Migration to Third Generation : Markets Cenario

Alex Nourouzi 대한전자공학회 1998 CDMA International Conference and Exhibition Vol.- No.-

Optimization of semi-solid metal processing of A356 aluminum alloy

S. Nourouzi,H. Baseri,A. Kolahdooz,S. M. Ghavamodini 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.12

Semi-solid metal (SSM) processing has been recognized as an advanced process to produce high-quality and low-cost engineering components. The cooling slope method is a simple route that can develop non-dendritic slurry for various purposes with reduced equipment and processing costs. In this study, the cooling slope method was employed to produce the A356 feedstock in SSM processing. The dendritic primary phase in the conventionally cast A356 alloy has transformed into a non-dendritic one through the use of ingots cast over a cooling plate with a different pouring temperature. After pouring, the melt that becomes semi-solid at the end of the plate is consequently poured into cylindrical steel molds with different mold temperatures. Also, the process has been conducted in different cooling slopes and different cooling lengths. Then, a back-propagation neural network has been designed to correlate the process parameters to grain size. Finally, genetic algorithm (GA) has been used to optimize the process parameters. Results indicate that the pouring temperature, mold temperature, cooling slope, and cooling length have significant effects on size and morphology of α-Al phase. The GA can optimize the process as well.

Investigation of the controlled atmosphere of semisolid metal processing of A356 aluminium alloy

A. Kolahdooz,S. Nourouzi,M. Bakhshi Jooybari,S. J. Hosseinipour 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.10

The cooling slope (CS) method is one of the semi-solid methods in which the molten alloy with a suitable amount of superheat ispoured on a cooling slope to achieve a fine and non-dendritic structure. After pouring, the melt, which becomes semisolid at the end ofthe plate, is subsequently poured into a cylindrical steel mold with different mold temperatures. Also, the process has been done in differentcooling slopes and different cooling lengths. This work, at first discusses the effect of these parameters on the final microstructure ofA356 aluminum alloy and then the effect of the controlled atmosphere is discussed. Also, in this research, the advantages of using thecontrolled atmosphere system are discussed by tests such as XRD, SEM and ultrasonic test. Results indicate that the pouring temperature,mold temperature, cooling slope and cooling length have significant effects on the size and morphology of α-Al phase. Also, the controlledatmosphere could optimize the process as well and increase the mechanical properties of alloy.

Experimental investigation of thixoforging parameters effects on the microstructure and mechanical properties of the helical gearbox cap

A. Kolahdooz,S. Nourouzi,M. Bakhshi Jooybari,S. J. Hosseinipour 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.10

The purpose of this work is to discuss the microstructures and mechanical properties of thixoforged helical gearbox caps. The mechanicalproperties of semi-solid components can be improved by controlling the process parameters such as solid fraction of alloy, dietemperature, applied pressure, punch velocity, and heat treatment conditions. In this paper, the effects of forming parameters on the microstructuresand mechanical properties of thixoforged A356 helical gearbox caps with an arbitrary shape are studied. The mechanicalcharacteristics were investigated by changing the applied pressure, die temperature, specimen temperature and holding time. The resultsshowed that by increasing the applied pressure from 100 MPa to 150 MPa, the average grain diameter was decreased about 7% and theshape factor was increased about 11%. Also, by increasing the die temperature, the hardness and forming load were decreased about 13%and 21%, respectively. The results illustrated that by increasing the specimen temperature and holding time, there would be an increase inthe grain size of primary α-Al phase, so the hardness of the specimens is decreased.

Textural Evaluation of Al–Si–Cu Alloy Processed by Route BC-ECAP

Esmaeil Damavandi,Salman Nourouzi,Sayed Mahmood Rabiee,Roohollah Jamaati,Jerzy A. Szpunar 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.8

In this study, route Bc of the equal channel angular pressing (ECAP) method has been successfully applied to the Al–Si–Cualloy at 400 °C. Scanning electron microscopy (SEM) and electron backscatter difraction (EBSD) were used to analyze themicrostructure. Texture evolution was studied by the X-ray difraction (XRD) technique. The microstructural results showedthat at least four passes of route BC need to access uniform distribution of fne intermetallic compounds (IMCs) and eutecticsilicon particles (ESPs). The particle stimulated nucleation (PSN) and continuous dynamic recrystallization (CDRX) aretwo important mechanisms to refne the aluminum matrix in Al–Si–Cu alloy. The texture results revealed that owing to achange in the rotation direction of route BC in consecutive passes, this process led to creating diferent types of textures, inboth qualitative and quantitative senses. The A*1Ѳ and A*2Ѳ were the strongest texture components after the fourth pass ofroute BC. Regardless of route A, the route BC-ECAP process led to strengthen the {100}⟨001⟩ and {011}⟨100⟩ componentsand weaken the {001}⟨310⟩ component. Three components, {100}⟨110⟩, {021}⟨501⟩, and {013}⟨313⟩ were developed byroute BC. The efects of route BC on texture homogeneity were also studied.

