechanical Properties and Bottom Section Ultimate Strength of Ship Steel

Effect of Friction Stir Process on Mechanical Properties and Bottom Section Ultimate Strength of Ship Steel

A Comprehensive Study of Friction Stir Processing Technique

Friction Stir Processing technique is a surface modification method that transforms heterogeneous microstructures into homogeneous ones, enhancing the mechanical properties of metal sheets. This single-step process, introduced by The Welding Institute (TWI) in 1991, offers advantages such as superior strength and formability, especially in aluminum alloys. FSP's simplicity, cost-effectiveness, and environmental friendliness make it preferable over traditional methods. Despite challenges in aerospace and transportation applications, FSP shows promise for forming lightweight alloys at room temperature. However, producing ultrafine grain sheet metals remains a challenge. Overall, FSP presents a viable solution for improving material properties and processing efficiency in various industrial applications. This study includes the literature review of research publications from different researchers to develop the understanding regarding friction stir processing technique.

Friction stir processing of AA6061-T6/graphene nanocomposites: Unraveling the influence of tool geometry, rotation, and advancing speed on microstructure and mechanical properties

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.

Experimental investigation on characterization of friction stir processed AZ31-based composite

Present study has been conducted to characterize the Mg alloy namely AZ31-based composite joined by Friction stir processing (FSP) technique. This study deals with the effect of single and double passes in FSP of AZ31 Mg alloy. The single pass run in FSP is followed at tool rotation speed (N) of 1000 to 1400 rpm. Also, the double pass run in FSP was followed at these speeds without using reinforcements. The feedstock particles namely SiC, Al2O3, Cr, and Si powders were used in fabrication process. The hardness, impact strength, and tensile strength characteristics were assessed in the stir region zone, and the results indicated significant improvement in these properties. The highest values of mechanical strength were seen in the FSPed area with N = 1000 rpm at a constant transverse speed (r) of 40 mm/min. Also, the tensile strength of the two passes FSPed plates is much higher than that of the single section without any reinforcement, as revealed in previous study also. The Scanning electron microscopy (SEM) analysis is done at two different magnifications for the Silicon carbide, Alumina, Chromium, and Silicon powder reinforced composites fabricated at speed of 1000 rpm. The microstructure shows that reinforced particles were uniform dispersed into FSPed region and agglomerated with Mg matrix. Si powder produces finer microstructure as compare to SiC, Al2O3, Cr. FSP decreases the grain size of processed material. Optical Microscopy results revealed that the reinforcement particle produced a homogenous microstructure and, a refined grain and equally dispersed in matrix material without split to the particle.

CoCrFeNiMoTi High-Entropy Alloy Reinforced Mg Matrix Composites Produced by Multi-pass Friction Stir Processing: Focus on Pin Geometry, Microstructure and Mechanical Properties

CoCrFeNiMoTi High-Entropy Alloy Reinforced Mg Matrix Composites Produced by Multi-pass Friction Stir Processing: Focus on Pin Geometry, Microstructure and Mechanical Properties

Sn/Graphite/Cu reinforced aluminum: An experimental study on fabrication of hybrid surface composite as journal bearing material by friction stir processing

Friction stir processing (FSP) is an energy-efficient and environmentally friendly technique that provides tailored manufacturing possibilities for surface composites in solid-state conditions. This study focuses on manufacturing solid lubricant-reinforced aluminum matrix surface composite (AMSC) through FSP, which can be used as a journal-bearing material. Composite fabrications are performed utilizing Sn, Cu, and graphite particles (hybrid powder) with four passes of FSP. The cross-sectional macro and microstructures of obtained surface composites are investigated via optical microscopy (OM) and scanning electron microscopy (SEM). The stir zone (SZ) chemistry is analyzed with energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The microhardness measurements show the effects of hybrid powder as reinforcement and FSP parameters on the mechanical features of the composite cross-sections. Wettability and tribological tests are also conducted to determine the surface properties of the fabricated composites. According to the findings, the wear rate is decreased by 8 % with the reduction of average CoF to 0.75, while a hardness increment is achieved over ∼35 % in manufactured surface composites compared to the base material. It is observed that the content and amount of the hybrid powder and FSP parameters employed can ensure the fabrication of desired characteristics compatible with the aim in surface composites.

Low-cost aluminum anodes for primary aluminum-air batteries prepared by friction stir processing

An economical Al-Mg-Si alloy, whose cost is only one-fifteenth of high-purity Al, was modified by friction stir processing towards low-cost high-performance aluminum anodes for primary aluminum-air batteries. The hydrogen evolution reaction was alleviated by the fragmentation of large precipitates and the dispersion of impurities, which was decreased to 0.257 mL/(cm2·min), and the power and energy densities increased by 36.4 % and 24.2 %, respectively. It indicated that this method provides novel opportunities to explore economical materials for primary Al-air batteries.

