Papers by Keyword: Friction Stir Processing

Abstract: Friction Stir Processing (FSP) is an advanced solid-state surface modification technique used to enhance the microstructural and mechanical behavior of metallic materials, particularly aluminum alloys. Recently, High-Entropy Alloys (HEAs) have emerged as promising reinforcement materials due to their high strength, thermal stability, and corrosion resistance. Although multiple studies have explored FSP with conventional reinforcements, the integration of HEAs into the stir zone remains limited. This study examines the influence of tool geometry, processing parameters, and reinforcement strategies in FSP while evaluating the feasibility of incorporating HEAs into aluminum matrices. The role of finite element analysis (FEA) in predicting temperature distribution, material flow, and stress evolution is also discussed. The study identifies research gaps and emphasizes the need for experimental validation of HEA-reinforced FSP systems to develop high-performance aluminum-based surface composites.

Abstract: In this study friction stir processing (FSP) was utilized to refine the microstructure of thick AZ31D magnesium (Mg) alloy, followed by evaluation of its microstructure and corrosion behavior in a NaCl environment. The application of a tapered threaded pin profile resulted in enhanced material mixing, significant grain refinement and reduced defect formation due to minimal heat input and minimized thermal gradients across the stir zone (SZ). The SZ, dominated by the pin profile, exhibited a fine, equiaxed, and uniform grain structure throughout its thickness the average grain size reduced from 13.8 µm to 5.19 µm after second pass of FSP confirmed through field-emission scanning election microscopy (FE-SEM) analysis. This structural refinement significantly enhanced the corrosion performance of the FSPed alloys, as compared to the base material (BM), demonstrated by electrochemical testing in 3.5% NaCl solution. The FSPed alloy surface showed uniform corrosion behavior, instead of intergranular corrosion with deep mud cracking patterns observed in the BM. This improved corrosion resistance was due to the uniformity of the produced microstructure via FSP, which reduced localised corrosion sites. These findings suggest that FSP is a promising technique for improving the durability of Mg alloys in corrosive environments, potentially benefiting applications in the automotive and aerospace industries.

Abstract: The concept of developing a bamboo-based Nylon 66 polymer matrix composite is a relatively novel and very new technical attempt through friction stir processing (FSP). This innovative approach can create a composite material that strengthen the mechanical properties of bamboo and the versatility of Nylon 66. However, successful implementation requires careful consideration of FSP process parameters such us tool rpm, traverse speed, tilt angle and tool design. Among the processing parameters, the tool rpm shows the significant role for severe plastic deformation and temperature generation which leads to the achieving excellent bond. Therefore, in this present study attempt has made to develop the polymer matrix composite (nylon 66 and bamboo powder) using FSW process at a variant rotational speed of 300,400 and 500 rpm with the constant traverse speed of 25 mm min^-1. The deformation behavior and the peak temperature evolved under the tool shoulder during the stirring motion is studied using COMSOL Multiphysics simulation. It is found that, the specimen processed with higher rpm (500rpm) shows the higher volumetric strain and the peak temperature and it is evident that with increasing rpm the higher amount of severe plastic deformation occurred. Initially the process parameters are optimized without bamboo powder on the nylon 66 plate of 6 mm thickness and found that the 500 rpm processed specimen shows the defect free. Prior to the actual FSP, the small keyways taken on the center of the nylon 66 plate in order to add the bamboo powders in it. Actual processing was done with bamboo powder after adding natural bamboo powder of size 50µm. The result reveals that, the bamboo powder has partially expelled out during the period of FSP. This complete study concedes that the processing parameters needs to be optimized and also bamboo added method need to be studied for the successful development of bamboo-based polymer matrix composite.

Abstract: Friction Stir Process (FSP) is considered one of the most convenient, effective, and environmental friendly manufacturing processes. In these processes, a tool involves a pin that blends the material around it and a shoulder that creates frictional heat. On the other hand, the pin mixes the soft material to refine the grain structure. This paper aims to investigate a thermal model using Altair to numerically simulate the temperature distribution profiles of 7075 Aluminum Alloy material using FSP. Using a novel technique called Smoothed-Particle Hydrodynamics (SPH), we extracted the temperature distribution in the Stir Zone (SZ) for 900 RPM, 1200 RPM, and 1500 RPM Tool Rotational Speed (TRS) with constant Tool Traverse Speed (TTS). The temperature results obtained are incremental with increasing TRS. As a result, the temperature achieved from 900 RPM to 1500 RPM has increased by 21.20%. In addition, the obtained temperature is almost 50% of the melting point. The material flow on both Advancing Side (AS) and Retreating Side (RS) shows the thorough material mixing. The SPH technique helps to investigate the proper material flow modeling by dividing the AS and RS nodes and it was observed that they have thoroughly been mixed near the FSP tool pin.

Abstract: Metal matrix composites (MMCs) are now one of the most significant groups of modern engineering materials as a result of the increased attention they have received in recent years. MMCs have recently been manufactured using a variety of technical specifications and techniques, with properties such as the ability to withstand thermal stability at the lowest possible cost, reduced weight and density, increased strength and toughness, and improved wear resistance. It is crucial to homogenize the distribution of the reinforcing phase during composite processing in order to generate particulate or fibrous solid microstructures, depending on the form of the reinforcing phase of the composite. This implies that new procedures must be employed to enhance the mechanical and microstructural properties of metal products. One of the answers to the above challenges is friction stir processing (FSP). FSP improves the surface quality, ductility, formability, strength, hardness, and fatigue life of metal alloys without altering the properties of metals in bulk. This study aims to review MMCs suitable for FSP-designed marine structures and identify knowledge gaps. According to the literature, MMCs are advanced materials capable of exhibiting microstructure, increased hardness, strength, excellent damping, wear, and reduced thermal expansion, making them suitable for a wide range of applications. Although FSP is recognized as a new secondary processing approach to enhance the microstructure and properties of MMCs, few studies have reported the production of MMCs suitable for marine applications. Therefore, this opens a large gap that needs to be filled and requires further investigation of MMCs development.