Experimental investigation of thixoforging process on microstructure and mechanical properties of the centrifugal pump flange

A. Kazemi,S. Nourouzi,A. Kolahdooz,A. Gorji 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.7

In this paper, a thixoforging method is studied as one of the semi-solid forming processes. At the first step, the influence of semi-solidtemperature, holding time, and ram speed of the hydraulic press are investigated on microstructure and mechanical properties of thixoforgedA356 aluminum alloy parts. For this purpose, the slope plate casted billets are heated up to semi-solid temperature of 580, 590,and 600˚C and holding time of 5, 10, and 15 minutes and then are deformed using the press with ram speeds of 1, 3 and 5 mm/s. Resultsshow that the best mechanical properties are related to the thixoforged specimen with the finest microstructure which is thixoforged atsemi-solid temperature of 600°C, holding time of 5 minutes and ram speed of 5 mm/s. Afterwards, the T6 heat treatment is performed toimprove mechanical properties of parts produced by thixoforging process. At the final step of experiments in order to investigate theeffect of using slope plate prior to reheating on microstructure and mechanical properties, semi-solid forging is done by using the gravitycasted billet.

Evaluation of surface residual stresses in HVOF sprayed WC-12Co coatings by XRD and ED-hole drilling

M. Jalali Azizpour,S. Nourouzi 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.9

Thermally sprayed coatings are inherently associated with residual stresses in the coatings. These stresses have a noticeable effect on the physical and mechanical properties of coatings. The high speed hole drilling method is widely used to measure the residual stress. Due to the nature of the thermally sprayed coatings, the application of this method for WC/Co coatings has some limitations. In the current study, WC-12Co coatings were deposited using HVOF thermal spraying. The electro discharge hole drilling method was developed to measure the through thickness residual stress in WC-Co thermally sprayed coatings. Morphological studies were conducted using optical microscopy and scanning electron microscopy (SEM) to evaluate the powder and coating characteristics. The sin2ψ method was used to evaluate the surface residual stress by means of XRD. The residual stress at the surface using EDM and XRD was approximately -32.54 MPa and -40.6 MPa respectively. The experimental results reveal that the stress curves are not uniform through the coating thickness. It has been found that the mean residual stress is of approximately -126 MPa. Obtained results are in good agreement with the reported values from literatures. The developed method confirms the feasibility of residual stresses measurement for HVOF thermally sprayed WC-Co coatings.

Analysis of welding parameters effects on microstructural and mechanical properties of Ti6Al4V and AA5052 dissimilar joint

Hossein Rostami,Salman Nourouzi,Hamed Jamshidi Aval 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.7

The aim of this investigation was to explore the effect of geometric tool parameters and tool probe offset on the properties of friction stir welded of 2 mm thick plates of Ti6Al4V to AA5052-H32 joints. In a probe offset distance of 0.5 mm, sound dissimilar joint with tensile strength higher than 94 % of the parent AA5052 alloy strength is produced. Increasing the probe offset distance result in more homogenous and higher quantity of titanium alloy particles in the weld nugget. Increasing welding heat input results in change of fracture zone from TMAZ of AA5052 side to weld interface. It was found that the tool with square frustum pin produces joints without defect and high strength compared to the cylindrical pin.

Investigation of Simultaneous Effects of Cooling Slope Casting and Mold Vibration on Mechanical and Microstructural Properties of A356 Aluminum Alloy

Mahdieh Jahanbakhshi,Salman Nourouzi,Reza Naseri,Kourosh Esfandiari 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.6

Aluminum alloys are used in numerous industrial fields due to low weight and high strength to weight ratio. Among differentforming processes, semi-solid casting is one of the most attractive methods for obtaining improved structures as well asminimizing the porosity and segregation problems of conventional casting. In this study, simultaneous employment of coolingslope and introducing mechanical vibration into the melt during solidification is investigated from viewpoint of microstructureof as-cast A356 aluminum alloy. Obtained results demonstrate that by simultaneous employment of cooling slope andmechanical vibration, more refinement can be occurred in comparison to distinct employment of these two procedures. Asa result of this research, in this experimental condition with vibration frequency of 20 Hz and time equal to 3 min, the finalaverage grain size of 50 μm and shape factor of 0.66 can be achieved. Furthermore, mechanical properties of as-cast alloyare also enhanced so that Brinell hardness number and compression strength of the optimum sample are determined equalto 74 Brinell and 486 MPa, respectively.

Numerical Investigation into the Effect of Uniaxial and Biaxial Pre-Strain on Forming Limit Diagram of 5083 Aluminum Alloy

F. Zhalehfar,S.J. Hosseinipour,S. Nourouzi,A.H. Gorji 한국소성가공학회 2011 기타자료 Vol.2011 No.8

In this paper, numerical simulations are carried out to determine the forming limit diagram (FLD) of 5083 aluminum alloy. The aim is to predict the effect of strain path change on the forming limit curve (FLC) of this alloy. For this purpose, out-of-plane formability test method with hemispherical punch was simulated by using commercial finite element software, ABAQUSE 6.9. In the first stage, square blanks were modeled and then some of them were pre-strained uniaxially by tension test and some others were pre-strained biaxially by stretching over the hemispherical punch. In the second stage, the formability test specimens’ models were prepared by trimming the pre-strained blanks with the longitudinal axis parallel and perpendicular to the rolling direction. For trimming, a program was written in MATLAB 7.6 which could determine the new elements and introduce their properties to the FEM model. Ductile fracture criteria were used to predict failure. Furthermore, forming limit stress diagram (FLSD) was determined. The numerical results were compared with the experimental findings. Uniaxial pre-straining increased and shifted the FLC to the left hand side of the diagram for both parallel and perpendicular to the rolling direction. Biaxial pre-straining shifted the FLC to the right hand side of the diagram for both directions, and also decreased the FLC for the specimens parallel to the rolling direction.