SAAco which are knowledge-based companies, in addition to significant industrial experience, have also had valuable activities in the field of research; Therefore, SAAco with all its personnel is ready to carry out any research activity and project that is in its field of activity.
Scientific and research abilities
- Metals forming, analysis and optimization of manufacturing processes
- Finite element analysis of forming processes
- Investigation of residual stresses
- Investigation of fatigue behavior and other mechanical tests of materials
- Investigation of corrosion behavior, microstructural study
- Friction welding (dotted and linear
Part of the projects done
- Compressor motor blade rolling and their process simulation (Industrial production of Inconel 718 compressor blades)
- Mold design and design and construction of compressor blade preform to produce cold rolled parts (For two straight and twisted blades)
- Design and manufacture of combustion chamber assembly fixtures in the aviation industry
- Spark and Combustion Casing assembly with brazing in air motors
- Making telecommunication filters
- Design, analysis and manufacture of earthquake test device fixtures
- Residual stresses on sheets and metal strips resulting from ECAR process for the production of fine-grained materials (micro and nano) and microstructure inspection
- Design and manufacture of friction-stir extrusion device and production of wire sample
- Investigation of samples produced by step formation method
Articles
Description
The layer removal technique and the X-ray diffraction method have been employed to evaluate the residual stresses through the thickness of aluminum alloy 5083 processed by equal channel angular rolling (ECAR). ECAR is a severe plastic deformation process that introduces shear deformation to sheet metals. The process has been completed on 2 mm thick strips passed three times through die channels in a continuous manner. In this work, the profile of residual stresses was quantitatively determined. It was observed that after the ECAR process, the residual stress magnitudes were changed from approximately zero in annealed condition up to half of the yield strength value of ECARed samples. The distribution of the residual stresses was found to be non-uniform through the thickness and the ECARed sample was compressive at the top surface while it was tensile at the bottom surface.
Description
Purpose
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Studying manufacturing process of compressor blade can reduce the production cost and time in aircraft turbo‐engine industries. In the cold roll‐forging of thin compressor blades, the elastic behavior of machine structure and rolls is considerable due to the higher volume of roll separating force. Owing to this kind of elastic deformation during rolling, the adjusted gap between the rolling dies is increased and this causes unexpected flow of material, shape and thickness. The purpose of this paper is to present a new approach for simulation of cold rolling of thin blades and studying the effect of elastic behavior of the machine structure as well as rolls deflection on the material flow and roll separating force.
Design/methodology/approach
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In this paper, the process has been investigated using experimental test and simulation by introducing a new approach in a decision‐making flowchart. Instead of …
Description
Equal channel angular rolling (ECAR) method is one of the severe plastic deformation (SPD) processes which can develop a shear deformation causing considerable residual stress into a sheet metal. In this work, the incremental hole-drilling (IHD) method was applied to determine the through-thickness residual stress distribution. The ECAR was first carried out on a 2 mm Al 5083 sheet for three passes through the channels. The residual stress field was then evaluated using the IHD method. The calibration coefficients A n and B n were obtained by finite element method. It was observed that the residual stress profile through the material thickness was non-uniform and it changed from compressive at the top surface to tensile at the bottom surface in rolling direction. Also, the integral method as an alternative method of calculation was used to determine the residual stresses. There was a good agreement between …
Description
The residual stress within a surface layer of aluminium alloy sheets introduced through equal channel angular rolling as a severe plastic deformation process is studied in this article. The channel oblique angle, the route of feeding and the number of passes are the main equal channel angular rolling parameters that are found to influence the residual stress magnitude and distribution. Two aluminium alloys (Al5083 and Al6061) are analysed with the residual stress magnitudes determined using the X-ray diffraction method. When a sheet metal is processed using the equal channel angular rolling method, the surface residual stress in the rolling direction becomes compressive at the top surface and tensile at the bottom surface. Therefore, a nonuniform stress distribution is introduced into the specimen. By reducing the channel oblique angle of the die set from 130° to 110°, the surface residual stress of Al5083 …
Description
In the rolling process, the material undergoes plastic deformation due to flow stresses caused by the roller pressure. In this article, first, the process of cold rolling of compressor blades was studied by means of experimental testing and simulation utilizing deformable rollers. Then, the pressure distribution on the blade’s surface was investigated during the rolling process. The results show that the pressure distribution is not assumed as a known common hill shape, but depends totally on the caliber section. The highest values of pressure are associated with areas close to the edges of the section which are affected by more reduction and stress, and thus, the surface pressure diagram changes to a saddle shape distribution. The simulation and experimental results are calculated and compared showing a good agreement.
