جستجوی مقالات مرتبط با کلیدواژه « فرآیند اصطکاکی اغتشاشی » در نشریات گروه « فنی و مهندسی »

The friction stirring process is one of the new processes in the production of metal matrix composites. Choosing the right parameters for the uniform distribution of particles in this process is vital. One of the important parameters in this process is the number of processes passes and the change in the direction of the tool rotation between the process passes. In this study, the effect of the number of passes and the change in the tool rotation direction on the distribution of SIC particles in aluminum 6061 has been investigated. Aluminum 6061 is one of the hard deposit able aluminum alloys, in which magnesium and silicon are the main elements. First, samples are produced using one, two, and four process passes, with and without changing the tool rotation direction between the process passes. Then, the distribution of particles in the base metal is studied using macro- and microscopic photographs. The results showed that the number of processes passes and the change in the tool rotation direction have a significant effect on the uniform distribution of particles.

In the present study, friction stir process (FSP) was used to produce AL/ZrO2/ZrSiO4 surface hybrid composite at a fixed rotation speed of 1400 rpm and traverse speeds of 20, 25, 31.5 and 40 mm/min. Therefore, the purpose of the mentioned study is to investigate the effect of tool traverse speed on the microstructure, hardness and wear behavior of the above-mentioned surface hybrid composite and compare it with base material aluminum 5052. Investigations showed that as a result of FSP operation, a fine-grained structure is created, which improves the hardness and wear resistance of the samples compared to the base sample with the presence of ZrO2 and ZrSiO4 particles. Also, the results showed that among the FSP samples, the sample with a speed of 20 mm/min has the highest hardness and wear resistance. The reason for this is that in this sample, due to the lower traverse speed compared to other samples, more heat has been generated, which has led to more suitable particle distribution and more fine particles. Therefore, in the sample with the traverse speed of 20 mm/min, the hardness and wear resistance increases by 27.3% and 68.9% respectively compared to the base material sample. Also, the examination of the wear surfaces of the samples showed that the wear mechanism in the base sample is strong adhesive wear, and as a result of the FSP operation and surface compositing due to the fineness of the grains and the increase in hardness, the wear mechanism has become weak adhesive, so the wear resistance of the sample is FSPs have been improved.

According to friction stir processing For production of surface composites with constant progress and rotational speed, samples are made in different number of passes (1,3.5) and to obtain the stress range and adjust the device and apply the fatigue and tensile test is performed. Results of micro-structure study showed that with increasing number of passes, the distribution of underlying particles is improved, and maximum yield strength is for one sample and three samples have the longest Hight cycle life fatigue. The goal is improve the metal micro-structure with the new friction stirring technique, result shown the strength of the metal is improved, and resistance to wear, fatigue and corrosion is increased, it causes improvement of form-ability, which results increase in the number of The pass has led to a homogeneous and uniform distribution of reinforcing particles, in fact, increasing the number of passes in the process has led to a better distribution and separation of silicon-carbide particles in ground phase.

Friction stir process (FSP) was used to improve hardness and tribological properties of Al-5083 aluminum alloy through formation of metal matrix composite (MMC) material. The process involved the use of titanium diboride powder (TiB2) and carbon nanotubes reinforcing materials. The number of passes during the process was varied. Observations of the microstructure of the composite materials were made using scanning electron microscopy (SEM), while the composited surface layers were examined using microhardness testing. After conducting four passes using FSP, the surface nanocomposite obtained from carbon nanotubes and TiB2 yielded a maximum increase in hardness of 32.3%, and 21.6% compared to the base alloy respectively. Moreover, the samples produced with four passes, containing carbon nanotubes, showed a hardness 8% greater than the samples produced with the same number of passes, but with TiB2. Additionally, the highest wear resistance was also obtained using four passes. The wear resistance exhibited by the carbon nanotube-reinforced composite was approximately 45% greater than the TiB2 powder-reinforced composite. Hence, the use of FSP can potentially increase the working life of the part in wear conditions by up to 3.5 times.

Crack nucleation mechanisms, its growth, and the determination of critical failure parameters are of industrial importance. Therefore, it is inevitable to study the mechanical behavior of cracked materials under applied load during severe plastic deformation. The present study studied the mode I fracture behavior, mechanical properties, and microstructure characterization of the 6061 aluminum alloy fabricated by friction stir processing (FSP). For this purpose, a milling machine made a perfect stirring zone to perform the FSP method with the specific non-consumable tool. According to the tensile test results, the yield and ultimate tensile strength of the FSP-processed sample have increased by 39% and 37%, respectively. Based on the three-point bending test, the fracture toughness of the processed aluminum was calculated as 10.86 MPa√m, which shows a 14.3% improvement compared to the as-received annealed state. Eventually, the average grain size of the annealed and processed samples was measured as 35 and 15, respectively, which indicated a 57% reduction in the aluminum grain size after FSP. Note that this grain refinement is associated with improved strength and toughness.

