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Ali Nazari - One of the best experts on this subject based on the ideXlab platform.
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application of artificial neural networks for analytical modeling of charpy Impact Energy of functionally graded steels
Neural Computing and Applications, 2013Co-Authors: Ali NazariAbstract:In the present study, the Charpy Impact Energy of ferritic and austenitic functionally graded steel produced by electroslag remelting has been modeled in crack divider configuration. To produce functionally graded steels, two slices of plain carbon steel and austenitic stainless steels were spot welded and used as electroslag remelting electrode. Functionally graded steel containing graded layers of ferrite and austenite may be fabricated via diffusion of alloying elements during remelting stage. Vickers microhardness profile of the specimen has been obtained experimentally and modeled with artificial neural networks. To build the model for graded ferritic and austenitic steels, training, testing and validation using, respectively, 174 and 120 experimental data were conducted. According to the input parameters, in the neural networks model, the Vickers microhardness of each layer was predicted. A good fit equation that correlates the Vickers microhardness of each layer to its corresponding chemical composition was achieved by the optimized network for both ferritic and austenitic graded steels. Afterward, the Vickers microhardness of each layer in functionally graded steels was related to the yield stress of the corresponding layer and by assuming Holloman relation for stress–strain curve of each layer, the area under each stress–strain curve was acquired. Finally, by applying the rule of mixtures, Charpy Impact Energy of functionally graded steels in crack divider configuration was found through numerical method. The obtained results from the proposed model are in good agreement with those acquired from the experiments.
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application of strain gradient plasticity theory to model charpy Impact Energy of functionally graded steels using modified stress strain curve data
Computational Materials Science, 2012Co-Authors: Ali NazariAbstract:Abstract Functionally graded ferritic and austenitic steels were produced through electroslag refining by setting the austenitic and carbon steels with appropriate thickness as electrode. Charpy Impact Energy of the specimen has been studied and modeled regarding the mechanism-based strain gradient plasticity theory. The hardness of each layer was related to the density of the dislocations of that layer and then by using a linear relation, the predicted hardness was related to its corresponding yield stress. Afterwards; by assuming Holloman relation for the corresponding stress–strain curves, tensile strengths and tensile strains of the constituent layer were determined via numerical method. By using load–displacement curves acquired from instrumented Charpy Impact tests on primary specimens, the obtained stress–strain curves from uniaxial tensile tests were modified. Charpy Impact Energy each layer was related to the corresponding area under modified stress–strain curve of that layer and finally by applying the rule of mixtures, Charpy Impact Energy of functionally graded steels was determined. The obtained results of the proposed model are in good agreement with the experimental ones.
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modeling Impact Energy of functionally graded steels in crack divider configuration using modified stress strain curve data
International Journal of Damage Mechanics, 2012Co-Authors: Ali Nazari, Jamshid Aghazadeh Mohandesi, Shadi RiahiAbstract:Charpy Impact Energy of functionally graded steels produced by elec- troslag remelting composed of graded ferritic and austenitic layers together with bainite or martensite intermediate layer in crack divider configuration has been modeled. From loaddisplacement curves acquired from instrumented Charpy Impact test for original ferritic and original austenitic steels together with single- phase bainitic and martensitic specimens, the obtained stressstrain curves from uniaxial tensile tests were modified. Afterward, Charpy Impact Energy of each con- stituent layer was assumed to be proportional to the area under modified stressstrain curve and Charpy Impact Energy of the functionally graded composites was determined analytically through the rule of mixtures. A good agreement between experimental results and the results obtained from analytical model was observed.
