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A K Bhaduri - One of the best experts on this subject based on the ideXlab platform.
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effect of deformation temperature on the ductile Brittle Transition behavior of a modified 9cr 1mo steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2015Co-Authors: Arya Chatterjee, Debalay Chakrabarti, R Mitra, A K BhaduriAbstract:Abstract A modified 9Cr–1Mo steel received in normalized and tempered condition has been subjected to four different hot-rolling treatments at different rolling temperatures (1050 °C, 1000 °C, 950 °C and 875 °C) applying a constant true strain of ~0.7. The rolled plates were tempered and tested for tensile and Charpy impact properties following standard procedures. Hot-rolling increased the strength by more than 100 MPa, but reduced the ductility of the steel by more than 10%. The ductile-to-Brittle Transition temperature (DBTT) was found to increase by more than 25 °C after hot-rolling as compared to As-received steel. Among the rolled samples, the plates rolled at 950 °C and 1050 °C showed higher upper shelf energy (comparable to As-received steel), whilst the plate rolled at 1050 °C showed the lowest DBTT. In terms of superior strength–toughness combination rolling at 1050 °C can be considered to be optimum. The results have been analyzed considering the effect of rolling on parameters related to the microstructure and crystallographic texture of the steel, such as, effective grain size, ferrite fraction, fraction of low-angle boundaries, fraction of cleavage planes on the main fracture plane and the fraction of slip planes along the 45° to the main fracture plane.
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effect of normalization temperatures on ductile Brittle Transition temperature of a modified 9cr 1mo steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2014Co-Authors: Arya Chatterjee, Debalay Chakrabarti, R Mitra, A K BhaduriAbstract:Abstract A modified 9Cr–1Mo steel has been exposed to three separate normalization treatments i.e. at 950 °C, 1025 °C and 1100 °C from As-received (normalized at 1050 °C and tempered at 750 °C) condition. After subsequent tempering treatment the impact toughness in terms of upper shelf energy (USE) and ductile-to-Brittle Transition temperature (DBTT) has been evaluated using Charpy impact testing (with 10 mm×10 mm×55 mm specimens) following ASTM E23 procedures. A substantial improvement in USE (~20 J) and reduction in DBTT (~20 °C) has been noticed for the 1025 °C treatment. The result has been analysed in terms of change in yield strength and ductility evaluated with tensile tests. Further, effects of microstructure, precipitate and texture on the change of DBTT have been studied with TEM and EBSD analyses. The results have been attributed to the smaller ‘effective grain size’, higher fraction of high-angle boundaries, presence of beneficial γ-fibre texture and dissolution of the pre-existing coarse precipitates in the reheated sample as compared to As-received material.
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a study of fracture mechanisms in rafm steel in the ductile to Brittle Transition temperature regime
Procedia Engineering, 2014Co-Authors: Arup Dasgupta, Rajendra E Kumar, S Saroja, S Sathyanarayanan, G Sasikala, S K Albert, A K Bhaduri, T. JayakumarAbstract:Abstract The fracture behaviour of a Reduced Activation Ferritic Martensitic Steel (RAFM) has been studied within the Ductile to Brittle Transition Temperature (DBTT) regime. The DBTT has been determined by ASTM E 1921 based reference temperature approach under dynamic loading condition. The dynamic reference temperature (T0dy) was found to be − 33.8 °C. The fracture mechanism has been studied by extracting TEM specimens precisely at the crack initiation sites using focused ion beam (FIB) technique in a high resolution dual beam scanning electron microscope. Detailed analytical TEM studies revealed that the morphology of carbides play a crucial role in the initiation of a crack. The larger ellipsoidal carbides, which were found to be Cr-rich, have been found to be responsible for dislocation piles ups. The shorter edge of these ellipsoidal carbides are areas of high stress concentration and were found to initiate cracks by decohesion of the particle-matrix interface. On the contrary, the iron rich carbides have been found to be smaller, more spherical, and thus less effective in blocking dislocation movement and therefore formation of pile ups. The results, which reveal an important mechanism towards crack initiation in ferritic-martensitic steels, will be presented in detail.
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.
Amir Ali Milani - One of the best experts on this subject based on the ideXlab platform.