Development of machine learning regression models for the prediction of tensile strength of friction stir processed AA8090/SiC surface composites

Friction Stir Processing is a state-of-the-art technology for microstructure refinement, material property enhancement, and fabrication of surface composites. Machine learning approaches have garnered significant interest as prospective models for modeling various production systems. The present work aims to develop four machine learning models, namely linear regression, support vector regression, artificial neural network and extreme gradient boosting to predict the influence of FSP parameters such as tool rotational speed, tool traverse speed and groove width on ultimate tensile strength of friction stir processed AA8090/SiC surface composites. These models were developed through Python programming and the original dataset was divided into 80% for the training phase and 20% for the testing phase. The performance of the models was evaluated by root mean squared error, mean absolute error and R2. Based on the results and graphical visualization, it was observed that the XGBoost model outperformed other models with high accuracy in predicting UTS of AA8090/SiC surface composites.

Enhancing microstructural and mechanical properties of magnesium AZ31 matrix composites through friction stir processing incorporating silicon carbide, titanium carbide, and graphite particles

The present study focuses on investigating the effect of reinforcement on the microstructure and mechanical properties of friction-stir-processed magnesium hybrid composites. The groove width (0, 0.7, 1.1, 1.7, and 2.3 mm) of the Magnesium AZ31 plates was varied by varying the volume fractions (0, 5, 10, 15, and 20 vol%) of Silicon Carbide (SiC), Titanium Carbide (TiC), and Graphite (Gr) particle reinforcements in the hybrid composite. Single-pass processing was suspended using a cylindrical tool shoulder with a rotational speed, transverse velocity, and axial pressure of 1000 rpm, 30 mm min−1, and 6 kN, respectively. The optical micrograph clearly shows that a non-cluster zone (reinforcement particles are uniformly distributed without agglomeration) was identified in the processed region of the least concentrated composites. The results revealed that a peak tensile strength of 293.546 ± 5.12 MPa was attained for the combination of 10 vol% composites, and a Vickers hardness number of 86.53 HV was achieved for the 20 vol.% composites. The fracture surface morphology was analyzed using a Scanning Electron Microscope (SEM). The mode of tensile fractography was ductile for the least composite and transformed into a brittle mode of failure with the addition of reinforcements.

Optimization of friction stir processing to improve the mechanical properties of bone fixation plate inputs made of ZK60 magnesium alloy

Optimization of friction stir processing to improve the mechanical properties of bone fixation plate inputs made of ZK60 magnesium alloy

Tailoring the microstructure of a non-equiatomic Fe40Mn27Ni26Co5Cr2 high-entropy alloy via friction stir processing

High-entropy alloys (HEAs) with a face-centered cubic (FCC) lattice exhibit remarkable work-hardenability and high fracture toughness at cryogenic temperatures. However, in some non-equiatomic FCC HEAs, grain boundary melting defects may form during the homogenization process, which may lead to embrittlement of the grain boundaries. To address this issue, in this study, we propose the use of friction stir processing (FSP) to tailor the microstructure of a typical non-equiatomic Fe40Mn27Ni26Co5Cr2 HEA. After FSP, the mechanical properties of the non-equiatomic Fe40Mn27Ni26Co5Cr2 HEA were substantially improved. The study revealed that the improved mechanical properties could be attributed to the intense thermal-shear effect of FSP, which simultaneously eliminated grain boundary segregation and induced discontinuous dynamic recrystallization to refine grain size. Our findings not only shed light on understanding the embrittlement mechanism of homogenization treatment in non-equiatomic FCC HEAs, but also provide a useful route to improve the mechanical properties of FCC HEAs.

Overcoming Liquation Cracking in AA7075 Welds via Friction Stir Processing Pre-weld Treatment: A Microstructural Approach

Overcoming Liquation Cracking in AA7075 Welds via Friction Stir Processing Pre-weld Treatment: A Microstructural Approach

Study of anisotropy in polydispersed 2D micro and nano-composites by Elbow and K-Means clustering methods