Abstract: This paper reports on the influence of material position towards the bending strength of the 4 pass AA1050/AA6082 and AA6082/AA1050 FSPed joints. FSW approach was utilized to create dissimilar joints using two dissimilar plates. After that, the created dissimilar joints were put through a multi-pass friction stir processing. The microstructural analysis results revealed that the 4P 6082/1050 joint had substantially finer grains than the 4P 1050/6082 joint. The 4P 1050/6082 joint yielded the highest ultimate tensile strength when compared to that of the 4P 6082/1050 joint. The Vickers microhardness of 1050/6082 FSPed joints was found to be increased towards the AA6082, while 6082/1050 FSPed joints decreased towards AA1050. The bending strength analysis showed that there was no obvious trend in flexural strength.

Abstract: Model research tests of plastic deformation, fragmentation and flow of aluminum alloy material of Al-Mg-Sc-Zr system under high loaded friction in pair with a steel counterbody of a complex shape and comparison of the obtained result with the structure formed by friction stir welding have been carried out. The conducted studies show that the structure formed by extrusion of the material from the friction zone and its compaction in the channel of the counterbody is, in general, close in structure to the structure formed by friction stir welding of similar material. The distinguishing features of the structure formed in the model experiments on friction include the introduction into the stirring zone of material with deformed large-crystal structure, increased grain size of the stirring zone, the presence of defects and differences in the geometry of the stirring zone.

Abstract: Friction stir processing (FSP), with tilted parent metal is a new process, which consists in the use of an inclined base plate with an angle α = 1 - 3 º related to the table of the FSP processing machine, by mounting a calibrated part under one end of the base plate. Two clamping plates are fixed with screws on the base plate, and a sheet (parent metal, PM) or a workpiece is placed between the base plate and the clamping plates. The processing tool has the same tilt angle with respect to the sheet to be processed. Said parts are components of the jig for the process described. The processing tool performs a movement with the speed v(x), correlated with a simultaneous movement with the speed v(z) = v(x) tg α. The correlation is achieved by means of a program developed for the processing machine. Due to the tilt, during the FSP process, the leading edge of the rotating tool shoulder progressively enters the PM, continuously, at the point where the shoulder penetration depth in the PM is minimal. On the multifunctional friction processing machine, MMPF type, the processing by the described process of an aluminium alloy sheet, with the sizes 300 mm x 200 mm x 4 mm was performed. A hardened C45 steel tool was used, having the following technical characteristics: shoulder diameter 14 mm, smooth frusto-conical pin with a large diameter of 2.5 mm, a small diameter of 2.0 mm, and a height of 1.5 mm. The parameters had the following values: tilt angle α = 2° 6'; pin penetration depth h = 1.60 - 1.85 mm; tool speed n = 1500 - 2000 rpm; speed v(x) = 1 - 2 mm / s; speed (software correlated) v(z) = 0.03672181 * (1 - 2) mm / s; the temperature of the sheet behind the tool t = 240 - 420 °C. The appearance of the processed sheet is appropriate. No imperfections are observed. The results are appropriate. The tilted PM brings the following advantages of the process: the mechanical stress to produce burrs and / or chips on the surface of the PM decreases; the way the FSP process is carried out is improved, by reducing gap moving and vibrations; the appearance and mechanical characteristics of the processed areas are improved; the quality level of the executed products rises; wear of processing tools is reduced; energy efficiency increases; the electricity consumption of the machine decreases; productivity increases.

Abstract: The results obtained by ISIM Timisoara to the development of the friction stir welding process (FSW) have supported the extension of the researches on some derived processes, including friction stir processing (FSP). The experimental programs (the researches) were developed within complex research projects, aspects regarding the principle of the process, modalities and techniques of application, experiments for specific applications, being approached. The paper presents good results obtained by friction stir processing of cast aluminum alloys and copper alloys. The optimal process conditions, optimal characteristics of the processing tools were defined. The complex characterization of the processed areas was done, the advantages of the process applying being presented, especially for the cast aluminum alloys: EN AW 4047, EN AW 5083 and EN AW 7021. The characteristics of the processed areas are compared with those of the base materials. The results obtained are a solid basis for substantiating of some specific industrial applications, especially in the automotive, aeronautical / aerospace fields.

Abstract: Considering the remarkable results obtained by using friction stir welding process (FSW), ISIM Timisoara has developed research programs for the knowledge and development of processing processes based on the FSW process principle.The paper presents a synthesis of the researches and the results obtained within some of research projects carried out by ISIM Timisoara, regarding possibilities of using some of processes derived from the FSW process, which has focused mainly on two directions (areas): surface engineering (materials surface processing) and joining by friction riveting. In the field of surfaces engineering, there are presented some results that represent own contributions of ISIM Timisoara, regarding: friction stir processing as well as coating with functional layers from lightweight alloys of steel substrates (by friction with consumable tool).Regarding friction riveting, two methods are presented: classic friction riveting, respectively friction riveting with hybrid effect (mechanical grip and friction welding).The paper shows very good results obtained to FSP processing (for cast aluminum alloys), to friction riveting with hybrid effect (for aluminum and copper alloys) and to friction riveting (for aluminum alloy), but also some limitations of these friction processing methods.Also in the paper are presented new research directions that are currently being addressed, respectively that will be addressed in the next period at ISIM Timisoara, regarding new variants of application of FSW welding.