Description
Friction stir extrusion (FSE) is a process in which a sample is produced through the heat generated by the friction between die and materials, and the extrusion pressure. The extruded sample could be wire, tube, rod or another form. The wired samples were produced of aluminum alloy AA7022 at different rotational speeds and extrusion forces, and impacts of these two parameters were studied. The samples produced at higher rotational speeds and lower forces had a far better surface quality and less surface cracks were seen on them. The optical microscopy and scanning electron microscopy (SEM) were used to examine the microstructural properties of samples and the mechanical properties of specimens were studied by micro hardness and compression tests. Using X-ray diffraction technique and Rietveld method, the average crystallite size and micro-strain and dislocation density of samples were calculated …
Description
Equal channel angular rolling (ECAR) is a severe plastic deformation (SPD) process in order to achieve ultrafine-grained (UFG) structure. In this paper, the mechanical properties of ECAR process using artificial neural network (ANN) and nonlinear regression have been illustrated. For this purpose, a multilayer perceptron (MLP) based feed-forward ANN has been used to predict the mechanical properties of ECARed Al5083 sheets. Channel oblique angle, number of passes and the route of feeding are considered as ANN inputs and tensile strength, elongation and hardness are considered as the outputs of ANN. In addition, the relationship between input parameters and mechanical properties were extracted separately using nonlinear regression method. Comparing the outputs of models and experimental results shows that models used in this study can predict and estimate mechanical properties appropriately. Where, the performance of ANN model is better than the correlations to predict mechanical properties. Finally, the developed outputs of neural network model are used to analyze the effects of input parameters on tensile strength, elongation and hardness of ECARed Al5083 sheets.
Description
Friction stir extrusion (FSE) is a process based on the heat generated by friction between die and materials in which a sample is produced through consolidation and extrusion of precursor materials such as metal chips. In this paper, the wire samples produced by friction extrusion of aluminum alloy AA7022 chips are investigated. The samples were extruded at different rotational speeds and extrusion forces, and impacts of these two parameters were studied. At first, structural properties of samples were studied using optical microscopy and scanning electron microscopy (SEM). The result showed that the samples produced at higher rotational speeds and lower forces had a far better surface quality and lower surface crack were seen on them. On the other hand, the temperature of process and grain size were increased with rise of rotational speed. The SEM micrographs showed that by changing rotational speed …
Description
In the paper, structural parameters and mechanical properties of Al5083 alloy sheet during equal channel angular rolling (ECAR) process and their relationship are studied. In order to evaluate the effect of ECAR process, Al5083 strips were subjected to the ECAR process for 1, 2, and 3 passes through the die channel angles 110°, 120°, and 130° at two routes. The effect of the process on the microstructural evolution of samples was investigated by means of x-ray diffraction and EBSD techniques. X-ray pattern has been analyzed using Rietveld method to compute structural parameters, including microstrain, average crystallite size, and dislocation density. The results showed that the dislocation density and microstrain were increased, and crystallite size was decreased during ECAR process. It was found that the behavior of variations in mechanical properties was in accordance with the dislocation density …
Description
Equal channel angular rolling is a severe plastic deformation process which produces an ultrafine-grained structure and improves the mechanical properties of the samples. In this article, using the slitting method experimentally and finite element simulation, the residual stress distribution in an equal channel angular rolled Al alloy 5083 specimen was investigated. First, by applying the slitting technique on the considered specimen, the produced strains were measured and recorded. Then by employing the series expansion method, the through-thickness residual stresses were calculated. The compliance matrix was obtained by means of finite element analysis and 16 terms of the Legendre polynomial (L2 through L17) were used to get the compliance coefficients. According to the finite element results, the residual stresses were created in the sample because of different plastic strain deformation at the same times …
Description
The equal channel angular rolling (ECAR) is one of the severe plastic deformation processes, which can develop a shear deformation into a sheet metal. In this process, internal stresses are created due to the different strain levels experienced in different locations at the same time. The incremental hole drilling method is an effective technique for the evaluation of the through-thickness residual stress distribution in the metal sheets processed by the ECAR. In this work, the residual stresses as the macro stresses have been considered by the help of the incremental method and FEM for numerical calculation of the calibration coefficients. In addition, the FE simulation has been used to investigate the residual stress profile through the thickness. It was observed that the ECARed sample was compressive at the top surface while it was in tension at the bottom surface and the stress profile was not uniform through the material thickness. A comparison between the hole drilling measurements and the FE simulation results showed a good agreement.