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simulation charpy Impact Energy of functionally graded steels by modified stress strain curve through mechanism based strain gradient plasticity theory
Computational Materials Science, 2012Co-Authors: Ali NazariAbstract:Abstract In the present work, Charpy Impact Energy of functionally graded steels produced by electroslag remelting composed of graded ferritic or austenitic layers in both crack divider and crack arrester configurations has been modeled by finite element method. The yield stress of each layer was related to the density of the statistically stored dislocations of that layer and assuming by Holloman relation for the corresponding stress–strain curves, tensile strengths of the constituent layers were determined via numerical method. By using load–displacement curves acquired from instrumented Charpy Impact tests on primary specimens, the obtained stress–strain curves from uniaxial tensile tests were modified. The data used for each layer in finite element modeling were predicted modified stress–strain curves obtained from strain gradient plasticity theory. A relatively good agreement between experimental results and those obtained from simulation was observed.
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modeling charpy Impact Energy of functionally graded steel based on the strain gradient plasticity theory and modified stress strain curve data
Computational Materials Science, 2011Co-Authors: Ali NazariAbstract:Abstract Functionally graded ferritic and austenitic steels were produced through electroslag refining by setting the austenitic and carbon steels with appropriate thickness as electrode. Charpy Impact Energy of the specimen has been studied and modeled regarding the mechanism-based strain gradient plasticity theory. The yield stress of each layer was related to the density of the statistically stored dislocations of that layer and assuming Holloman relation for the corresponding stress–strain curves, tensile strengths of the constituent layer were determined via numerical method. By using load–displacement curves acquired from instrumented Charpy Impact tests on primary specimens, the obtained stress–strain curves from uniaxial tensile tests were modified. Charpy Impact Energy of each layer was related to the corresponding area under its modified stress–strain curve and finally by applying the rule of mixtures, Charpy Impact Energy of functionally graded steels was determined. The obtained results of the proposed model are in good agreement with the experimental ones.
Y J Chao - One of the best experts on this subject based on the ideXlab platform.
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correlations between charpy v notch Impact Energy and fracture toughness of nuclear reactor pressure vessel rpv steels
Engineering Fracture Mechanics, 2015Co-Authors: Meifang Yu, Y J ChaoAbstract:Abstract Correlations between Charpy V-notch (CVN) Impact Energy and fracture toughness are of great practical significance for reactor pressure vessel (RPV) structural integrity assessment. In this paper, correlations between the two for three commonly used RPV steels, namely Chinese A508-3 steel, USA A533B steel, Euro 20MnMoNi55 steel, are investigated with both a direct conversion and the Master Curve method. It is found that fracture toughness can be well predicted from CVN Impact Energy through reference temperature T0 of the Master Curve method. Five predicted T0 values from different correlations are close to the T0 from actual test. The mean value of the five T0 values provides a good estimate for the fracture toughness in the transition region.
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correlations between charpy v notch Impact Energy and fracture toughness of nuclear reactor pressure vessel rpv steels
ASME 2015 Pressure Vessels and Piping Conference, 2015Co-Authors: Meifang Yu, Y J ChaoAbstract:Both Charpy V-notch (CVN) Impact Energy and fracture toughness are parameters reflecting toughness of the material. Charpy tests are however easy to perform compared to standard fracture toughness tests, especially when the material is irradiated and quantity is limited. Correlations between the two parameters are therefore of great significance, especially for reactor pressure vessel (RPV) structural integrity assessment. In this paper, correlations between CVN Impact Energy and fracture toughness of three commonly used RPV steels, namely Chinese A508-3 steel, USA A533B steel, Euro 20MnMoNi55 steel, are investigated with two methods. One method applies a direct conversion using empirical formulas and the other adopts the Master Curve method. It is found that when the empirical formula is used, the difference between the predicted fracture toughness (from the CVN Impact Energy) and actual test data is relatively small in upper shelf, lower shelf and the bottom of transition region, while relatively large in other parts of the transition region. When the Master Curve method is adopted, whether the reference temperature