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V Satya V Prasad - One of the best experts on this subject based on the ideXlab platform.
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dynamic embrittlement in an age hardenable copper chromium Alloy
Scripta Materialia, 1996Co-Authors: R D K Misra, V Satya V PrasadAbstract:Copper containing up to {approximately}1 weight % chromium is a Precipitation Hardening Alloy exhibiting good room temperature strength, ductility and high electrical and thermal conductivity. Age-hardenable Cu-Cr Alloys have been found to suffer from embrittlement in the temperature range 400--800 K. Grain boundary segregation of sulfur has been suggested to be the cause. Minor additions of Zr and Ti have been found to significantly improve the hot ductility of these Alloys and this has been attributed to scavenging of grain boundary sulfur as zirconium sulfide. The mechanism of embrittlement during hot deformation processing of Cu-Cr Alloy and other copper-based Alloys is far from understood and efforts are continuing to understand the embrittlement process in these Alloys.
R D K Misra - One of the best experts on this subject based on the ideXlab platform.
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dynamic embrittlement in an age hardenable copper chromium Alloy
Scripta Materialia, 1996Co-Authors: R D K Misra, V Satya V PrasadAbstract:Copper containing up to {approximately}1 weight % chromium is a Precipitation Hardening Alloy exhibiting good room temperature strength, ductility and high electrical and thermal conductivity. Age-hardenable Cu-Cr Alloys have been found to suffer from embrittlement in the temperature range 400--800 K. Grain boundary segregation of sulfur has been suggested to be the cause. Minor additions of Zr and Ti have been found to significantly improve the hot ductility of these Alloys and this has been attributed to scavenging of grain boundary sulfur as zirconium sulfide. The mechanism of embrittlement during hot deformation processing of Cu-Cr Alloy and other copper-based Alloys is far from understood and efforts are continuing to understand the embrittlement process in these Alloys.
Sh Zangeneh - One of the best experts on this subject based on the ideXlab platform.
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determination of johnson cook plasticity model parameters for inconel718
Journal of Materials Engineering and Performance, 2017Co-Authors: H K Farahani, Mostafa Ketabchi, Sh ZangenehAbstract:In order to simulate foreign object damage (FOD) phenomenon in aircraft high-pressure compressor blades made of a nickel-based super-Alloy, Johnson–Cook (J–C) plasticity model was used. For prediction of material’s plastic behavior at temperature of 400 °C (working temperature of the blades) in the range of strain rates associated with the FOD phenomenon (in order of 106 s−1), material parameters of A, B, C, n and m for the J–C plasticity model had to be determined experimentally. Parameters of A, B and n with values of 1108, 699 MPa and 0.5189, respectively, were obtained from quasi-static tensile tests. Moreover, m was determined to be 1.2861, also through quasi-static tensile tests with a strain rate of 1 s−1 at three temperatures of 475, 550 and 625 °C. However, in order to determine C, firstly a steel ball was impacted on the surface of a flat specimen made of a Precipitation-Hardening Alloy, and then, the impact site was 3D scanned to obtain the induced crater profile. Finally, the impact test (ballistic) was simulated using Abaqus, and a C value of 0.0085 was determined by comparing the actual crater profile with the one obtained from the simulation through a trial-and-error approach.
Salvan Claudia - One of the best experts on this subject based on the ideXlab platform.
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Alliage de cuivre à durcissement structural mis en œuvre par fusion laser sur lit de poudre : lien entre microstructure et propriétés mécaniques, thermiques et électriques
HAL CCSD, 2021Co-Authors: Salvan ClaudiaAbstract:The CuCrZr is a Precipitation Hardening Alloy, used for its good electrical and thermal properties combined to high mechanical properties. Using additive manufacturing technologies, and more precisely the laser powder bed fusion (L-PBF) process, offers the possibility to build highly complex parts for the conception of compact and efficient heat exchangers. However, the high optical reflectivity of the Alloy at the standard laser wavelength added to the high thermal conductivity of the Alloy require the use of a high energy density during the fabrication. Regarding the environmental cost and the risk of machine damage, this is not always a desirable choice.The research aimed to (i) reduce the optical reflectivity of the powder by a controlled particle oxidation, (ii) optimize the process parameters in order to build dense part using the different powers available on two machines, (iii) compare the L-PBF CuCrZr microstructure, before and after heat treatment to wrought and HIP (hot isostatic pressing) CuCrZr and (iv) explain the L-PBF CuCrZr mechanical behavior relying on SEM-EBSD and TEM microstructural characterization through the discussion of the different Hardening mechanisms via a mechanical model.This work shows the link between the chemical composition and the thickness of the oxide layer on particles, and the powder optical reflectivity and flow properties. This