A new two-dimensional polydisperse model for testing multiphase composites is developed. The verification of the model is carried out based on the microstructure of two composites obtained in the ex-situ and in-situ techniques produced in the Friction Stir Processing (Al–Si–Cu/SiCp) and the Self-propagating High temperature Synthesis (Al/nano-TiCp). The examined microstructure is considered on macro-, meso- and micro- levels. Besides the reinforcement phase distribution concentration, an anisotropy coefficient κ is calculated for every meso-cell. It is the cumulative vector parameter that characterizes the spatial two-point correlation of inclusions. In particular, κ determines the principal axes of the effective conductivity tensor over a meso-cell. The anisotropy spatial distribution ϰ(x) is introduced as the discrete function of values κ calculated over meso-cells centered at the point x. This new distribution ϰ(x) accumulates the geometrical information of the considered microstructure. A computational experiment is designed and carried out in order to study the influence of the reinforcement phase redistribution on the anisotropy. Therefore, it adequately describes the anisotropy of fields in composites modeling thermal and electric conductivity, diffusion, and elastic antiplane deformation. The results of the computational experiments are analyzed using the Elbow and K-Means clustering machine learning algorithm. The detailed analysis is carried out to divide the data set into up to 5 clusters. A research hypothesis concerning the criterion of isotropy of the distribution of reinforcing phase particles in the composite structure is formulated

Influence of Friction Stir Processing on the Hardness and Tribological Properties of Aluminium-Magnesium Alloys

Influence of Friction Stir Processing on the Hardness and Tribological Properties of Aluminium-Magnesium Alloys

Microstructure and strengthening mechanism of TIG welded joint of AZ31 alloy based on FSP technique

Magnesium alloys, renowned for their outstanding properties, present promising applications within the realm of advanced manufacturing. Addressing the challenges of coarse grains and inferior properties in the fusion welding of magnesium alloys, a novel strengthening approach for fusion-welded joints is proposed in this study. This method employs fine, uniform, and dense grains as the matrix, with particle-reinforced structures serving as the strengthening backbone. By utilizing powder feeding in conjunction with fusion welding and friction stir processing, ideal microstructures were successfully fabricated, and the mechanisms influencing grain morphology and joint properties were explored. Following the strengthening treatment, the grain size of the magnesium alloy molten weld was reduced from 193.5 μm to 15.9 μm, resulting in a grain refinement efficacy of 91.8 %. Concurrently, the tensile strength was augmented by 70.2 MPa, and the elongation experienced a 136 % enhancement. The grain morphology, eutectic phase structure, texture strength, precipitated phase type and dislocation distribution at each processing stage of the welded joint were observed. Research shows that nano-enhanced particles adhere to the eutectic structure of grain boundaries, effectively inhibiting the diffusion of solute elements and significantly reducing the dendrite growth rate. It is the main mechanism by which reinforced particles lead to grain refinement. Discontinuous recrystallization during FSP treatment leads to grain refinement, work hardening and enhanced pinning of particles at grain boundaries, which are the main reasons for the strength improvement.

The study of the effects of grain size, orientation and dislocation density on the HER performance of copper catalysts

Utilizing multi-pass friction stir processing with recirculating water cooling, pure copper plates were processed to successfully synthesize catalysts with distinct grain sizes. An exhaustive investigation into their intrinsic structures and properties was conducted. Analyses using X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) revealed that Cu-4.85 exhibits a preferred (111) crystallographic orientation along with a high dislocation density. Transmission electron microscopy (TEM) images clearly identified the types of dislocations present within Cu-4.85. Density functional theory (DFT) calculations further demonstrated that Cu-4.85 displays lower Gibbs free energy at the hollow site on the (111) plane, thereby facilitating the H* adsorption process. Collectively, this study delves into the cooperative influence of grain size, crystal orientation and dislocation density on the electrocatalytic hydrogen evolution (HER) performance. It was found that Cu-4.85 demonstrates exceptional HER activity, characterized by a reduced overpotential and a low Tafel slope. The study elucidates the mechanism of H atom adsorption in Cu-4.85 during the HER process, furnishing theoretical foundations for enhancing HER catalytic performance and offering significant theoretical and experimental insights for the design and fabrication of copper catalytic electrodes.

Optimization of friction stir process parameters for enhanced mechanical properties in surface-alloyed ZK60 magnesium with Tin (Sn): an RSM-ANN hybrid approach

ABSTRACT In the present work, the surface of the ZK60 Mg alloy was alloyed with tin (Sn), and the FSP process parameters have been optimized for the better mechanical properties by employing response surface methodology (RSM). Furthermore, RSM was combined with artificial neural networks (ANNs) to evaluate and compare the predictive capacity of both the models. FSP process parameters, namely, tool rotational speed (S), feed rate (F), number of passes (N), and weight percentage of Sn (W) were selected as influential parameters for optimization. The optimum conditions that were predicted by the RSM model to maximize the ultimate tensile strength (UTS) and % elongation (%EL) were a tool rotational speed of 2000 rpm, a feed rate of 0.39 mm/sec, 3 number of passes, and 8 wt.% of Sn which yields the maximum tensile strength of 217 MPa and the maximum %El of 26%.