T0 is estimated through temperature at 28J or 41J CVN Impact Energy, the predicted fracture toughness values of the three steels are consistent with actual test data. The reference temperature T0 is also estimated through the IGC-parameter correlation and through a combination of empirical formula and multi-temperature method. Both procedures show excellent agreement with test results. The mean value of T0 estimated from T28J, T41J, IGC-parameters and the combination method is denoted by TQ-ave and is then used as the final reference temperature T0 for the Master Curve determination. Accuracy of TQ-ave (and therefore the Master Curve method) is demonstrated by comparison with actual test data of the three RPV steels. It is concluded that Master Curve method provides a reliable procedure for predicting fracture toughness in the transition region utilizing limited CVN Impact Energy data from open literature.Copyright © 2015 by ASME
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charpy Impact Energy fracture toughness and ductile brittle transition temperature of dual phase 590 steel
Materials & Design, 2007Co-Authors: Y J Chao, J D Ward, R G SandsAbstract:Abstract Advanced high strength steels (AHSS) have been introduced and gradually adopted in vehicle structures as lightweight materials in the past years. Engineering performance of AHSS in many areas have shown that they are superior to the conventional steels. In this paper, we present the results from Charpy V-Notch Impact tests on dual phase 590 (DP590) steel, which belongs to the family of AHSS. Tests were conducted at temperatures ranging from −120 °C (−184 °F) to 90 °C (194 °F). Specimens oriented in both L–T and T–L directions were tested. Due to its reduced thickness relative to the ASTM testing standards, specimens from a medium low carbon steel AISI-1018, having both standard and reduced thickness, were tested as well to justify the correction method for the DP590 data. The results show that the ductile–brittle transition temperature (DBTT) based on 20.4 J (15 ft-lb) absorbed Energy is about −95 °C (−139 °F) for DP590 which is far below the 5 °C (41 °F) of the AISI-1018 steel. In addition, fracture toughness values of DP590 steel were obtained from correlation with the Charpy Impact Energy. It is shown that that the fracture toughness of DP590 is in the range of 160–200 MPa m 1/2 (146–182 ksi in. 1/2 ) in the upper shelf region, which includes the room temperature.
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charpy Impact Energy fracture toughness and ductile brittle transition temperature of dual phase 590 steel
Materials & Design, 2007Co-Authors: Y J Chao, J D Ward, R G SandsAbstract:Abstract Advanced high strength steels (AHSS) have been introduced and gradually adopted in vehicle structures as lightweight materials in the past years. Engineering performance of AHSS in many areas have shown that they are superior to the conventional steels. In this paper, we present the results from Charpy V-Notch Impact tests on dual phase 590 (DP590) steel, which belongs to the family of AHSS. Tests were conducted at temperatures ranging from −120 °C (−184 °F) to 90 °C (194 °F). Specimens oriented in both L–T and T–L directions were tested. Due to its reduced thickness relative to the ASTM testing standards, specimens from a medium low carbon steel AISI-1018, having both standard and reduced thickness, were tested as well to justify the correction method for the DP590 data. The results show that the ductile–brittle transition temperature (DBTT) based on 20.4 J (15 ft-lb) absorbed Energy is about −95 °C (−139 °F) for DP590 which is far below the 5 °C (41 °F) of the AISI-1018 steel. In addition, fracture toughness values of DP590 steel were obtained from correlation with the Charpy Impact Energy. It is shown that that the fracture toughness of DP590 is in the range of 160–200 MPa m 1/2 (146–182 ksi in. 1/2 ) in the upper shelf region, which includes the room temperature.
Gustavo Garcia - One of the best experts on this subject based on the ideXlab platform.
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total electron scattering cross sections from thiophene for the 1 300 ev Impact Energy range
Journal of Chemical Physics, 2018Co-Authors: A I Lozano, Alexandra Loupas, Francisco J Blanco, J D Gorfinkiel, Gustavo GarciaAbstract:Experimental electron scattering cross sections for thiophene in the Impact Energy range from 1 to 300 eV have been measured with a magnetically confined electron transmission-beam apparatus. Random uncertainty limits have been estimated to be less than 5%, and systematic errors derived from acceptance angle limitations have also been identified and evaluated. Experimental values are compared with our previous low Energy (1-15 eV) R-matrix and intermediate/high Energy (15-300 eV) IAM-SCAR+I calculations finding reasonable agreement, within the combined uncertainty limits. Some of the low Energy shape and core-excited resonances predicted by previous calculations are experimentally confirmed in this study.
