Showing papers on "Friction stir processing published in 2014"
TL;DR: In this article, the basic principles of friction stir welding (FSW) are discussed, including terminology, material flow, joint configurations, tool design, materials, and defects, with an emphasis on recent advances in aerospace, automotive, and ship building.
393 citations
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15 Aug 2014
TL;DR: Friction stir welding as discussed by the authors is a well-studied process for friction-stir welding, where the process parameters, material flow and micro-structural evolution, tool features and role are modeled and simulated.
Abstract: Overview of friction stir welding and examples of adoptions highlights and issues- Fundamentals of the friction stir process process parameters, material flow and microstructural evolution, tool features and role- Modeling and simulation of microstructural evolution during FSW/P- Friction stir welding configurations and tool selection gaps and mismatches- FSW of aluminum alloys low strength alloys, tailor welded blanks and tool/process design to maximize productivity, high strength alloys and strategies to maximize joint efficiency- FSW of magnesium alloys- FSW of high temperature alloys issues with tool materials and examples of titanium alloys and steels- Friction stir processing overview of derivative processes and potential- Residual stresses and mitigation strategies
215 citations
TL;DR: Graphene/aluminum metal matrix composites (MMC) with enhanced thermal conductivity are fabricated by friction stir processing (FSP) and graphene reinforcement is applied in the form of a graphene oxide (GO)/water colloid for safer and simpler processing as mentioned in this paper.
Abstract: Graphene/aluminum metal matrix composites (MMC) with enhanced thermal conductivity are fabricated by friction stir processing (FSP). In fabrication of the MMC, graphene reinforcement is applied in the form of a graphene oxide (GO)/water colloid for safer and simpler processing. The result of Raman spectroscopy suggests that graphene reinforcements are successfully mixed into the aluminum matrix by FSP. The thermal conductivity of the graphene/aluminum MMC is measured to increase by more than 15% in comparison with that of the aluminum matrix. FSP and graphene reinforcement both improve the ductility of the fabricated MMC.
176 citations
TL;DR: In this paper, a net of holes were designed by drill on the surface of pure Cu sheet to improve distribution of reinforcing SiC particles, and the fine particles had a good distribution in the stir zone (SZ).
139 citations
TL;DR: In this paper, a CNT shortening model is proposed to describe the CNT length change with FSP passes, and the model indicates that the reciprocal of CNT lengths has a linear relationship with the duration of the mechanical effect, which was verified by the experimental results on various mechanical processes.
127 citations
TL;DR: In this article, a route combining powder metallurgy and subsequent friction stir processing was utilized to fabricate carbon nanotube reinforced Al (CNT/Al) and 6061Al composites.
112 citations
TL;DR: In vitro bioactivity studies by immersing the samples in supersaturated simulated body fluid (SBF 5×) indicate that the increased hydrophilicity and pronounced biomineralization are due to grain refinement and the presence of nHA in the composite respectively.
101 citations
TL;DR: In this paper, the effect of overlapping between consecutive passes of FSP was examined on the microstructure, microtexture, and mechanical properties of Al 6063, and the results showed that SHTA led to grain growth with an average grain size of 35μm.
97 citations
TL;DR: In this article, a hollow and pinless DFSP tool was designed to fabricate the surface composite on the AZ31 plate of rolling state, which was then pressed into the workpiece as the rotating tool advanced along it just like a planter.
96 citations
TL;DR: The immersion studies in super saturated simulated body fluid for 24 h suggest that the increased wettability due to fine grain structure and nHA particles present in the AZ31–nHA composite initiated heterogeneous nucleation which favored the early nucleation and growth of calcium-phosphate mineral phase.