This paper presents an investigation into the process parameters and conditions of friction stir processing for aluminum alloy 6061. The effect of process parameters including speed, feed, tool penetration depth, and reinforcement particles on the strength, hardness, and corrosion behavior of the samples are investigated. Tensile test, fracture mapping, and surface hardness measurement, as important mechanical properties, are performed using broken samples. The obtained results show that adding alumina particles in micrometer size with friction stir processing improves the final tensile strength, hardness, and corrosion resistance. The results show that the corrosion behavior of the processed samples is improved by reducing the corrosion rate, corrosion current, and corrosion potential compared to the base metal. The microstructure of the processed samples after the corrosion test shows that samples with micrometer-sized alumina reinforcement particles have fewer holes than others and lead to a more polished and smoother surface.

According to friction stir processing For production of surface composites with constant progress and rotational speed, samples are made in different number of passes (1,3.5) and to obtain the stress range and adjust the device and apply the fatigue and tensile test is performed. Results of micro-structure study showed that with increasing number of passes, the distribution of underlying particles is improved, and maximum yield strength is for one sample and five samples have the longest low cycle life fatigue. The goal is improve the metal micro-structure with the new friction stirring technique, result shown the strength of the metal is improved, and resistance to wear, fatigue and corrosion is increased, it causes improvement of form-ability, which results increase in the number of The pass has led to a homogeneous and uniform distribution of reinforcing particles, in fact, increasing the number of passes in the process has led to a better distribution and separation of silicon-carbide particles in ground phase.

In the present study, friction stir processing (FSP) technique was carried out on the AA2024 sheet at different traverse speed (63 to 250 mm/min) and rotation speed (315 to 800 rpm). The temperature and grain size of stirred zone (SZ) were measured and their relationship was analyzed and effect of FSP parameters on the grain size of SZ was determined. Experiment and analytical investigations revealed that SZ grain size complies the exponential temperature-dependent relationship and can be defined the mathematical equation. Calculations indicate that a change in operational variables (rotation and traverse speeds) makes no variation in strain rate, and it is constant.

The FSP is a method for solid state processing of metal alloys. FP4M milling machine and non-consumable rotary-tools were used to create the necessary heat and further mix copper with titanium-dioxide powder. The base plate is made of copper with a purity of 99.9%. The heat created during the process on the copper piece and the titanium-dioxide nanoparticles in the groove leads to metallurgical changes in the microstructure of the base metal and leads to changes in the size and shape of the grains. The samples were subjected to metallography and microstructure investigations by OP, XRD, corrosion and wear tests. The results show that in the HAZ area, the grains were in the form of a fine grain structure of copper solid solution, containing twin regions with an average grain size of 14, but in the process area, the grains were formed as a distorted and disturbed structure of copper solid solution. The average friction coefficient in the base copper wear diagram is less than one. By matching with the corrosion graph, the base copper sample has better corrosion resistance.

In this article, the friction stir process (FSP) was used to add various weight percentages of silicon carbide (SiC) nanoparticles to the base phase of PA6/NBR. Also, the effect of three variables of the rotation speed tool (ω), traverse speed (V) and the weight percentage of silicon carbide nanoparticle (S) on the mechanical properties (young’s modulus and impact strength) were investigated by response surface methodology (RSM) based on the Box-Behnken design. Scanning electron microscope (SEM) was used to determine the dispersion of nanoparticles in the base phase and the effect of their addition on the microstructure of PA6/NBR thermoplastic elastomer. Moreover, the thermal properties of PA6/NBR/SiC samples with different weight percentages of silicon carbide nanoparticles were investigated by differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA). The values obtained from the regression equations showed that, under optimal conditions of the rotational speed of 1200 rpm, traverse speed of 20 mm/min and the weight percentage of nanoparticles of 3.8 wt. %, the maximum young's modulus and impact strength 665.18 MPa and 62.26 J/m, respectively could be obtained. Also the crystallization and melting temperature increased to 198 and 222.8 °C, respectively.

In this research, the structure and mechanical properties of aluminum 6061 composite with graphene reinforcing nanoparticles produced by friction stir method (FSP) were investigated. The rotation speed of the tool was set from 112 to 280 rpm, the speed of the tool movement in the range of 31.5 to 20 mm/min and the slope of the conical tool was set at 2, 2.5 and 3 degrees.

Characterization was done by tensile tests, microhardness, field emission scanning electron microscope (FESEM) along with X-ray energy spectroscopy (EDS) and optical microscope (OM). The results show that in the presence of graphene as a reinforcement, the mechanical properties are improved.