A I Lozano - One of the best experts on this subject based on the ideXlab platform.
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total electron scattering cross sections from thiophene for the 1 300 ev Impact Energy range
Journal of Chemical Physics, 2018Co-Authors: A I Lozano, Alexandra Loupas, Francisco J Blanco, J D Gorfinkiel, Gustavo GarciaAbstract:Experimental electron scattering cross sections for thiophene in the Impact Energy range from 1 to 300 eV have been measured with a magnetically confined electron transmission-beam apparatus. Random uncertainty limits have been estimated to be less than 5%, and systematic errors derived from acceptance angle limitations have also been identified and evaluated. Experimental values are compared with our previous low Energy (1-15 eV) R-matrix and intermediate/high Energy (15-300 eV) IAM-SCAR+I calculations finding reasonable agreement, within the combined uncertainty limits. Some of the low Energy shape and core-excited resonances predicted by previous calculations are experimentally confirmed in this study.
R G Sands - One of the best experts on this subject based on the ideXlab platform.
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charpy Impact Energy fracture toughness and ductile brittle transition temperature of dual phase 590 steel
Materials & Design, 2007Co-Authors: Y J Chao, J D Ward, R G SandsAbstract:Abstract Advanced high strength steels (AHSS) have been introduced and gradually adopted in vehicle structures as lightweight materials in the past years. Engineering performance of AHSS in many areas have shown that they are superior to the conventional steels. In this paper, we present the results from Charpy V-Notch Impact tests on dual phase 590 (DP590) steel, which belongs to the family of AHSS. Tests were conducted at temperatures ranging from −120 °C (−184 °F) to 90 °C (194 °F). Specimens oriented in both L–T and T–L directions were tested. Due to its reduced thickness relative to the ASTM testing standards, specimens from a medium low carbon steel AISI-1018, having both standard and reduced thickness, were tested as well to justify the correction method for the DP590 data. The results show that the ductile–brittle transition temperature (DBTT) based on 20.4 J (15 ft-lb) absorbed Energy is about −95 °C (−139 °F) for DP590 which is far below the 5 °C (41 °F) of the AISI-1018 steel. In addition, fracture toughness values of DP590 steel were obtained from correlation with the Charpy Impact Energy. It is shown that that the fracture toughness of DP590 is in the range of 160–200 MPa m 1/2 (146–182 ksi in. 1/2 ) in the upper shelf region, which includes the room temperature.
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charpy Impact Energy fracture toughness and ductile brittle transition temperature of dual phase 590 steel
Materials & Design, 2007Co-Authors: Y J Chao, J D Ward, R G SandsAbstract:Abstract Advanced high strength steels (AHSS) have been introduced and gradually adopted in vehicle structures as lightweight materials in the past years. Engineering performance of AHSS in many areas have shown that they are superior to the conventional steels. In this paper, we present the results from Charpy V-Notch Impact tests on dual phase 590 (DP590) steel, which belongs to the family of AHSS. Tests were conducted at temperatures ranging from −120 °C (−184 °F) to 90 °C (194 °F). Specimens oriented in both L–T and T–L directions were tested. Due to its reduced thickness relative to the ASTM testing standards, specimens from a medium low carbon steel AISI-1018, having both standard and reduced thickness, were tested as well to justify the correction method for the DP590 data. The results show that the ductile–brittle transition temperature (DBTT) based on 20.4 J (15 ft-lb) absorbed Energy is about −95 °C (−139 °F) for DP590 which is far below the 5 °C (41 °F) of the AISI-1018 steel. In addition, fracture toughness values of DP590 steel were obtained from correlation with the Charpy Impact Energy. It is shown that that the fracture toughness of DP590 is in the range of 160–200 MPa m 1/2 (146–182 ksi in. 1/2 ) in the upper shelf region, which includes the room temperature.