thesis presents L-PBF CuCrZr microstructural, mechanical (hardness and traction at 20°C and 250°C), electrical and thermal properties before and after two heat treatments (the first one is composed of a solution annealing, a water quench and an age Hardening steps and the second one is only composed of a direct age Hardening), compared with CuCrZr references properties. We have shown that a direct age Hardening on L-PBF materials provides high mechanical properties (184 HV1 hardness, Rp0.2=527 MPa, Rm=585MPa) while keeping a good elongation (14%), electrical (42 MS.m-1) and thermal properties (375 W.m-1.K-1 at 100°C). Those results are explained by (i) the presence, in the as built L-PBF part, of a supersaturated solid solution with all the Cr dissolved, allowing, after direct age Hardening to have a high nano-precipitates density, and thus a high Precipitation Hardening, (ii) the presence of a high dislocations density linked to the characteristical presence of solidification cells in the as built state, and widely preserved thanks to the direct age Hardening heat treatment.Le CuCrZr est un alliage à durcissement structural utilisé pour ses bonnes propriétés électriques et thermiques combinées à des propriétés mécaniques élevées. La fabrication additive, via le procédé de fusion laser sur lit de poudre (ou FLLP), offre de son côté la possibilité de construire des pièces particulièrement complexes et permettrait par exemple, la réalisation d’échangeurs de chaleur plus compacts et plus efficaces. Cependant, la forte réflectivité optique de l’alliage à la longueur d’onde des lasers standards et sa forte conductivité thermique nécessitent l’utilisation de densités d’énergie très élevées, ce qui n’est pas toujours possible ni même souhaitable au regard du coût environnemental et du risque d’endommagement des machines que cela entraine.Les travaux de cette thèse visent à (i) réduire la réflectivité de la poudre par oxydation contrôlée des particules, (ii) optimiser les paramètres procédés afin d'obtenir des pièces denses sur 2 technologies de machine de puissances laser différentes (iii) comparer les microstructures des CuCrZr FLLP avant/après traitement thermique avec celles de deux références, CuCrZr forgé et CuCrZr obtenu par Compaction Isostatique à Chaud (CIC) et (iv) expliquer l’origine des propriétés mécaniques des CuCrZr FLLP en s’appuyant sur des analyses microstructurales MEB-EBSD et MET tout en discutant les contributions respectives des différents mécanismes de durcissement mis en jeu à l'aide d'un modèle mécanique.Nos travaux montrent les liens entre la nature et l’épaisseur de la couche d’oxyde en surface des particules et les propriétés de réflectivité optique et d’écoulement de la poudre. Cette thèse présente les propriétés microstructurales, mécaniques (dureté et traction à 20°C et 250°C), électriques et thermiques de CuCrZr FLLP avant et après deux traitements thermiques (un traitement composé d’une mise en solution, d’une trempe et d’un revenu, et un autre composé d’un simple revenu), et les compare à celles des CuCrZr de référence. Nous avons aussi montré qu’un simple revenu appliqué aux pièces FLLP permet d’obtenir des propriétés mécaniques très élevées (dureté de 184 HV1, Rp0,2 de 527 MPa, Rm de 585 MPa) tout en conservant un allongement non négligeable (14%) et de bonnes propriétés électrique (42 MS.m-1) et thermique (375 W.m-1.K-1 à 100°C). Elles s’expliquent principalement par : (i) la présence, dans le matériau brut FLLP, d'une solution solide sursaturée dans laquelle la totalité du Cr est dissoute permettant, après revenu, d'obtenir une très forte densité de nano-précipités, et donc un fort durcissement structural, (ii) la présence d’une forte densité de dislocations associées aux cellules de solidification, caractéristiques de l’état brut de FLLP, mais largement préservées par le simple revenu
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Manufacturing of a Precipitation hardened copper Alloy by laser powder bed fusion : from microstructure to mechanical, thermal and electrical properties
2021Co-Authors: Salvan ClaudiaAbstract:Le CuCrZr est un alliage à durcissement structural utilisé pour ses bonnes propriétés électriques et thermiques combinées à des propriétés mécaniques élevées. La fabrication additive, via le procédé de fusion laser sur lit de poudre (ou FLLP), offre de son côté la possibilité de construire des pièces particulièrement complexes et permettrait par exemple, la réalisation d’échangeurs de chaleur plus compacts et plus efficaces. Cependant, la forte réflectivité optique de l’alliage à la longueur d’onde des lasers standards et sa forte conductivité thermique nécessitent l’utilisation de densités d’énergie très élevées, ce qui n’est pas toujours possible ni même souhaitable au regard du coût environnemental et du risque d’endommagement des machines que cela entraine.Les travaux de cette thèse visent à (i) réduire la réflectivité de la poudre par oxydation contrôlée des particules, (ii) optimiser les paramètres procédés afin d'obtenir des pièces denses sur 2 technologies de machine de puissances laser différentes (iii) comparer les microstructures des CuCrZr FLLP avant/après traitement thermique avec celles de deux références, CuCrZr forgé et CuCrZr obtenu par Compaction Isostatique à Chaud (CIC) et (iv) expliquer l’origine des propriétés mécaniques des CuCrZr FLLP en s’appuyant sur des analyses microstructurales MEB-EBSD et MET