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Modeling ductile to Brittle Transition temperature of functionally graded steels by ANFIS
Applied Mathematical Modelling, 2012Co-Authors: Ali Nazari, Amir Ali Milani, Gholamreza KhalajAbstract:Abstract In the present paper, a model based on adaptive network-based fuzzy inference systems (ANFIS) for predicting ductile to Brittle Transition temperature of functionally graded steels in both crack divider and crack arrester configurations has been presented. Functionally graded steels containing graded ferritic and austenitic regions together with bainite and martensite intermediate layers were produced by electroslag remelting. To build the model, training and testing using experimental results from 140 specimens were conducted. The used data as inputs in ANFIS models are arranged in a format of six parameters that cover the FGS type, the crack tip configuration, the thickness of graded ferritic region, the thickness of graded austenitic region, the distance of the notch from bainite or martensite intermediate layer and temperature. According to these input parameters, in the ANFIS models, the ductile to Brittle Transition temperature of each FGS specimen was predicted. The training and testing results in the ANFIS models have shown a strong potential for predicting the ductile to Brittle Transition temperature of each FGS specimen.
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Modeling ductile to Brittle Transition temperature of functionally graded steels by fuzzy logic
Journal of Materials Science, 2011Co-Authors: Ali Nazari, Amir Ali MilaniAbstract:In this article, a model based on fuzzy logic (FL) for predicting ductile to Brittle Transition temperature of functionally graded steels in both crack divider and crack arrester configurations has been presented. Functionally graded steels containing graded ferritic and austenitic regions together with bainite and martensite intermediate layers were produced by electroslag remelting. For purpose of building the model, training and testing using experimental results from 140 specimens produced from two basic composites were conducted. The used data as inputs in FL models are arranged in a format of six input parameters that cover the FGS type, the crack tip configuration, the thickness of graded ferritic region, the thickness of graded austenitic region, the distance of the notch from bainite or martensite intermediate layer, and temperature. According to these input parameters, in the FL, the ductile to Brittle Transition temperature of each FGS specimen was predicted. It has been found that FL model will be valid within the ranges of variables. The training and testing results in the FL model have shown a strong potential for predicting the ductile to Brittle Transition temperature of each FGS specimen.
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retraction note to modeling ductile to Brittle Transition temperature of functionally graded steels by fuzzy logic
Journal of Materials Science, 2011Co-Authors: Ali Nazari, Amir Ali MilaniAbstract:In this article, a model based on fuzzy logic (FL) for predicting ductile to Brittle Transition temperature of functionally graded steels in both crack divider and crack arrester configurations has been presented. Functionally graded steels containing graded ferritic and austenitic regions together with bainite and martensite intermediate layers were produced by electroslag remelting. For purpose of building the model, training and testing using experimental results from 140 specimens produced from two basic composites were conducted. The used data as inputs in FL models are arranged in a format of six input parameters that cover the FGS type, the crack tip configuration, the thickness of graded ferritic region, the thickness of graded austenitic region, the distance of the notch from bainite or martensite intermediate layer, and temperature. According to these input parameters, in the FL, the ductile to Brittle Transition temperature of each FGS specimen was predicted. It has been found that FL model will be valid within the ranges of variables. The training and testing results in the FL model have shown a strong potential for predicting the ductile to Brittle Transition temperature of each FGS specimen.
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Modeling Ductile-to-Brittle Transition Temperature of Functionally Graded Steels by Gene Expression Programming
International Journal of Damage Mechanics, 2011Co-Authors: Amir Ali Milani, Ali NazariAbstract:In this article, a model based on gene expression programming for pre- dicting ductile-to-Brittle Transition temperature of functionally graded steels in both crack divider and crack arrester configurations has been presented. Functionally, graded steels containing graded ferritic and austenitic regions together with bainite and martensite intermediate layers were produced by electroslag remelting. For the purpose of building the model, training and testing using experimental results from 140 specimens produced from two basic composites were conducted. The data used as input in gene expression programming models are arranged in a format of six parameters that cover the FGS type, the crack tip configuration, the thickness of graded ferritic region, the thickness of graded austenitic region, the distance of the notch from bainite or martensite intermediate layer, and temperature. According to these input parameters, in the gene expression programming, the ductile-to-Brittle Transition temperature of each FGS specimen was predicted. The training and testing results in the gene expression programming model have shown strong potential for predicting the ductile-to-Brittle Transition temperature of each FGS specimens.