By increasing the ratio of rotation speed to tool movement speed (advance per revolution) from 0.07 to 0.28 and increasing the tool angle from 2 to 3 degrees, tensile strength enhanced from 338 to 396 MPa, yield strength from 319 to 383 MPa and the elongation increase has increased from 10.9 to 12.3 percent. Also, the micro-hardness in the nugget area increased from 273 to 400 Vickers.

Friction stir processing is widely used for improvement of properties and microstructure of Aluminum, Copper and Magnesium alloys but investigation on steels are limited. Due to the fact that steel alloys, in addition to aluminum, copper and magnesium alloys, have good engineering properties and vast applications in the industry, they need to be processed by friction-stirring process. In this regard, the present research examines the effect of frictional stirring process on grain size, hardness and wear resistance of Ck45 steel due to the number of passes and tool design. In this research, it was shown that the friction-stirring method can be an effective method to increase the hardness and wear resistance of this steel in such a way that increasing the number of passes causes more heat generation per unit length and also affects the grain size, hardness and probably atomic penetration. In general, with the increase in the number of passes, the size of the grains in the stirring area becomes larger, while the final hardness and wear resistance are determined under the joint effects of grain size and hardness. The results indicate that the hardness has increased by 42% and the amount of wear has decreased by 85% compared to the original sample by the frictional stirring process.Keywords

One of the main problems in oil and gas pipelines is abrasion corrosion on the edges of the flow channel in the plug and ball valves. Under normal conditions, the gas is moving at a pressure of about 145 bar and an approximate speed of 70 feet per second; The suspended particles in the gas collide with the edges of the flow channel and cause severe erosion on them. Abrasion resistance of steels depends mainly on their surface properties and can be increased by increasing the surface hardness by friction stir processing (FSP). In this study, A216-WCB steel, which is used in the manufacturing of casting parts for valves, flanges and fittings, was processed using a friction stir process for one and three passes. The microstructure, hardness and wear properties of the processed area were investigated. The results showed that two distinct zones, the stir zone (SZ) and the thermo-mechanical affected zone (TMAZ), are formed in the processed zone. Due to the friction stir process, the ferrite grain size in the stirring region decreased from 25 microns to about 3 microns. The hardness of the stir zone increased from 165 Vickers to about 780 HV. Also, the abrasion resistance of the stirring area increased up to 2.5 times.

In this paper, the addition of silicon carbide (SiC) nanoparticles to polyamide 6 (PA6) / acrylonitrile-butadiene rubber (NBR) blends was performed by friction stir process. In order to achieve optimal mechanical responses of tensile strength and elongation at break, response surface methodology (RSM) was used to optimize the process parameters of rotational speed (ω), traverse speed (V) and material parameter as silicon carbide nanoparticles (S) content. The validation of the mechanical results was done with compare the microstructure of nanocomposite samples by scanning electron microscopy (SEM). Using mathematical models, the results showed that tensile strength and elongation at break are increased by increasing the rotational speed from 800 rpm to 1200 rpm when the values of silicon carbide content and traverse speed are constant. By selecting the rotational speed of 1200 rpm, traversed speed of 20 mm/min, and 2.784 wt.% of SiC process and material parameters, the maximum tensile strength, and elongation at break can be achieved. Observation of scanning electron microscopy images confirmed that the changes in mechanical properties are related to the changes in the elastomeric phase of NBR.

Al-Si alloys are commonly used in the manufacture of auto parts, including pistons. Although this alloy offers desirable properties for use in pistons, several microstructural properties, such as the presence of needle-like silicones or dendrites, interfere with the performance of the components produced. In this study, ZrO2 reinforcing particles were used to produce metal-based composites by friction stir process. First, the microstructural characteristics of the stir zone (SZ) of the samples produced were studied using a optical microscope. The results showed that the friction stir process improves the microstructural properties of the base metal, including the size of the silicon particles, and the distribution of these particles in the base metal. Then the particle distribution and bond quality between ZrO2 and aluminum reinforcing particles were investigated using SEM. Then, hardness and wear tests were performed to determine the wear and hardness of the composites. Pin-on-disk wear tests were performed at speeds of 1 m / s and 2 m / s and normal applied loads of 5 N, 10 N and 20 N. The wear test results showed that the wear resistance of the produced composite was improved by about 172% compared to the base alloy.

