The Experts below are selected from a list of 21672 Experts worldwide ranked by ideXlab platform
Mostafa Ketabchi - One of the best experts on this subject based on the ideXlab platform.
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enhanced properties of nano grained Pure Copper by equal channel angular rolling and post annealing
Materials & Design, 2012Co-Authors: Asiyeh Habibi, Mostafa KetabchiAbstract:Abstract The Pure Copper sample was severely plastically deformed by 8-pass equal channel angular rolling process. The thermal stability of processed Copper was investigated by measuring the development of microhardness at isochronal annealing temperature. According to variation in microhardness, the recrystallization temperature of Pure Copper after 8 pass of equal channel angular rolling process was 230 °C. The influence of post-annealing on microstructure, mechanical and electrical properties of the 8-pass processed Copper was investigated. Scanning electron microscopy micrographs and X-ray diffraction peak broadening analysis have demonstrated that grain size decreased with post-annealing, which is the reason for the increase in strength of the Copper specimen. The electrical conductivity of sample increased after post-annealing because of the rearrangement of dislocations.
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nano grained Pure Copper with high strength and high conductivity produced by equal channel angular rolling process
Journal of Materials Processing Technology, 2011Co-Authors: Asiyeh Habibi, Mostafa Ketabchi, Mohammad EskandarzadehAbstract:Abstract Equal channel angular rolling, based on the equal channel angular pressing, is a severe plastic deformation process which can develop the grains below 1 μm in diameter. Microstructure, mechanical properties and electrical conductivity of commercial Pure Copper strips processed by equal channel angular rolling were investigated. Scanning electron microscopic micrographs of the strips produced by ten passes of equal channel angular rolling process showed nano-grains ∼70–200 nm in size. Also yield and tensile strengths and microhardness of samples increased with increasing the number of passes, whereas their ductility decreased. The electrical conductivity varied slightly. So via equal channel angular rolling process and by producing nano-grained Pure Copper, the strips can be strengthened with a little decrease in electrical conductivity but it has shortcomings of low elongation and strain hardening.
Asiyeh Habibi - One of the best experts on this subject based on the ideXlab platform.
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enhanced properties of nano grained Pure Copper by equal channel angular rolling and post annealing
Materials & Design, 2012Co-Authors: Asiyeh Habibi, Mostafa KetabchiAbstract:Abstract The Pure Copper sample was severely plastically deformed by 8-pass equal channel angular rolling process. The thermal stability of processed Copper was investigated by measuring the development of microhardness at isochronal annealing temperature. According to variation in microhardness, the recrystallization temperature of Pure Copper after 8 pass of equal channel angular rolling process was 230 °C. The influence of post-annealing on microstructure, mechanical and electrical properties of the 8-pass processed Copper was investigated. Scanning electron microscopy micrographs and X-ray diffraction peak broadening analysis have demonstrated that grain size decreased with post-annealing, which is the reason for the increase in strength of the Copper specimen. The electrical conductivity of sample increased after post-annealing because of the rearrangement of dislocations.
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nano grained Pure Copper with high strength and high conductivity produced by equal channel angular rolling process
Journal of Materials Processing Technology, 2011Co-Authors: Asiyeh Habibi, Mostafa Ketabchi, Mohammad EskandarzadehAbstract:Abstract Equal channel angular rolling, based on the equal channel angular pressing, is a severe plastic deformation process which can develop the grains below 1 μm in diameter. Microstructure, mechanical properties and electrical conductivity of commercial Pure Copper strips processed by equal channel angular rolling were investigated. Scanning electron microscopic micrographs of the strips produced by ten passes of equal channel angular rolling process showed nano-grains ∼70–200 nm in size. Also yield and tensile strengths and microhardness of samples increased with increasing the number of passes, whereas their ductility decreased. The electrical conductivity varied slightly. So via equal channel angular rolling process and by producing nano-grained Pure Copper, the strips can be strengthened with a little decrease in electrical conductivity but it has shortcomings of low elongation and strain hardening.
L Geng - One of the best experts on this subject based on the ideXlab platform.