Abstract: Friction stir processing (FSP) was successfully adopted to fabricate nano-hydroxyapatite (nHA) reinforced AZ31 magnesium alloy composite as well as to achieve fine grain structure. The combined effect of grain refinement and the presence of embedded nHA particles on enhancing the biomineralization and controlling the degradation of magnesium were studied. Grain refinement from 56 to ~4 and 2 μm was observed at the stir zones of FSP AZ31 and AZ31-nHA composite respectively. The immersion studies in super saturated simulated body fluid (SBF 5×) for 24 h suggest that the increased wettability due to fine grain structure and nHA particles present in the AZ31-nHA composite initiated heterogeneous nucleation which favored the early nucleation and growth of calcium-phosphate mineral phase. The nHA particles as nucleation sites initiated rapid biomineralization in the composite. After 72 h of immersion the degradation due to localized pitting was observed to be reduced by enhanced biomineralization in both the FSPed AZ31 and the composite. Also, best corrosion behavior was observed for the composite before and after immersion test. MTT assay using rat skeletal muscle (L6) cells showed negligible toxicity for all the processed and unprocessed samples. However, cell adhesion was observed to be more on the composite due to the small grain size and incorporated nHA.
90 citations
25 Apr 2014-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the effects of nano-Al 2 O 3 particle addition on the evolution of the grain structure and mechanical behaviour of a friction-stir-processed Al matrix were studied and discussed in detail.
Abstract: The fabrication of nano-composites is quite challenging because the uniform dispersion of nano-sized reinforcements in metallic substrates is difficult to achieve using powder metallurgy or liquid processing methods. In the present study, Al-based nano-composites reinforced with Al 2 O 3 particles have been successfully fabricated using friction stir processing. The effects nano-Al 2 O 3 particle addition on the evolution of the grain structure and mechanical behaviour of a friction-stir-processed Al matrix were studied and discussed in detail. It was revealed that the pinning effect of Al 2 O 3 particles retarded grain growth following recrystallisation during FSP and led to a more pronounced reduction in grain size. Significant increases in the microhardness and tensile strength relative to Al under the same conditions were obtained by adding Al 2 O 3 particles. A microstructural examination suggested that the voids initiated from the Al/Al 2 O 3 interfaces during testing of the tensile strength of the nano-composites.
TL;DR: In this paper, the cavitation erosion behavior, before and after FSP, was evaluated in terms of incubation time, cumulative mass loss and mean depth of erosion in commercial AISI 316L plates with the initial grain size of 14.8 m.
TL;DR: In this paper, friction stir processing was used to prepare NiTip reinforced 6061Al bulk composites with the aim to avoid deleterious Al-NiTi interface reaction occurred in cast and powder metallurgy processes.
27 May 2014-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the results of pole figures evaluation obtained by electron back scattered diffraction studies revealed that the random orientation of initial annealed sheet was changed to components near to shear and silver texture in the friction stir processed alloy without and with pre-placed powder, respectively.
Abstract: Aluminum matrix nanocomposites were fabricated by friction stir processing of Al–Mg alloy sheets with pre-placed TiO 2 nanoparticles at a concentration of 2 to 6 vol%. Microstructural studies showed that solid state reactions between the metal matrix and TiO 2 particles caused in situ formation of MgO and Al 3 Ti nanophases with an average size ~50 nm. These nanophases were homogenously distributed in an ultra-fine grain structure (0.2–2 µm) of the base metal. The results of pole figures evaluation obtained by electron back scattered diffraction studies revealed that the random orientation of initial annealed sheet was changed to components near to shear and silver texture in the friction stir processed alloy without and with pre-placed powder, respectively. The concentration of TiO 2 particles affected the preferred texture orientation as the ceramic inclusion restricted the severe plastic deformation and dynamic recrystalization of the metal matrix. Hardness and tensile yield strength of the Al–Mg alloy sheet were also significantly improved by employing friction stir processing in the presence of TiO 2 nanoparticles (up to ~3.1 vol%). Fractographic studies showed a mixture of ductile–brittle fracture modes with an increase in the content of catastrophic manner at higher TiO 2 fractions.
TL;DR: In this paper, the ability of friction stir processing (FSP) in incorporating yttria particles into copper to produce an oxide dispersion strengthened material was shown for the first time.
TL;DR: In this paper, a copper-based composite was fabricated by TiC reinforcement via friction stir processing, which produced a fine grain microstructure with a homogeneous distribution of particles on the surface.
TL;DR: In this article, a multistep friction stir processing (FSP) was used to produce functionally-graded bulk Al-SiC nanocomposites by a novel multi-stage FSP for the first time.
TL;DR: In this article, the effect of FSP parameters on the properties of copper surface composites such as the area of the surface composite, microhardness and wear rate was investigated. But the authors did not consider the micro-structural characterization of the prepared copper surfaces composites.