The perturbation friction process is a solid state method used to modify the surface, improve mechanical properties, and produce composites. In this research, the effect of effective parameters on the surface compositing of AZ31B / CNT alloy with carbon nanotubes has been investigated by the frictional perturbation process method and Sobel sensitivity analysis. Input parameters in this study were advance speed, rotation speed, weight percentage of carbon nanotubes and number of welding passes, as well as considered outputs including hardness and weight loss. In order to analyze the results, Sobel sensitivity analysis has been used to investigate the qualitative and quantitative impact of inputs on outputs. The results of this study showed that the weight percentage of carbon nanotubes, rotation speed, number of welding passes and advancement speed affect hardness, respectively. The weight percentage of carbon nanotubes, the rotation speed, the number of welding passes and the advancing speed also affect the weight loss.

In this study, using finite element simulation, the effect of seawater corrosion on the fatigue life of 5083 aluminum alloy welded by shielding gas method after turbulent friction process has been investigated. Plates with different dimensions of 49.1 to 49.8 cm3 were modeled and then simulated with conical corrosion attacks, having different diameters and heights and random distribution. Afterward, considering experimentally mechanical properties reported by other researchers, fatigue life was analyzed through ABAQUS software solver. The results of corrosion as well as material properties effects on fatigue life and also the effect corrosion of the useful life of the aluminum alloy were investigated. The results showed that by increasing the corrosion rate of aluminum alloy, it had less resistance to fatigue, so that by creating approximately 1.8% corrosion on the sample surface, a 5.6% reduction in cycle was achieved. The validation of the simulation results in corrosion fatigue analysis, obtained in the present study through the stress-life method, with the use of the results published by other researchers, reveals a good agreement.

Friction stir processing (FSP) was performed on a 2024 aluminum alloy sheet with a thickness of 2.5 mm. Determination of the parameters affecting on the microstructure is very important to investigate the grain size changes in Thermo-Mechanically Affected Zone (TMAZ). In this study, were investigated the effect of tool rotation speed on the microstructure and mechanical properties of the areas around the stir zone when keeping the traverse speed constant. The average grain size in advancing side were decreased from 6 μ to 3 μ by increasing rotation speed from 315 to 500 rpm and were increased from 3μ to 7μ by increasing rotation speed from 500 to 800 rpm. The average grain size in retreating side were decreased from 7μ to 4μ by increasing rotation speed from 315 to 500 rpm and were increased from 4μ to 8μ by increasing rotation speed from 500 to 800 rpm. Also the advancing side’s grain size was smaller than that of the retreatin side. The mechanical properties of advancing and retreating sides were semillar.

In the present paper, an attempt has been made to improve the mechanical properties of 5083 aluminum alloy welded by metal inert gas method followed by frictional stir process using an experimental method. For this purpose, the FSP process was performed in three rotation velocities of 500, 750, and 1000 rpm and with a forward velocity of 100 cm/min. In order to achieve the effect of FSP process on the microstructure of the tested alloy, welding samples, as well as frictional stir process samples, were studied. Thus, the microhardness and tensile strength of each sample were investigated. Then, using the genetic algorithm method, the optimal value of the rotation velocity was calculated. The results showed that the FSP process makes the heat affected area finer in terms of granulation and in addition, defects such as porosity and non-wettability due to the molten weld area are reduced or eliminated by the frictional stir process. On the other hand, the results of optimization indicate that the most suitable strength is obtained at a rotational velocity of 820 rpm. At this speed, the grain size is reduced by 96% compared to the heat affected area in the initial base state. Also, the cross-sectional images of the optimal sample fracture, unlike other samples, show that the fracture did not occur in the weld area, which can be attributed to the removal of cavities in the welded area by the frictional stir process.

In this study, in situ Al-Al3Ni-TiC surface composite was successfully fabricated by friction stir processing (FSP) of AA1050 alloy. For this purpose mechanically alloyed Ni-Ti-C powder mixture prepared by high energy milling for a total duration of 20h, was inserted into Al substrate. Microstructure, microhardness and wear behavior of the composites obtained from 2 and 6 FSP passes were evaluated. Microstructural examinations of MAed powder and composite were performed using an optical microscope (OM) and scanning electron microscope (SEM) equipped with microprobe elemental analysis. The results of the experiments showed that in situ reaction occurred between MAed powder and matrix during friction stir processing and resulted in the formation and distribution of Al3Ni and TiC compounds in the matrix. Al3Ni and TiC compounds increased the hardness and improved the wear resistance of in situ composites.The hardness of the composite obtained from 6 FSP passes (70 HV) increased about 280% compared to the base metal (≈25 HV). The composite obtained from 2 FSP passes showed non-uniform hardness due to incomplete reaction and inhomogeneous distribution of powder particles. The dominant wear mechanisms were identified as abrasive wear and adhesive wear for the base metal and composite obtained from 2 FSP passes, and abrasive wear for the composite obtained from 6 FSP passes.