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effect of heat input conditions on microstructure and mechanical properties of friction stir welded Pure Copper
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2010Co-Authors: P Xue, B L Xiao, Z Y, G M Xie, L GengAbstract:Defect-free friction stir welds of 5-mm-thick Pure Copper plates were produced in relatively low heat input conditions. The characteristics of the microstructure and mechanical properties of the welded joints were investigated. The stir zone (SZ) exhibited equiaxed recrystallized grains, whose size decreased as the heat input was decreased. The percentage of high-angle grain boundaries (grain boundary misorientation angle >15 deg) in the SZ was quite high (90.2 to 94.5 pct) and increased as the heat input was increased. When the heat input was decreased, the percentage of the twin boundaries (TBs) dropped, and the number of the twin lamellas was reduced. Under a very low heat input condition, the typical characteristics of thermomechanically affected zone (TMAZ) were discernible; however, the TMAZ was characterized by a recrystallized grain structure at higher heat input conditions. The grains in the heat-affected zone (HAZ) were slightly coarsened compared to those in the parent material (PM), but the grain size varied a little under different parameters. The hardness of the SZ increased as the heat input was increased, and the lowest hardness appeared at the HAZs where the welds failed. The ultimate tensile strength (UTS) was similar to that of the PM under various heat input conditions, but the yield strength (YS) and elongation were lower. The YS increased as the lowest hardness value increased, and the elongation decreased due to the enhanced strain localization.
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development of a fine grained microstructure and the properties of a nugget zone in friction stir welded Pure Copper
Scripta Materialia, 2007Co-Authors: Z Y, G Xie, L GengAbstract:Defect-free Pure Copper welds were achieved under low heat input conditions of 400–800 rpm for a traverse speed of 50 mm min−1. The grain size of the nugget zones decreased from 9 to 3.5 μm with decreasing rotation rate from 800 to 400 rpm. “Onion rings”, consisting of different-sized grain bands, were observed at 400 rpm, but disappeared at 600–800 rpm. Variations of both microhardness and yield strength of the nugget zones with grain size followed the Hall–Petch relationship.
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development of a fine grained microstructure and the properties of a nugget zone in friction stir welded Pure Copper
Scripta Materialia, 2007Co-Authors: Z Y, L GengAbstract:Defect-free Pure Copper welds were achieved under low heat input conditions of 400-800 rpm for a traverse speed of 50 mm min(-1). The grain size of the nugget zones decreased from 9 to 3.5 mu m with decreasing rotation rate from 800 to 400 rpm. "Onion rings", consisting of different-sized grain bands, were observed at 400 rpm, but disappeared at 600-800 rpm. Variations of both microhardness and yield strength of the nugget zones with grain size followed the Hall-Petch relationship. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
T Saeid - One of the best experts on this subject based on the ideXlab platform.
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prediction of mechanical properties in friction stir welds of Pure Copper
Materials & Design, 2013Co-Authors: Akbar Heidarzadeh, T SaeidAbstract:Abstract This research was carried out to predict the mechanical properties of friction stir welded Pure Copper joints. Response surface methodology based on a central composite rotatable design with three parameters, five levels, and 20 runs, was used to conduct the experiments and to develop the mathematical regression model by using of Design-Expert software. The three welding parameters considered were rotational speed, welding speed, and axial force. Analysis of variance was applied to validate the predicted models. Microstructural characterization and fractography of joints were examined using optical and scanning electron microscopes. Also, the effects of the welding parameters on mechanical properties of friction stir welded joints were analyzed in detail. The results showed that the developed models were reasonably accurate. The increase in welding parameters resulted in increasing of tensile strength of the joints up to a maximum value. Elongation percent of the joints increased with increase of rotational speed and axial force, but decreased by increasing of welding speed, continuously. In addition, hardness of the joints decreased with increase of rotational speed and axial force, but increased by increasing of welding speed. The joints welded at higher heat input conditions revealed more ductility fracture mode.
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effect of tool pin profile on microstructure and mechanical properties of friction stir welded Pure Copper joints
Materials & Design, 2013Co-Authors: H Khodaverdizadeh, Akbar Heidarzadeh, T SaeidAbstract:Abstract In the present study, the effect of tool pin profile on microstructure and mechanical properties of friction stir welded Pure Copper joints were investigated. Two different tools with threaded cylindrical and square pin profiles were used to fabricate the joints at constant rotation rate of 600 rpm and traverse speed of 75 mm/min. Four K-type thermocouples were used to record the temperature histories of samples during FSW. Microstructure features of the joints were characterized by optical microscopy and the obtained images were quantified using image analysis technique. Tension test and Vickers hardness measurements were also performed to characterize the mechanical properties of the joints. Obtained results showed that sample welded using square pin profile had finer recrystallized grain structure and higher mechanical properties relative to sample welded by threaded cylindrical one. These results were attributed to higher eccentricity of the square pin profile and its pulsation effect which led to higher degree of plastic deformation and higher heat input into the joints.
