Improving Erosion Resistance of Hydroturbine Steel Using Friction Stir Processing

In the present work, the slurry erosion behavior of friction stir processed (FSPed) hydroturbine steel (CA6NM) was investigated. For comparison, the erosion performance of unprocessed CA6NM steel was evaluated under similar conditions. Friction stir processing (FSP) is a microstructural refinement tool which is useful in enhancing the bulk and surface properties of materials. An in-depth characterization of both steels was done using an optical microscope (OM), a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS), the electron backscatter diffraction (EBSD) technique, and micro- and nano-indentation techniques. The FSP of the steel helped in reducing the erosion rates by 50% to 60%, depending upon the impingement angle. The improved performance of the FSPed steel in comparison to unprocessed steel was attributed to microstructural refinement, which increased the hardness and yield strength. At an oblique impingement angle, plowing, along with microcutting, was observed to be the dominant erosion mechanism. At a normal impingement angle, the material removal process was controlled by the platelet mechanism of erosion. A modified form of the mathematical model for predicting the erosion rates of the ductile materials, proposed by authors earlier, was also presented. This modified model based upon the theory of plasticity was able to predict the erosion rates with an accuracy of ±20%.

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Microstructure and Mechanical Properties of 34CrNiMo6 Steel Repaired by Friction Stir Processing

Materials ◽

10.3390/ma12020279 ◽

2019 ◽

Vol 12 (2) ◽

pp. 279 ◽

Cited By ~ 2

Author(s):

Zhongwen Wu ◽

Chunping Huang ◽

Fencheng Liu ◽

Chun Xia ◽

Liming Ke

Keyword(s):

Mechanical Properties ◽

Friction Stir Processing ◽

Steel Structures ◽

Optical Microscope ◽

Filling Material ◽

Welding Wire ◽

Friction Stir ◽

Filling Materials ◽

Microstructure And Mechanical Properties ◽

34Crnimo6 Steel

Repairing damaged parts using proper repairing methods has become an important means to reduce manufacturing and operational costs and prolong the service life of 34CrNiMo6 steel structures. In the conventional fusion repairing method, welding wire and powder are often used as filling materials. Filling materials are often expensive or difficult to find. Some metallurgical issues (such as solidification crack, higher distortion) were also found with these methods. At the same time, most of the equipment that requires welding wire and powder is expensive. In this study, a new method based on friction stir processing (FSP) was successfully employed to repair 34CrNiMo6 steel, using a block as filling material. Filling blocks are much cheaper than conventional fusion repair consumables. As a result of solid-state repair, this method can also avoid the metallurgical issues of fusion repair. The microstructure and mechanical properties of the repaired samples were investigated using OM (Optical Microscope), SEM, EDS (Energy Dispersive Spectroscopy), XRD, and a Vickers hardness electronic universal tensile tester. The results showed that 34CrNiMo6 steel was successfully repaired by this method, with no defect. Tensile tests showed that the maximum ultimate strength (UTS) was 900 MPa and could reach 91.8% of that of the substrate. The fracture mode of the tensile samples was ductile/brittle mixed fracture. Hence, the repairing method based on FSP appears to be a promising method for repairing castings.

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Effect of Friction Stir Processing Parameters on the Properties of AA7075-T73/Al2O3 Surface Metal Matrix Composite

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1002.140 ◽

2020 ◽

Vol 1002 ◽

pp. 140-150

Author(s):

Ali H. Al-Helli ◽

Ahmed R. Alhamaoy ◽

Ayad Murad Takhakh

Keyword(s):

Friction Stir Processing ◽

Particle Distribution ◽

Surface Hardness ◽

Base Material ◽

Processing Parameters ◽

Optical Microscope ◽

Friction Stir ◽

Surface Composite ◽

Surface Metal ◽

Number Of Passes

Friction Stir Processing (FSP) technology was wielded to output the Al7075/ Al2O3 surface composite. The effects parameters of processing method on particle distribution have been studied. The microstructure and mechanical characteristics of the samples were examined using the optical microscope, SEM and hardness examination. Acquired consequences, showed that Al2O3 particles were in a good interior distribution inside the basement. This technique produced excellent bonding between the surface composite and the base material. On other hand the surface hardness was increased about 25% as compared with the substrate. In addition, grain matrix refinement and enhanced particle distribution were obtained after each FSP pass. Also the dispersion of Al2O3 particles in the stirred area became more homogeneous and the average hardness improved by increasing the number of passes.

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Microstructure Evolution and Mechanical Property Characterization of 6063 Aluminum Alloy Tubes Processed with Friction Stir Back Extrusion

JOM ◽

10.1007/s11837-019-03852-7 ◽

2019 ◽

Vol 71 (12) ◽

pp. 4436-4444

Author(s):

Suhong Zhang ◽

Alan Frederick ◽

Yiyu Wang ◽

Mike Eller ◽

Paul McGinn ◽

...