Description
The cold roll bonding (CRB) is a type of bonding process between similar and/or dissimilar metals that is bonded through plastic deformation via rolling process at room temperature. In addition, the accumulative roll bonding (ARB) process is considered as one of the methods for applying severe plastic deformation (SPD) with the ability to achieve ultra-fine grains (UFG) structure and improved mechanical properties. In this research, a combined method was suggested consisting of ARB and CRB processes in order to fabricate UFG copper strip with simultaneous increase of strength and electrical conductivity. Microstructure, mechanical properties, and electrical conductivity of copper specimen fabricated via combined method and ARB processes were investigated. Field emission scanning electron microscope (FESEM) micrographs showed in the crystalline structure of the specimen fabricated via combined method …
Description
Friction stir extrusion (FSE) is known as an innovative manufacturing technology that makes it possible to directly produce wire via consolidation and extrusion of metal chips or solid billets. In this study, wire samples were produced using aluminum alloy AA7022 machining chips by the use of the FSE. To this end, the microstructures and mechanical properties of the base material (BM) and the extruded samples were investigated. The corrosion resistance of the given samples was also determined using potentiodynamic polarization technique. The results showed that the samples manufactured at higher rotational speeds possessed good surface quality, the process temperature and the grain size similarly increased following the rise in rotational speed, and the mechanical properties consequently decreased. Using the FSE led to crystallite refinement, increase in volume fraction of grain boundaries, as well as re …
Description
This paper studies the shear and peel strength of composite AA1050 aluminum and SS 316 steel manufactured by accumulative roll bonding (ARB) process. The ARB samples were tested for shear and peel strength under a single axial tensile test. The layer strength was measured in each sample and the results of the experiments were compared. The results showed that the shear strength of layers was higher than the peel strength; also the microstructure of the sheet after performing 5 cycles of the ARB process was observed. To test the strength of the samples during different passes of the process, tensile tests were carried out; the results indicated a general increase in strength. Further studies on the scanning electron microscope (SEM) images of the fracture sections of the samples showed that by increasing the number of passes, the thickness of the steel layers was less than that in the pass 3 of these layers to tear. In the following, hardness changes along the sheet thickness were studied in successive passes. The results indicated that the pass 2 had an impressive increase in hardness.
چکیده
یکی از روشهاي نـوین اتصـال انـواع آلیاژهـاي آلومینیـوم عملیـات حرارتی پذیر، روش جوشکاري اصـطکاکی اغتشاشـی اسـت. امـروزه شکل دهی ورق هاي حاصل از این روش مورد توجه قرار گرفته اسـت. به منظور ایجاد شکل هاي پیچیده با عمق زیاد و دستیابی به استحکام بالا که با روش سنّتی امکان پذیر نیست، از روش نـوین شـکل دهـی تدریجی استفاده می شود. روش شکل دهـی تـدریجی تـک نقطـه اي روشی نوظهور و انعطاف پذیر براي تولید کـم و سـاخت مـدل اولیـه می باشد. در این مقاله به مطالعه تجربی فرآیند شکل دهی تدریجی بر روي ورق آلومینیــوم 6061 حاصــل از روش جوشــکاري اصــطکاکی اغتشاشی پرداخته شده است. در گام اول، اثر سرعت دورانی و سرعت پیشروي ابزار بر خواص مکانیکی ناحیـه جـوش در آلیـاژ آلومینیـوم 6061 بررسی و پارامترهاي مطلوب استخراج شد. در گام بعدي، اثـر روانکار، سرعت دورانی، سرعت پیشروي و مسیر ابزار بر میزان کاهش ضخامت (نازك شدگی) و عمق شکست درفرآیند شکل دهی تدریجی مورد بررسی قرار گرفـت. نتـایج حاصـل نشـان داد روانکـار و مسـیر ابزار،باعث بهبود نازك شدگی و افزایش شکل پذیري می شوند.
واژه هاي کلیدي
فرآیند شکل دهـی تـدریجی تـک نقطـه اي، جوشـکاري اصـطکاکی- اغتشاشی، نازك شدگی، شکل پذیري، ورق آلومینیوم 6061
چکیده
یکی از روشهاي نوین اتصال انواع آلیاژهاي آلومینیوم عملیات حرارتی پذیر، روش جوشکاري اصطکاکی اغتشاشی
(Friction stir welding) است. امروزه شکل دهی ورق هاي حاصل از این روش مورد توجه قرار گرفته است. به منظور ایجاد شکل هاي پیچیده با عمق زیاد و دستیابی به استحکام بالا که با روش سنتی امکان پذیر نیست، از روش نوینشکل دهی تدریجی (Incremental sheet forming) استفاده می شود. روش شکل دهی تدریجی تک نقطه اي روشی نوظهور و انعطاف پذیر براي تولید کم و ساخت مدل اولیه می باشد. در این مقاله به مطالعه تجربی فرآیند شکل دهی تدریجی بر روي ورق آلومینیوم 6061 حاصل از روش جوشکاري اصطکاکی اغتشاشی پرداخته شده است. در گام اول، اثر سرعت دورانی و سرعت پیشروي ابزار بر کیفیت ظاهري و خواص مکانیکی ناحیه جوش در آلیاژ آلومینیوم 6061 بررسی و پارامترهاي مطلوب سرعت دورانی و پیشروي ابزار استخراج شد. در گام بعدي، اثر روانکار، سرعت دورانی، سرعت پیشروي و مسیر ابزار بر کیفیت سطح و عمق شکست پس از شکل دهی تدریجی مورد بررسی قرار گرفت. نتایج حاصل نشان داد روانکار و مسیر ابزار، باعث بهبود کیفیت سطح و افزایش شکل پذیري می شوند.
کلمات کلیدي
جوشکاري اصطکاکی اغتشاشی، شکل دهی تدریجی، ورق آلومینیوم 6061، کیفیت سطح
