Papers by Keyword: FSP

Abstract: Mg-Al-Zn alloy, an Mg alloy having Al and Zn as the major constituents, is exceptionally lightweight and has potential to become an essential component of modern engineering applications and healthcare systems. This paper presents valuable insights to the friction stir processing (FSP) applied to Mg-Al-Zn alloy in dry conditions. FSP induced extreme plastic deformation in the metal alloy which causes substantial microstructural alterations. These changes were investigated using optical microscope. Microstructural evaluation of FSP-processed zone indicated that average grain diameter of the FSP-processed zone increased in proportion to tool rotating speed. This is attributed to the frictional zone's degree of plastic deformation. In alignment with results obtained from optical microscopy, morphological study conducted using scanning electron microscope (SEM) also demonstrated the synthesis of refined grains. In addition, the study includes evaluation of the FSP-processed alloy's micro-hardness and tensile characteristics in contrast to the base (unprocessed) alloy.

Abstract: The magnesium is selected for the future implants material due to its excellent biocompatibility behavior. The biodegradable and biocompatible nature of Mg and its alloy make it prime choice for the development of bio-implants. The mechanical properties of Mg are similar to natural human bone therefore it can be used for temporary implantation for supporting a fracture bone. The rapid biodegradation of pure Mg before the healing time, raise the requirement to develop a metal matrix composites of Mg. The prominent technique of MMC fabrication is friction stir processing (FSP). The FSP is widely used for fabrication of surface composites and also used for grain structure refining and strengthening. The current article reviewed the various surface composites of Mg developed by FSP for alteration of biodegradation and mechanical properties. .

Abstract: Friction stir processing (FSP) is a thermos-mechanical process for modifying the microstructural and material properties of metals. FSP also can be used for mechanical alloying and producing metal matrix composites. Due to creation of longitudinal cracks and tunneling cavities throughout the processing path, FSP of AZ91 is difficult and also sensitive to processing temperature. In this study, the effect of processing parameters such as the traverse and rotational speeds and the dimension of the tool pin on the temperature history experienced by material were investigated. Additionally, a minimum temperature required to produce a defect-free specimen was presented.

Abstract: The cast Al-Zn-Mg 7000 alloy has become one of the most potential structural materials in many engineering fields such as aircraft body, automotive casting due to their high strength to weight ratio, strong age hardening ability, competitive weight savings, attractive mechanical properties and improvement of thermal properties. The cast aluminium alloy has been modified of surface layer through a solid-state technique is called friction stir process (FSP). But basic principle has been followed by friction stir welding (FSW). This process can be used to locally refine microstructures and eliminate casting defects in selected locations, where mechanical properties improvements can enhance component performance and service life. However, some specified process parameters have adopted during experimental works. Those parameters are tool rotation speed (720 rpm), plate traverse speed (80 mm/min), axial force (15 kN), and tool design (i.e., pin height 3.5 mm and pin diameter 3.0 mm), respectively. The main mechanism behind this process likely to axial force and frictional force acting between the tool shoulder and workpiece results in intense heat generation and plastically soften the process material. The specified ratio of rotational speed (720 rpm) to traverse speed (80 mm/min) is considered 9 as low heat input during FSP and its entails low Zn vaporization problem results as higher fracture toughness of aluminium alloy. It is well known that the stirred zone (SZ) consists of refine equiaxed grains produced due to dynamic recrystallization. FSP has been proven to innovatively enhancing of various properties such as formability, hardness and fracture toughness (32.60 MPa√m). The hardness and fracture toughness of double passes AC+FSP aluminium alloy had been investigated by performing Vicker’s hardness measurement and fracture toughness (K_IC)(ASTM E-399 standard) tests. Detailed observations with optical microscopy, Vicker’s hardness measurement, SEM, TEM, and DTA analysis have conducted to analyse microstructure and fracture surfaces of double passes FSP aluminium alloy.

Abstract: This paper describes utilization of friction-stir forming (FSF) to generate a single wall on an aluminum alloy plate. The proposed process is as follows. The authors placed a material plate on a die having a variable-width groove and conducted friction stirring on its back surface. The material filled the cavity due to high pressure and heat caused by friction stirring. This process can be applied to generate thermal plate-fins and rib structures. The present study investigates the forming conditions and the corresponding results including the height limit of walls to obtain reference data for applications. In the experiment, a 3mm-thick JIS A5083P-O aluminum plate was utilized as the substrate. With a grove of less than 0.2mm-width, the wall was difficult to generate. The maxim height of the 0.2mm-thick wall formed by FSF was 2.8mm, and its aspect ratio was 14, which was difficult to form using conventional forging. Overall, the relationship between groove width of the die cavity and aspect ratio of maximum wall height to wall thickness followed the fractional curvature. This results implies that the deformable material volume generated by friction stirring is a key factor for wall height.

