The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Mohammad Kazem Besharati Givi - One of the best experts on this subject based on the ideXlab platform.
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on the role of pin geometry in microStructure and mechanical properties of aa7075 sic nano composite fabricated by friction stir welding technique
Materials & Design, 2014Co-Authors: Mohse Ahrami, Mohammad Kazem Besharati Givi, K Dehghani, Nade ParviAbstract:Abstract The main purpose of this research is to investigate the influence of pin geometry on the macroStructure, microStructure and mechanical properties of the friction stir welds, reinforced with SiC nano-particles. Toward this end, friction stir welding (FSW) conducted using five geometrically different pin tools. Other welding parameters were remained unchanged. Microstructural evaluation using optical microscopy (OM) and scanning electron microscopy (SEM) revealed a Banded Structure consisting of particle-rich and particle-free regions in stir zone (SZ). The most uniform particle distribution was found in the case of using threaded tapered pin tool. On the other hand, it was discovered that the reinforcements had severely accumulated in the SZ of specimen friction stir welded (FSWed) with four-flute cylindrical pin tool. Moreover, threaded tapered and four-flute cylindrical specimens showed the highest and the lowest microhardness, respectively. In spite of four-flute cylindrical specimen, other specimens failed in base metal during tensile testing. Besides, the highest ultimate tensile strength (UTS) was recorded for the specimen FSWed with triangular pin tool. Fracture surface of tensile specimens were also studied employing SEM technique.
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a novel approach to develop aluminum matrix nano composite employing friction stir welding technique
Materials & Design, 2014Co-Authors: Mohsen Bahrami, K Dehghani, Mohammad Kazem Besharati GiviAbstract:Abstract The main object of the present study is to investigate the effect of nano-sized SiC particle on the mechanical properties of the friction stir welding (FSW) joints. Prior to FSW, nano-sized SiC particles were incorporated into the joint line. A combination of three rotational speeds and three traveling speeds were applied. Microstructural evaluation using optical microscopy (OM) and scanning electron microscopy (SEM) revealed a Banded Structure consisting of particle-rich and particle-free regions in stir zone (SZ). The joints fabricated with rotational speed of 1250 rpm and traveling speeds of 40 and 50 mm/min, exhibited the highest mechanical properties. Owing to the presence of SiC nano-particles, at 1250 rpm and 40 mm/min, ultimate tensile strength (UTS) and percentage of elongation were improved by 31% and 76.1%, respectively. Significant increase in UTS and percentage of elongation were attributed to the pinning effect and increased nucleation sites associated with SiC nano-particles. Moreover, reinforcement particles resulted in breaking of primary grains. On the other hand, at 1250 rpm and 40 mm/min, SiC-included specimen showed superior ductility to SiC-free specimen. The fracture morphologies were in good agreement with corresponding ductility results.
K Dehghani - One of the best experts on this subject based on the ideXlab platform.
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on the role of pin geometry in microStructure and mechanical properties of aa7075 sic nano composite fabricated by friction stir welding technique
Materials & Design, 2014Co-Authors: Mohse Ahrami, Mohammad Kazem Besharati Givi, K Dehghani, Nade ParviAbstract:Abstract The main purpose of this research is to investigate the influence of pin geometry on the macroStructure, microStructure and mechanical properties of the friction stir welds, reinforced with SiC nano-particles. Toward this end, friction stir welding (FSW) conducted using five geometrically different pin tools. Other welding parameters were remained unchanged. Microstructural evaluation using optical microscopy (OM) and scanning electron microscopy (SEM) revealed a Banded Structure consisting of particle-rich and particle-free regions in stir zone (SZ). The most uniform particle distribution was found in the case of using threaded tapered pin tool. On the other hand, it was discovered that the reinforcements had severely accumulated in the SZ of specimen friction stir welded (FSWed) with four-flute cylindrical pin tool. Moreover, threaded tapered and four-flute cylindrical specimens showed the highest and the lowest microhardness, respectively. In spite of four-flute cylindrical specimen, other specimens failed in base metal during tensile testing. Besides, the highest ultimate tensile strength (UTS) was recorded for the specimen FSWed with triangular pin tool. Fracture surface of tensile specimens were also studied employing SEM technique.