tout en discutant les contributions respectives des différents mécanismes de durcissement mis en jeu à l'aide d'un modèle mécanique.Nos travaux montrent les liens entre la nature et l’épaisseur de la couche d’oxyde en surface des particules et les propriétés de réflectivité optique et d’écoulement de la poudre. Cette thèse présente les propriétés microstructurales, mécaniques (dureté et traction à 20°C et 250°C), électriques et thermiques de CuCrZr FLLP avant et après deux traitements thermiques (un traitement composé d’une mise en solution, d’une trempe et d’un revenu, et un autre composé d’un simple revenu), et les compare à celles des CuCrZr de référence. Nous avons aussi montré qu’un simple revenu appliqué aux pièces FLLP permet d’obtenir des propriétés mécaniques très élevées (dureté de 184 HV1, Rp0,2 de 527 MPa, Rm de 585 MPa) tout en conservant un allongement non négligeable (14%) et de bonnes propriétés électrique (42 MS.m-1) et thermique (375 W.m-1.K-1 à 100°C). Elles s’expliquent principalement par : (i) la présence, dans le matériau brut FLLP, d'une solution solide sursaturée dans laquelle la totalité du Cr est dissoute permettant, après revenu, d'obtenir une très forte densité de nano-précipités, et donc un fort durcissement structural, (ii) la présence d’une forte densité de dislocations associées aux cellules de solidification, caractéristiques de l’état brut de FLLP, mais largement préservées par le simple revenu.The CuCrZr is a Precipitation Hardening Alloy, used for its good electrical and thermal properties combined to high mechanical properties. Using additive manufacturing technologies, and more precisely the laser powder bed fusion (L-PBF) process, offers the possibility to build highly complex parts for the conception of compact and efficient heat exchangers. However, the high optical reflectivity of the Alloy at the standard laser wavelength added to the high thermal conductivity of the Alloy require the use of a high energy density during the fabrication. Regarding the environmental cost and the risk of machine damage, this is not always a desirable choice.The research aimed to (i) reduce the optical reflectivity of the powder by a controlled particle oxidation, (ii) optimize the process parameters in order to build dense part using the different powers available on two machines, (iii) compare the L-PBF CuCrZr microstructure, before and after heat treatment to wrought and HIP (hot isostatic pressing) CuCrZr and (iv) explain the L-PBF CuCrZr mechanical behavior relying on SEM-EBSD and TEM microstructural characterization through the discussion of the different Hardening mechanisms via a mechanical model.This work shows the link between the chemical composition and the thickness of the oxide layer on particles, and the powder optical reflectivity and flow properties. This thesis presents L-PBF CuCrZr microstructural, mechanical (hardness and traction at 20°C and 250°C), electrical and thermal properties before and after two heat treatments (the first one is composed of a solution annealing, a water quench and an age Hardening steps and the second one is only composed of a direct age Hardening), compared with CuCrZr references properties. We have shown that a direct age Hardening on L-PBF materials provides high mechanical properties (184 HV1 hardness, Rp0.2=527 MPa, Rm=585MPa) while keeping a good elongation (14%), electrical (42 MS.m-1) and thermal properties (375 W.m-1.K-1 at 100°C). Those results are explained by (i) the presence, in the as built L-PBF part, of a supersaturated solid solution with all the Cr dissolved, allowing, after direct age Hardening to have a high nano-precipitates density, and thus a high Precipitation Hardening, (ii) the presence of a high dislocations density linked to the characteristical presence of solidification cells in the as built state, and widely preserved thanks to the direct age Hardening heat treatment
H K Farahani - One of the best experts on this subject based on the ideXlab platform.
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determination of johnson cook plasticity model parameters for inconel718
Journal of Materials Engineering and Performance, 2017Co-Authors: H K Farahani, Mostafa Ketabchi, Sh ZangenehAbstract:In order to simulate foreign object damage (FOD) phenomenon in aircraft high-pressure compressor blades made of a nickel-based super-Alloy, Johnson–Cook (J–C) plasticity model was used. For prediction of material’s plastic behavior at temperature of 400 °C (working temperature of the blades) in the range of strain rates associated with the FOD phenomenon (in order of 106 s−1), material parameters of A, B, C, n and m for the J–C plasticity model had to be determined experimentally. Parameters of A, B and n with values of 1108, 699 MPa and 0.5189, respectively, were obtained from quasi-static tensile tests. Moreover, m was determined to be 1.2861, also through quasi-static tensile tests with a strain rate of 1 s−1 at three temperatures of 475, 550 and 625 °C. However, in order to determine C, firstly a steel ball was impacted on the surface of a flat specimen made of a Precipitation-Hardening Alloy, and then, the impact site was 3D scanned to obtain the induced crater profile. Finally, the impact test (ballistic) was simulated using Abaqus, and a C value of 0.0085 was determined by comparing the actual crater profile with the one obtained from the simulation through a trial-and-error approach.