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establishing a mathematical model to predict the tensile strength of friction stir welded Pure Copper joints
Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science, 2013Co-Authors: Akbar Heidarzadeh, T Saeid, H Khodaverdizadeh, A Mahmoudi, E NazariAbstract:This investigation was undertaken to predict the tensile strength of friction stir welded Pure Copper. Response surface methodology based on a central composite rotatable design with four welding parameters, five levels, and 31 runs was used to conduct the experiments and to develop the mathematical regression model by means of Design-Expert software. Four welding parameters considered were tool profile design, rotational speed, welding speed, and axial force. Analysis of variance was applied to validate the predicted model. Confirmation experiments including microstructural characterization and conducted tensile tests showed that developed models are reasonably accurate. The results showed that the joints welded using the square and triangular tools had higher tensile strength compared to the joints welded using other tools. The increase in tool rotational speed, welding speed, and axial force resulted in increasing the tensile strength of the joints up to a maximum value. Also, the developed model showed that the optimum parameters to get a maximum of tensile strength were rotational speed, welding speed, and axial force of 942 rpm, 84 mm/min, and 1.62 kN, respectively.
Z Y - One of the best experts on this subject based on the ideXlab platform.
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achieving friction stir welded Pure Copper joints with nearly equal strength to the parent metal via additional rapid cooling
Scripta Materialia, 2011Co-Authors: P Xue, B L Xiao, Qiuyan Zhang, Z YAbstract:Friction stir welded (FSW) Pure Copper joints with nearly equal strength to the parent metal were obtained at 400 rpm/50 mm min(-1) via additional rapid cooling with flowing water. Significantly reduced heat input with a peak temperature of 130 degrees C and duration of 4 s above 100 degrees C in the thermal cycle was achieved in the heat-affected zone, resulting in the retainment of the original high dislocation density of the parent metal. This work provides an effective strategy to enhance the strength of FSW joints. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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effect of heat input conditions on microstructure and mechanical properties of friction stir welded Pure Copper
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2010Co-Authors: P Xue, B L Xiao, Z Y, G M Xie, L GengAbstract:Defect-free friction stir welds of 5-mm-thick Pure Copper plates were produced in relatively low heat input conditions. The characteristics of the microstructure and mechanical properties of the welded joints were investigated. The stir zone (SZ) exhibited equiaxed recrystallized grains, whose size decreased as the heat input was decreased. The percentage of high-angle grain boundaries (grain boundary misorientation angle >15 deg) in the SZ was quite high (90.2 to 94.5 pct) and increased as the heat input was increased. When the heat input was decreased, the percentage of the twin boundaries (TBs) dropped, and the number of the twin lamellas was reduced. Under a very low heat input condition, the typical characteristics of thermomechanically affected zone (TMAZ) were discernible; however, the TMAZ was characterized by a recrystallized grain structure at higher heat input conditions. The grains in the heat-affected zone (HAZ) were slightly coarsened compared to those in the parent material (PM), but the grain size varied a little under different parameters. The hardness of the SZ increased as the heat input was increased, and the lowest hardness appeared at the HAZs where the welds failed. The ultimate tensile strength (UTS) was similar to that of the PM under various heat input conditions, but the yield strength (YS) and elongation were lower. The YS increased as the lowest hardness value increased, and the elongation decreased due to the enhanced strain localization.
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development of a fine grained microstructure and the properties of a nugget zone in friction stir welded Pure Copper
Scripta Materialia, 2007Co-Authors: Z Y, G Xie, L GengAbstract:Defect-free Pure Copper welds were achieved under low heat input conditions of 400–800 rpm for a traverse speed of 50 mm min−1. The grain size of the nugget zones decreased from 9 to 3.5 μm with decreasing rotation rate from 800 to 400 rpm. “Onion rings”, consisting of different-sized grain bands, were observed at 400 rpm, but disappeared at 600–800 rpm. Variations of both microhardness and yield strength of the nugget zones with grain size followed the Hall–Petch relationship.
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development of a fine grained microstructure and the properties of a nugget zone in friction stir welded Pure Copper
Scripta Materialia, 2007Co-Authors: Z Y, L GengAbstract:Defect-free Pure Copper welds were achieved under low heat input conditions of 400-800 rpm for a traverse speed of 50 mm min(-1). The grain size of the nugget zones decreased from 9 to 3.5 mu m with decreasing rotation rate from 800 to 400 rpm. "Onion rings", consisting of different-sized grain bands, were observed at 400 rpm, but disappeared at 600-800 rpm. Variations of both microhardness and yield strength of the nugget zones with grain size followed the Hall-Petch relationship. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