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a novel approach to develop aluminum matrix nano composite employing friction stir welding technique
Materials & Design, 2014Co-Authors: Mohsen Bahrami, K Dehghani, Mohammad Kazem Besharati GiviAbstract:Abstract The main object of the present study is to investigate the effect of nano-sized SiC particle on the mechanical properties of the friction stir welding (FSW) joints. Prior to FSW, nano-sized SiC particles were incorporated into the joint line. A combination of three rotational speeds and three traveling speeds were applied. Microstructural evaluation using optical microscopy (OM) and scanning electron microscopy (SEM) revealed a Banded Structure consisting of particle-rich and particle-free regions in stir zone (SZ). The joints fabricated with rotational speed of 1250 rpm and traveling speeds of 40 and 50 mm/min, exhibited the highest mechanical properties. Owing to the presence of SiC nano-particles, at 1250 rpm and 40 mm/min, ultimate tensile strength (UTS) and percentage of elongation were improved by 31% and 76.1%, respectively. Significant increase in UTS and percentage of elongation were attributed to the pinning effect and increased nucleation sites associated with SiC nano-particles. Moreover, reinforcement particles resulted in breaking of primary grains. On the other hand, at 1250 rpm and 40 mm/min, SiC-included specimen showed superior ductility to SiC-free specimen. The fracture morphologies were in good agreement with corresponding ductility results.
Xiaochuan Zhang - One of the best experts on this subject based on the ideXlab platform.
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experimental investigation of fatigue crack growth behavior in Banded Structure of pipeline steel
Metals, 2020Co-Authors: Nan Zhan, Xiaochuan ZhangAbstract:The effect of a ferrite/mixed phase Banded Structure on the fatigue crack growth behavior of pipeline steel has been investigated in this work. Constant stress-controlled fatigue tests were carried out on unilateral notch specimens in the longitudinal direction (LD) and the transverse direction (TD). The strain accumulation was measured by digital image correlation (DIC) method and the fatigue fracture morphology was analyzed. The results show that the Banded Structure in the LD would cause a wide range of crack deflections, especially in the early stage of fatigue crack growth, which results in a lower fatigue crack growth rate compared to the TD. At the later stage, due to the increase of the plastic zone of the crack tip, more ferrite in the crack growth path of the TD specimen is also beneficial for crack tip blunting, thereby slowing down the increase of the crack growth rate.
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effect of ferrite pearlite Banded Structure on the local deformation and crack initiation at notches in pipeline steel
Engineering Fracture Mechanics, 2020Co-Authors: Xiaochuan Zhang, Yan Wang, Ning Guo, Yong Wang, Chenyang Zhang, Yingjie ZhuAbstract:Abstract The effect of ferrite/pearlite (F/P) Banded Structure on the local deformation and crack initiation of single-edge notched tension (SENT) pipeline steel specimen was investigated by digital image correlation (DIC) and uniaxial tensile tests under the microscope. The results show that the Banded distribution of the deformation field caused by F/P Banded Structure gradually disappears as the force increases and the strain concentration occurs at the shear band near the notch for each specimen. Micro cracks are prone to occur at the interface of F/P Banded Structure in 45° and TD specimens and the crack propagation path of the LD specimen is more tortuous. The effect of F/P Banded Structure on the maximum force and extension of SENT specimens are not obvious.
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the evolution of strain pattern induced by Banded Structure under uniaxial tension in low carbon microalloyed steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2019Co-Authors: Chunhua Ren, Xiaochuan Zhang, Yan Wang, Yan Guo, Huaiwen Wang, Yuyi ZhuAbstract:Abstract The presence of banding inhomogeneities is detrimental to the mechanical behaviors of steels due to the strain anisotropy. In this paper, combined with the in-situ tensile stage, digital image correlation (DIC) method was used to investigate the influence of banding pattern including the size, quantity and morphology on the continuous localized deformation and fracture behavior of low-carbon microalloyed steel under the uniaxial tension load. A zero-deformation test was introduced at the beginning of the experiment, where the accuracy and stability of DIC for this application were validated. The results show that the effect of Banded Structure on local deformation and damage evolution is significant. Compared to the rolling direction (RD) tensile, the local deformation of Banded Structure exhibits a higher sensitivity to the transverse direction (TD), and the development of shear bands is clearly affected by the local high strains caused by the deformation of soft banding. The coarse banding (CB) in specimen could decrease the mechanical properties of material. Meanwhile, the mechanical anisotropy is explained by the evolution model of local deformation. This work is helpful to understand the effect of Banded Structure on the mechanical behavior of steel.