TL;DR: In this article, MIG welded butt joints, performed in 5083-H111 aluminium alloy plates with 6mm thickness, were post-processed by friction stir processing.
10 Jan 2014-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the microstructure-mechanical property correlations for a Mg-4Y-3RE (WE43) alloy were reported for both as-received and friction stir (FS) processing.
Abstract: This paper reports microstructure–mechanical property correlations for a Mg–4Y–3RE (WE43) alloy. Friction stir (FS) processing was employed to modify the microstructure of hot-rolled (as-received) WE43 alloy. The grain size decreased from 10 to 300 µm in as-received condition to an average of 3.1±0.4 µm in FS processed condition. The alloy in AR condition contained globular, acicular, and rectangular (cuboidal) shaped precipitates located at twin boundaries, grain boundaries, and intragranular regions, along with fine scale honeycomb network of intragranular β1 precipitates. A very good combination of strength and ductility was observed for the alloy tested in FS processed condition. Detailed fractography was done to differentiate mode of fracture between as-received and FS processed conditions. Based on Schmid factor analysis, it was concluded that basal slip system controlled the yielding of the material in both the conditions. An empirical relationship was developed between work hardening rate and ductility. This can be applied to microstructural design of magnesium alloys used for applications where high uniform ductility is needed.
TL;DR: Transmission electron microscopy (TEM) examinations confirm that grain refinement is attributed to continuous dynamic recrystallization both for NFSP and SFSP.
Abstract: Hot-rolled AZ31 (Mg-2.57Al-0.84Zn-0.32Mn, in mass percentage) magnesium alloy is subjected to friction stir processing in air (normal friction stir processing, NFSP) and under water (submerged friction stir processing, SFSP). Thermal history of the two FSP procedures is measured, and its effect on microstructures and mechanical properties of the experimental materials is investigated. Compared with NFSP, the peak temperature during SFSP is lower and the duration time at a high temperature is shorter due to the enhanced cooling effect of water. Consequently, SFSP results in further grain refinement, and the average grain size of the NFSP and SFSP specimens in the stir zone (SZ) are 2.9 μm and 1.3 μm, respectively. Transmission electron microscopy (TEM) examinations confirm that grain refinement is attributed to continuous dynamic recrystallization both for NFSP and SFSP. The average Vickers hardness in the SZ of the NFSP and SFSP AZ31 magnesium alloy are 76 HV and 87 HV. Furthermore, the ultimate tensile strength and the elongation of the SFSP specimen increase from 191 MPa and 31.3% in the NFSP specimen to 210 MPa and 50.5%, respectively. Both the NFSP and SFSP alloys fail through ductile fracture, but the dimples are much more obvious in the SFSP alloy.
01 Jan 2014
TL;DR: The microstructure of alloys affects the mechanical and physical properties of processed materials and joints as mentioned in this paper, therefore studying micro-structure evolution during friction stir welding/processing (FSW/FSP) of metals and their alloys is necessary.
Abstract: Friction stir welding/processing (FSW/FSP) of metals and their alloys has been investigated widely in recent years. The microstructure of alloys affects the mechanical and physical properties of processed materials and joints, therefore studying microstructure evolution during FSW/FSP of alloys is necessary. Recent investigations show that dynamic restoration phenomenon can occur due to the coexistance of strain and heat, during FSW. Also, some investigators believe that static restoration phenomena can occur. The type of restoration phenomena depend on material properties and procedure, whose management can control the microstructure of joints or processed metals, and hence their mechanical properties. In this chapter, the microstructural concepts including different microstructural zones, types of microstructural studies and different restoration phenomena are described. Then, microstructural evolution during FSW/FSP of different metals and alloys is discussed. Moreover, some illustrative examples are added to the end of each section.
TL;DR: In this paper, a new approach utilizing high-velocity oxy-fuel spraying and friction stir processing (FSP) was used to characterize the surface composites and the results indicated that the presence of Al2O3 in matrix can improve the mechanical properties of specimens.