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Modeling ductile to Brittle Transition temperature of functionally graded steels by artificial neural networks
Computational Materials Science, 2011Co-Authors: Ali Nazari, Amir Ali Milani, Mahnaz ZakeriAbstract:In the present paper, a model based on artificial neural networks for predicting ductile to Brittle Transition temperature of functionally graded steels in both crack divider and crack arrester configurations has been presented. Functionally graded steels containing graded ferritic and austenitic regions together with bainite and martensite intermediate layers were produced by electroslag remelting. To build the model, training and testing were conducted using experimental results from 140 specimens produced of two basic composites. The utilized data in the multilayer feed forward neural networks models are arranged in a format of six input parameters that cover the specimen type, the crack tip configuration, the thickness of graded ferritic region, the thickness of graded austenitic region, the distance of the notch from bainite or martensite intermediate layer and temperature. According to these input parameters, in the neural networks models, the ductile to Brittle Transition temperature of each specimen was predicted. The training and testing results in the neural network model have shown a strong potential for predicting the ductile to Brittle Transition temperature of each specimen.
Ali Nazari - One of the best experts on this subject based on the ideXlab platform.
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Modeling ductile to Brittle Transition temperature of functionally graded steels by ANFIS
Applied Mathematical Modelling, 2012Co-Authors: Ali Nazari, Amir Ali Milani, Gholamreza KhalajAbstract:Abstract In the present paper, a model based on adaptive network-based fuzzy inference systems (ANFIS) for predicting ductile to Brittle Transition temperature of functionally graded steels in both crack divider and crack arrester configurations has been presented. Functionally graded steels containing graded ferritic and austenitic regions together with bainite and martensite intermediate layers were produced by electroslag remelting. To build the model, training and testing using experimental results from 140 specimens were conducted. The used data as inputs in ANFIS models are arranged in a format of six parameters that cover the FGS type, the crack tip configuration, the thickness of graded ferritic region, the thickness of graded austenitic region, the distance of the notch from bainite or martensite intermediate layer and temperature. According to these input parameters, in the ANFIS models, the ductile to Brittle Transition temperature of each FGS specimen was predicted. The training and testing results in the ANFIS models have shown a strong potential for predicting the ductile to Brittle Transition temperature of each FGS specimen.
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Modeling ductile to Brittle Transition temperature of functionally graded steels by fuzzy logic
Journal of Materials Science, 2011Co-Authors: Ali Nazari, Amir Ali MilaniAbstract:In this article, a model based on fuzzy logic (FL) for predicting ductile to Brittle Transition temperature of functionally graded steels in both crack divider and crack arrester configurations has been presented. Functionally graded steels containing graded ferritic and austenitic regions together with bainite and martensite intermediate layers were produced by electroslag remelting. For purpose of building the model, training and testing using experimental results from 140 specimens produced from two basic composites were conducted. The used data as inputs in FL models are arranged in a format of six input parameters that cover the FGS type, the crack tip configuration, the thickness of graded ferritic region, the thickness of graded austenitic region, the distance of the notch from bainite or martensite intermediate layer, and temperature. According to these input parameters, in the FL, the ductile to Brittle Transition temperature of each FGS specimen was predicted. It has been found that FL model will be valid within the ranges of variables. The training and testing results in the FL model have shown a strong potential for predicting the ductile to Brittle Transition temperature of each FGS specimen.
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retraction note to modeling ductile to Brittle Transition temperature of functionally graded steels by fuzzy logic
Journal of Materials Science, 2011Co-Authors: Ali Nazari, Amir Ali MilaniAbstract:In this article, a model based on fuzzy logic (FL) for predicting ductile to Brittle Transition temperature of functionally graded steels in both crack divider and crack arrester configurations has been presented. Functionally graded steels containing graded ferritic and austenitic regions together with bainite and martensite intermediate layers were produced by electroslag remelting. For purpose of building the model, training and testing using experimental results from 140 specimens produced from two basic composites were conducted. The used data as inputs in FL models are arranged in a format of six input parameters that cover the FGS type, the crack tip configuration, the thickness of graded ferritic region, the thickness of graded austenitic region, the distance of the notch from bainite or martensite intermediate layer, and temperature. According to these input parameters, in the FL, the ductile to Brittle Transition temperature of each FGS specimen was predicted. It has been found that FL model will be valid within the ranges of variables. The training and testing results in the FL model have shown a strong potential for predicting the ductile to Brittle Transition temperature of each FGS specimen.