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deformation analysis of ferrite pearlite Banded Structure under uniaxial tension using digital image correlation
Optics and Lasers in Engineering, 2016Co-Authors: Xiaochuan Zhang, Yong Wang, Chunhua Ren, Jia Yang, Zhixia Qiao, Cheng ChenAbstract:Abstract The ferrite/pearlite Banded Structure causes the anisotropic behavior of steel. In this paper, digital image correlation (DIC) was used to analyze the micro deformation of this microStructure under uniaxial tension. The reliability of DIC for this application was verified by a zero-deformation experiment. The results show that the performance of DIC can satisfy the requirements of the tensile deformation measurement. Then, two uniaxial tensile tests in different directions (longitudinal direction and transverse direction) were carried out and DIC was used to measure the micro deformation of the ferrite/pearlite Banded Structure. The measured results show that the ferrite bands undergo the main deformation in the transverse tension, which results in the relatively weaker tensile properties in the transverse direction than in the longitudinal direction. This work is useful to guide the modification of the bands morphology and extend the application scope of DIC.
Nade Parvi - One of the best experts on this subject based on the ideXlab platform.
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on the role of pin geometry in microStructure and mechanical properties of aa7075 sic nano composite fabricated by friction stir welding technique
Materials & Design, 2014Co-Authors: Mohse Ahrami, Mohammad Kazem Besharati Givi, K Dehghani, Nade ParviAbstract:Abstract The main purpose of this research is to investigate the influence of pin geometry on the macroStructure, microStructure and mechanical properties of the friction stir welds, reinforced with SiC nano-particles. Toward this end, friction stir welding (FSW) conducted using five geometrically different pin tools. Other welding parameters were remained unchanged. Microstructural evaluation using optical microscopy (OM) and scanning electron microscopy (SEM) revealed a Banded Structure consisting of particle-rich and particle-free regions in stir zone (SZ). The most uniform particle distribution was found in the case of using threaded tapered pin tool. On the other hand, it was discovered that the reinforcements had severely accumulated in the SZ of specimen friction stir welded (FSWed) with four-flute cylindrical pin tool. Moreover, threaded tapered and four-flute cylindrical specimens showed the highest and the lowest microhardness, respectively. In spite of four-flute cylindrical specimen, other specimens failed in base metal during tensile testing. Besides, the highest ultimate tensile strength (UTS) was recorded for the specimen FSWed with triangular pin tool. Fracture surface of tensile specimens were also studied employing SEM technique.
Hidetoshi Fujii - One of the best experts on this subject based on the ideXlab platform.
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Banded Structure and its distribution in friction stir processing of 316l austenitic stainless steel
Journal of Nuclear Materials, 2012Co-Authors: Y C Chen, Hidetoshi Fujii, Takuya Tsumura, Yoshihiko Kitagawa, Kazuhiro Nakata, Kenji Ikeuchi, K Matsubayashi, Yukio Michishita, Yasuyuki Fujiya, J KatohAbstract:Abstract Banded Structures, which vary with welding parameters, were observed in friction stir processing of 316L austenite stainless steel. Sigma phase precipitation was detected in Banded Structures by transmission electron microscopy. The amount of Banded Structure had direct ratio relations with heat input. The higher the heat input, the larger the area of Banded Structures. This is attributable to slower cooling rate at high heat input, which results in longer exposure to the temperature range for precipitation. The formation of sigma phase produced Cr depletion, which resulted in largely degraded corrosion resistance. The present study suggests that low heat input (i.e. low rotation speeds, low working loads and high welding speed) contributes to restrain sigma phase precipitation.
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the effect of sic particles on the microStructure and mechanical properties of friction stir welded pure copper joints
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: Yufeng Sun, Hidetoshi FujiiAbstract:Abstract The SiC particles with mean size of 5 μm were introduced into the pure Cu joints during the friction stir welding process. After one pass processing, the distribution of SiC particle is not uniform and some pores formed around the aggregation of SiC particles. However, the particle distribution became rather uniform after two passes processing and the previous pores can be refilled. In addition, Banded Structure consisting of particle-rich and particle-free region can be observed in the stir zone. The particle-rich region has an average grain size of less than 2 μm, much smaller than that of about 8 μm in the particle-free region. Microstructural observation confirmed that the SiC particles can act as the heterogeneous nucleation site in the dynamic recrystallization of Cu grains. The SiC dispersed Cu joints exhibit a Vickers hardness of 110 HV, much higher than 70 HV in the stir zone without SiC particles.