Keyword(s):

Aluminum Alloy ◽

Microstructure Evolution ◽

Electron Backscatter Diffraction ◽

Deformation Gradient ◽

Optical Microscope ◽

Grain Structure ◽

Frictional Heat ◽

Friction Stir ◽

Metal Extrusion ◽

Backscatter Diffraction

Abstract Friction stir back extrusion (FSBE) is a technique for lightweight metal extrusion. The frictional heat and severe plastic deformation of the process generate an equiaxed refined grain structure because of dynamic recrystallization. Previous studies proved that the fabrication of tube and wire structures is feasible. In this work, hollow cylindrical billets of 6063-T6 aluminum alloy were used as starting material. A relatively low extrusion ratio allows for a temperature and deformation gradient through the tube wall thickness to elucidate the effect of heat and temperature on the microstructure evolution during FSBE. The force and temperature were recorded during the processes. The microstructures of the extruded tubes were characterized using an optical microscope, energy-dispersive x-ray spectroscopy, electron backscatter diffraction, and hardness testing. The process reduced the grain size from 58.2 μm to 20.6 μm at the inner wall. The microhardness of the alloy was reduced from 100 to 60–75 HV because of the process thermal cycle.

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Effects of Various Cooling Techniques on Grain Refinement of Aluminum 7075-T651 During Friction Stir Processing

Volume 14: Emerging Technologies; Materials: Genetics to Structures; Safety Engineering and Risk Analysis ◽

10.1115/imece2016-66161 ◽

2016 ◽

Cited By ~ 4

Author(s):

Vivek V. Patel ◽

Vishvesh J. Badheka ◽

Samarth R. Zala ◽

Sagar R. Patel ◽

Utsav D. Patel ◽

...

Keyword(s):

Grain Size ◽

Friction Stir Processing ◽

Weight Ratio ◽

Optical Microscope ◽

Process Temperature ◽

Friction Stir ◽

Fine Grain ◽

State Process ◽

Structural Applications ◽

Aluminum 7075

Aluminum 7075 alloy (AA 7075) is one of the prime materials used in the aviation and automotive industry because of its high strength to weight ratio, good amount of fatigue strength and high machinability. Friction stir processing (FSP) is one of the emerging solid state process that refines the microstructure and hence improved mechanical properties are obtained. The process temperature during FSP affects the resulting microstructure so the attempt for reducing the process temperature can result into reduction in the grain size. The fine grain size microstructure delivers high percentage of elongation which reduces the number of joints and welds in the critical structural applications. So, by implementing coolants such as water and carbon dioxide (CO2) during this process had hindered the grain growth and very fine grained microstructure was obtained. The fine grain microstructure offers higher elongation and hardness as deformation starts from the grain boundaries. In this experimental investigation we intended to keep the temperature generation during the process as low as possible by keeping the process parameters of 765 rpm, 31.5 mm/min fees rate and 20 tilt of the tool (optimized for tapered threaded cylindrical pin tool) constant. All the samples were examined by metallographic characterization using optical microscope. The grain size measurements for all three FSP samples were carried out. Water and CO2 cooled FSP samples reported much more fine grain as compared to naturally cooled sample because of the less heat input during the process.

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Wear and Mechanical Properties of Aluminum Alloy Based Hybrid Composites [(SiC+Gr) and (SiC+Al2O3)] Fabricated by Friction Stir Processing

Volume 2A: Advanced Manufacturing ◽

10.1115/imece2013-64734 ◽

2013 ◽

Author(s):

A. Kumar ◽

A. Devaraju ◽

B. Kotiveerachari

Keyword(s):

Mechanical Properties ◽

Aluminum Alloy ◽

Friction Stir Processing ◽

Rotational Speed ◽

Solid Lubricant ◽

Hybrid Composites ◽

Optical Microscope ◽

High Wear Resistance ◽

Nugget Zone ◽

Friction Stir

In this investigation, the influence of tool rotational speed on wear and mechanical properties of Aluminum alloy based surface hybrid composites fabricated via Friction stir processing (FSP) was studied. The fabricated surface hybrid composites have been examined by optical microscope for dispersion of reinforcement particles. Microstructures of all the surface hybrid composites revealed that the reinforcement particles (SiC, Gr and Al2O3) are uniformly dispersed in the nugget zone. It is observed that the microhardness is decreased with increasing the rotational speed and exhibited higher microhardness value in Al-SiC/Al2O3 surface hybrid composite at a rotational speed of 900 rpm, due to presence and pining effect of hard SiC and Al2O3 particles. It is also observed that high wear resistance exhibited in the Al-SiC/Gr surface hybrid composites at a rotational speed of 900 rpm due to presence of SiC and Gr acted as load bearing elements and solid lubricant respectively. The observed wear and mechanical properties have been correlated with microstructures and worn morphology.