Abstract: This paper reports observation of material flow in friction-stir forming of aluminum alloy gear racks. Friction-stir forming was newly developed by Nishihara and is dedicated for material forming. In the process, a material plate is placed on the die and friction stirring is conducted on its back surface. The material deforms due to high pressure and heat caused by the friction-stir process and deforms precisely to the shape of the die. The process has mainly been studied for microforming and mechanical jointing; however it was successfully utilized for net-shape forming of A5083 aluminum alloy gear racks. The authors observed the appearance of products, change of mark-off lines on its surface, and deformation of its longitudinal cross section by photo-processing. In addition, we evaluated the distribution of hardness in transverse cross sections of a product tooth. As a result, it was observed that the material did not flow in the transverse direction of the cavity of the gear-rack die, though more material filled at the retreating side than at the advancing side. The material filled the tooth-cavity mostly before passage of the tool probe over the tooth.

Abstract: This paper reports friction-stir forming (FSF) of cylindrical pin embossments on JIS A5083 aluminum alloy medium gauge plate. A substrate material was put on an emboss die and conducted friction stirring on its back surface. The die has 1mm diameter and 0.5mm deep fine holes at 1.5mm pitch on its top, and the material successfully filled them due to high pressure and heat caused by friction stirring. Three tools having different shoulder diameter were utilized to investigate the deformable area with a single pass. As a consequence, faster spindle speed, slower tool feed rate, and larger tool shoulder contribute to a wider range of completely formed pins. Extrusion of the material to the die cavity seemed to be mostly limited under the area of the shoulder. The ratios of the band width of the complete pins to the shoulder diameter were increased with the larger diameter of the shoulder of the FSF tool. Therefore, a larger shoulder was more effective for wide-range embossing with a single pass. In addition, we evaluated the shape of formed pins with a non-contact 3D measurement system. Accuracy of the height of the completely formed pins was within ±0.013mm, which was comparable with machining.

Abstract: SiC₂ nanoparticles to aluminum alloy surface performance by the friction stir processing (FSP) was studied in this paper, the results showed that the SiC₂ nanoparticles to aluminum alloy surface performance by the FSP can improve the microhardness of the aluminum alloy surface, which further showed that by the method of modification aluminum alloy surface had the resistance performances of the wear and corrosion. At the same time, by the sample microstructure pictures can see, when the tool rotation speed was 1000 r/min and the welding speed was 110 mm/min, the obtained grains were tiny and the distribution of SiC₂ nanoparticles was the most uniform. When the tool rotation speed was 1000 r/min and the welding speed was 110 mm/min, the obtained grains were coarse and the distribution of SiC₂ nanoparticles was the most uneven. This showed that in FSP the main factor of generated higher friction heat was the tool of rotational speed, this was the main factors to ensure grain happen recrystallization. The fastest dissipation heat of the factor was the welding speed, this was the main factor of fine grain.

Abstract: The study was carried out to understand the effect of inhomogeneous microstructure on thickness variation in superplastically formed bulge. Friction stir processing was performed at rotational and traverse speeds of 720rpm and 155mm/min respectively on a 6mm sheet maintaining 50% overlap on the retreating side. Different probe dimensions were selected to obtain different proportions of fine grained stir zone in thickness direction. The proportions of the fine grained stir zone were 25%, 50%, 72% and, 100%. The sheets containing inhomogeneous microstructure were subjected to superplastic bulge forming under constant gas pressure up to a bulge height of 23.5mm. The sheet which was processed with 72% fine grains showed lower thickness variation from edge to apex and the bulge shape in this condition was close to the ideal spherical profile.

Abstract: In this investigation, copper (Cu) based surface composites reinforced with silicon carbide (SiC) particles were fabricated using friction stir processing (FSP) route. FSP was carried out considering three-factor three-level Box-Behnken design to study the effects of process parameters on peak temperature and hardness of Cu/SiC_p surface composites. Microstructural evaluation using optical microscope (OM) revealed that SiC_p were uniformly distributed and well – bonded with copper matrix at an adequate heat input conditions. The microhardness of the surface composites were remarkably enhanced than that of base metal. Regression models have been developed for predicting peak temperature and microhardness of processed surface composites and the same were in good agreement with experimental results.