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Modeling Ductile-to-Brittle Transition Temperature of Functionally Graded Steels by Gene Expression Programming
International Journal of Damage Mechanics, 2011Co-Authors: Amir Ali Milani, Ali NazariAbstract:In this article, a model based on gene expression programming for pre- dicting ductile-to-Brittle Transition temperature of functionally graded steels in both crack divider and crack arrester configurations has been presented. Functionally, graded steels containing graded ferritic and austenitic regions together with bainite and martensite intermediate layers were produced by electroslag remelting. For the purpose of building the model, training and testing using experimental results from 140 specimens produced from two basic composites were conducted. The data used as input in gene expression programming models are arranged in a format of six parameters that cover the FGS type, the crack tip configuration, the thickness of graded ferritic region, the thickness of graded austenitic region, the distance of the notch from bainite or martensite intermediate layer, and temperature. According to these input parameters, in the gene expression programming, the ductile-to-Brittle Transition temperature of each FGS specimen was predicted. The training and testing results in the gene expression programming model have shown strong potential for predicting the ductile-to-Brittle Transition temperature of each FGS specimens.
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Modeling ductile to Brittle Transition temperature of functionally graded steels by artificial neural networks
Computational Materials Science, 2011Co-Authors: Ali Nazari, Amir Ali Milani, Mahnaz ZakeriAbstract:In the present paper, a model based on artificial neural networks for predicting ductile to Brittle Transition temperature of functionally graded steels in both crack divider and crack arrester configurations has been presented. Functionally graded steels containing graded ferritic and austenitic regions together with bainite and martensite intermediate layers were produced by electroslag remelting. To build the model, training and testing were conducted using experimental results from 140 specimens produced of two basic composites. The utilized data in the multilayer feed forward neural networks models are arranged in a format of six input parameters that cover the specimen type, the crack tip configuration, the thickness of graded ferritic region, the thickness of graded austenitic region, the distance of the notch from bainite or martensite intermediate layer and temperature. According to these input parameters, in the neural networks models, the ductile to Brittle Transition temperature of each specimen was predicted. The training and testing results in the neural network model have shown a strong potential for predicting the ductile to Brittle Transition temperature of each specimen.
Arya Chatterjee - One of the best experts on this subject based on the ideXlab platform.
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effect of deformation temperature on the ductile Brittle Transition behavior of a modified 9cr 1mo steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2015Co-Authors: Arya Chatterjee, Debalay Chakrabarti, R Mitra, A K BhaduriAbstract:Abstract A modified 9Cr–1Mo steel received in normalized and tempered condition has been subjected to four different hot-rolling treatments at different rolling temperatures (1050 °C, 1000 °C, 950 °C and 875 °C) applying a constant true strain of ~0.7. The rolled plates were tempered and tested for tensile and Charpy impact properties following standard procedures. Hot-rolling increased the strength by more than 100 MPa, but reduced the ductility of the steel by more than 10%. The ductile-to-Brittle Transition temperature (DBTT) was found to increase by more than 25 °C after hot-rolling as compared to As-received steel. Among the rolled samples, the plates rolled at 950 °C and 1050 °C showed higher upper shelf energy (comparable to As-received steel), whilst the plate rolled at 1050 °C showed the lowest DBTT. In terms of superior strength–toughness combination rolling at 1050 °C can be considered to be optimum. The results have been analyzed considering the effect of rolling on parameters related to the microstructure and crystallographic texture of the steel, such as, effective grain size, ferrite fraction, fraction of low-angle boundaries, fraction of cleavage planes on the main fracture plane and the fraction of slip planes along the 45° to the main fracture plane.
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effect of normalization temperatures on ductile Brittle Transition temperature of a modified 9cr 1mo steel
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2014Co-Authors: Arya Chatterjee, Debalay Chakrabarti, R Mitra, A K BhaduriAbstract:Abstract A modified 9Cr–1Mo steel has been exposed to three separate normalization treatments i.e. at 950 °C, 1025 °C and 1100 °C from As-received (normalized at 1050 °C and tempered at 750 °C) condition. After subsequent tempering treatment the impact toughness in terms of upper shelf energy (USE) and ductile-to-Brittle Transition temperature (DBTT) has been evaluated using Charpy impact testing (with 10 mm×10 mm×55 mm specimens) following ASTM E23 procedures. A substantial improvement in USE (~20 J) and reduction in DBTT (~20 °C) has been noticed for the 1025 °C treatment. The result has been analysed in terms of change in yield strength and ductility evaluated with tensile tests. Further, effects of microstructure, precipitate and texture on the change of DBTT have been studied with TEM and EBSD analyses. The results have been attributed to the smaller ‘effective grain size’, higher fraction of high-angle boundaries, presence of beneficial γ-fibre texture and dissolution of the pre-existing coarse precipitates in the reheated sample as compared to As-received material.