Abstract: Surface A356 aluminum alloy matrix composites containing micro and nanosized Al2O3 are prepared by a new approach utilizing high-velocity oxy-fuel spraying and friction stir processing (FSP). Optical and scanning electron microscopy, microhardness, and wear tests were used to characterize the surface composites. Results indicated that, the presence of Al2O3 in matrix can improve the mechanical properties of specimens. The microhardness of surface composites containing micro and nanosized Al2O3 were 89.8 ± 2.6 HV and 109.7 ± 2.5 HV, respectively, which were higher than those for the as-received (79.6 ± 1.1 HV) and the FSPed A356-T6 with no alumina powder (66.8 ± 0.9 HV). Surface composites revealed low friction coefficients and wear rates, which were significantly lower than those obtained for substrate. The wear mass losses of the as-received, the FSPed, and surface micro and nanocomposite specimens after 500-m sliding distance were 50.5, 55.6, 31, and 17.2 mg, respectively. Scanning electron microscopy tests revealed different wear mechanisms on the surface of the wear test specimens.
TL;DR: In this paper, the UFG microstructure of Al-30Si alloy formed by friction stir processing (FSP) was correlated with its corrosion property. And the correlation of grain and silicon particle size on corrosion properties reveals Hall-Petch type relationship.
TL;DR: In this paper, the FSP was applied on metal inert gas (MIG) T-fillet welds performed in 6082-T651 aluminium alloy plates of 6mm thickness and the potential benefits were studied through microstructural analysis, hardness measurements, tensile strength and fatigue testing.
TL;DR: In this paper, a defect-free FSP method was employed to the surface modification of Ti-6Al-4V alloy applying different processing parameters, and microstructures of β-regions with acicular-α and GB-α, or needle-typed Martensite-α′ were obtained.
Abstract: The friction-stir processing (FSP) method was employed to the surface modification of Ti–6Al–4V alloy applying different processing parameters. The defect-free friction-stir processed surface layers with ~ 2.5 mm thickness, with final microstructures of β-regions with acicular-α and GB-α, or Martensite-α′ phase, were obtainable. The FSP processing thermal cycles, macro/micro-structures, phase evolutions, microhardness measurements, and dry-sliding wear performance of the processed surface layers were investigated. Considering to the basic laws of Ti–6Al–4V microstructure evolutions during the FSP procedures, the relations between processing parameters and produced microstructure characteristics were further elucidated. It was found that a relatively lower processing peak temperature and a fast enough cooling rate benefited the formation of the fine β-regions with ultra-refined acicular-α phase and/or even needle-typed Martensite-α′. The microstructures favored the improvement of hardness and wear performance of the processed surface layers, in comparison with those properties of the base material.
TL;DR: In this article, the authors reported microstructure and mechanical properties of the in-situ TiB2/Al-Mg-Si composites processed by friction stir processing (FSP).
TL;DR: In this article, the effect of different shoulder diameters to pin diameter (D/d ) ratio on the tensile properties and hardness of the friction stir processed material were evaluated and correlated with the macro and microstructure signatures.
TL;DR: In this article, the authors used in situ casting technique and applying friction stir processing (FSP) to enhance the distribution and morphology of Al 3 Ti and Al 3 Zr particles.
TL;DR: In this paper, the fabrication of Cu/WC composites by applying the 1-, 2-, and 4-pass friction stir processing was the main aim of present investigation, and the results indicated that the composites fabricated by this method had a good quality.
Abstract: The fabrication of Cu/WC composites by applying the 1-, 2-, and 4-pass friction stir processing was the main aim of present investigation. The results indicated that the composites fabricated by this method had a good quality. Increasing the pass numbers was also used to improve the dispersion of WC particles and consequently to intensify the mechanical properties of composite layers. The microstructural, mechanical, and thermophysical properties of the composites were used to confirm this claim. The grain size in these composites shows the promising reduction to the 1.2 μm in 4-pass friction stir processed one, and microhardness values reach to a considerable amount up to two times more than the pure copper. Wear rate and friction coefficient evaluation of the composites in different sliding rates demonstrated the composites resistance against weight loss and high reliability of the 4-pass friction stir processed composites in higher wear distances compared to that of fabricated by 1-pass. Moreover, the thermal expansions of the composites were examined up to 500 °C which is indicative of the composites stability in higher temperatures.