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Microstructural and mechanical behavior of Al 6061/SiC-Al2O3 composites processed through friction stir processing

Metallurgical and Materials Engineering ◽

10.30544/495 ◽

2020 ◽

Author(s):

Mohana Rao Chanamallu ◽

K. Meera Saheb

Keyword(s):

Tensile Strength ◽

Friction Stir Processing ◽

Base Material ◽

Optical Microscope ◽

Material Surface ◽

Influence Of Process Parameters ◽

Friction Stir ◽

Maximum Tensile Strength ◽

Al 6061 ◽

Favorable Conditions

Metal Matrix Composite (MMC) reinforced in friction stir processing (FSP) has increased insights that can affectively attain the desired mechanical properties for the manufactured samples. The favorable conditions of carbides are considered for reinforcing the SiC particles into the Aluminum 6061. The methodology of fabricating Aluminum 6061 comprises of three materials, Al 6061-SiC-Al2O3. The experimental evaluation of the composite Aluminum 6061-SiC-Al2O3 includes the influence of process parameters on microhardness, tensile strength, and microstructure. As a result of the reinforcement of nanoparticles processed in FSP, the properties of composite material increased satisfactorily. The sample S3 observed to be having a maximum tensile strength of 185 MPa. The larger, the better condition is adopted to analyze the tensile strength of the fabricated samples. The optimum condition for maximum tensile strength was found at 900 RPM, 15 mm/min, and composition 3. The hardness profiles at different zones of friction stir processing (FSP), viz., Heat Affected Zone (HAZ), Thermo Mechanical Affected Zone (TMAZ), Nugget Zone (NZ) were examined. The characterization techniques deployed were optical microscope (OM), and scanning electron microscope (SEM) studies for microstructural behavior. The result shows that the reinforcements were tightly embedded into the base material surface. The spherical grains are formed in the reinforcement region.

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Characterization of Microstructural Refinement and Hardness Profile Resulting from Friction Stir Processing of 6061-T6 Aluminum Alloy Extrusions

Metals ◽

10.3390/met8070552 ◽

2018 ◽

Vol 8 (7) ◽

pp. 552 ◽

Cited By ~ 3

Author(s):

Nelson Netto ◽

Murat Tiryakioğlu ◽

Paul Eason

Keyword(s):

Friction Stir Processing ◽

Base Material ◽

Hardness Profile ◽

Size Distributions ◽

Coarse Particles ◽

Microstructural Refinement ◽

Friction Stir ◽

The Matrix ◽

Single Size

In this study, the change in microstructure and microhardness adjacent to the tool during the friction stir processing (FSP) of 6061-T6 extrusions was investigated. Results showed that the as-received extrusions contained Fe-rich constituent particles with two distinct size distributions: coarse particles in bands and finer particles in the matrix. After FSP, Fe-containing particles exhibited single-size distribution and the coarse particles appeared to be completely eliminated through refinement. Microhardness tests showed the presence of four distinct zones and that hardness increased progressively from the dynamically recrystallized closest to the tool, outward through two distinct zones to the base material. The similarities and differences between the results of this study and others in the literature are discussed in detail.

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Microstructural refinement and property enhancement of cast light alloys via friction stir processing

Scripta Materialia ◽

10.1016/j.scriptamat.2007.09.062 ◽

2008 ◽

Vol 58 (5) ◽

pp. 361-366 ◽

Cited By ~ 179

Author(s):

Z.Y. Ma ◽

A.L. Pilchak ◽

M.C. Juhas ◽

J.C. Williams

Keyword(s):

Friction Stir Processing ◽

Microstructural Refinement ◽

Light Alloys ◽

Friction Stir

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Fabrication of Cu Surface Composite Reinforced by Ni Particles Via Friction Stir Processing: Microstructure and Tribology Behaviors

Journal of Tribology ◽

10.1115/1.4037069 ◽

2017 ◽

Vol 140 (1) ◽

Cited By ~ 5

Author(s):

Mohsen Pezeshkian ◽

Iman Ebrahimzadeh ◽

Farhad Gharavi

Keyword(s):

Friction Stir Processing ◽

Traverse Speed ◽

Optical Microscope ◽

Wear Properties ◽

Friction Stir ◽

Surface Composite ◽

Hardness Tester ◽

Different Dimensions ◽

Pin On Disk ◽

Tool Rotation

In the present investigation, friction stir processing (FSP) was used to integrate Ni particles into the surface of copper in order to fabricate a surface composite. Determining an optimized percentage of Ni particles, different dimensions of grooves were machined into the Cu plates. Then, the specimens' grooves were filled by nickel reinforcement particles, and friction stir process was performed on the specimens with tool rotation speed of 800 rpm and traverse speed of 50 mm/min. Optical microscope (OM) and scanning electron microscope (SEM) were used to evaluate the microstructure. Pin-on-disk test was performed to evaluate wear properties using pins manufactured from the FSPed zone. Also, Micromet-Buehler Vickers hardness tester was used to test the FSPed surfaces' microhardness. The results show that the best properties are obtained when using 2 × 2 mm groove. In this situation, microhardness and wear properties were improved as 40% and 60% compared to the substrate, respectively.

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