C. Lin, Ching-Pao Wang, S. Shieh, Yao-Jen Chang, Tony Huang, Dongzhou Zhang, Chin-wei Wang, J. Yeh, An-Chou Yeh, J. Juang
The pressure-induced phase transitions in CoCrFeNi and CoCrFeMnNi high entropy alloys (HEAs) at ambient temperature at pressure up to 24.0(2) and 19.4(2) GPa, respectively, were investigated using angle-dispersive X-ray diffraction (ADXRD). Structurally at ambient pressure, both CoCrFeNi and CoCrFeMnNi HEAs consist of face-centered cubic (fcc) structure with different lattice constants which are arisen primarily from the cellular growth of alloy during solidification. Insitu ADXRD measurements revealed no evidence of structural transformation in CoCrFeNi HEAs up to 24.0(2) GPa. The intrinsic stacking fault (ISF) begins to appear at 1.7(1) GPa and sustains up to 19.4(2) GPa. Moreover, an fcc to hexagonal close-packed (hcp) structural phase transition emerges at around 7.0(1) GPa in CoCrFeMnNi HEAs. The pressure dependent lattice constants and volume compression yield the zero-pressure isothermal bulk moduli of 187(4) GPa while the normalized c/a ratio 1.636(1) for the resultant hcp phase. The quantitative correlation of the ISF diffraction intensity shows that the appearance of ISF disrupts the crystal lattice to trigger, at around 7.0(1) GPa, fcc-to-hcp phase transition which persists sluggishly to the highest experiment pressure. Neutron powder diffraction (NPD) at pressure up to 8.9(2) GPa was performed in CoCrFeMnNi HEAs at ambient temperature to clarify the significance of pressure induced suppression of local magnetic moment on destabilization of the initial fcc structure. The results, however, suggest that the magnetism may only play a minor role, if not none, in facilitating the pressure-induced fcc-to-hcp phase transition in CoCrFeMnNi HEAs.
{"title":"The Role of Intrinsic Stacking Fault in Facilitating the Pressure-Induced Phase Transition in CoCrFeMnNi High Entropy Alloys","authors":"C. Lin, Ching-Pao Wang, S. Shieh, Yao-Jen Chang, Tony Huang, Dongzhou Zhang, Chin-wei Wang, J. Yeh, An-Chou Yeh, J. Juang","doi":"10.2139/ssrn.3711254","DOIUrl":"https://doi.org/10.2139/ssrn.3711254","url":null,"abstract":"The pressure-induced phase transitions in CoCrFeNi and CoCrFeMnNi high entropy alloys (HEAs) at ambient temperature at pressure up to 24.0(2) and 19.4(2) GPa, respectively, were investigated using angle-dispersive X-ray diffraction (ADXRD). Structurally at ambient pressure, both CoCrFeNi and CoCrFeMnNi HEAs consist of face-centered cubic (<i>fcc</i>) structure with different lattice constants which are arisen primarily from the cellular growth of alloy during solidification. <i>Insitu</i> ADXRD measurements revealed no evidence of structural transformation in CoCrFeNi HEAs up to 24.0(2) GPa. The intrinsic stacking fault (ISF) begins to appear at 1.7(1) GPa and sustains up to 19.4(2) GPa. Moreover, an <i>fcc</i> to hexagonal close-packed (<i>hcp</i>) structural phase transition emerges at around 7.0(1) GPa in CoCrFeMnNi HEAs. The pressure dependent lattice constants and volume compression yield the zero-pressure isothermal bulk moduli of 187(4) GPa while the normalized <i>c/a</i> ratio 1.636(1) for the resultant <i>hcp</i> phase. The quantitative correlation of the ISF diffraction intensity shows that the appearance of ISF disrupts the crystal lattice to trigger, at around 7.0(1) GPa, <i>fcc-to-hcp</i> phase transition which persists sluggishly to the highest experiment pressure. Neutron powder diffraction (NPD) at pressure up to 8.9(2) GPa was performed in CoCrFeMnNi HEAs at ambient temperature to clarify the significance of pressure induced suppression of local magnetic moment on destabilization of the initial <i>fcc</i> structure. The results, however, suggest that the magnetism may only play a minor role, if not none, in facilitating the pressure-induced <i>fcc-to-hcp</i> phase transition in CoCrFeMnNi HEAs.","PeriodicalId":18731,"journal":{"name":"Materials Processing & Manufacturing eJournal","volume":"43 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79303770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract Cracking and delamination in constrained films and coatings during fabrication and service has been an important subject of scientific inquiry for several decades. Considerable past efforts have focused on developing analytical models based predicting steady state energy release rates to determine the occurrence of either cracking and/or delamination in thin films. Such models have been reconciled into a ‘Design Map’. However, the extent of available experimental validation of such Design Maps is limited. In addition, these analytical Design Maps lack the description of nuances in the processing of layered films such as progressive incremental deposition. In this study, the interplay between cracking and delamination in progressively deposited plasma sprayed coatings is defined based on the aforementioned models. Following the adaptation of the models and presiding assumptions, a carefully designed set of experiments to probe responses from different ceramics and process conditions have been conducted, which allowed the controlled observation of cracking and/or delamination events. These experiments elucidated the underlying conditions that determine the onset of such stress relaxation events. The experimental data is reconciled with an adapted analytical Design Map for single, isolated, rapidly solidified droplets (splats) and for incrementally deposited thick plasma sprayed coatings, thus providing a framework for the robust design and processing of advanced coatings.
{"title":"Interplay between Cracking and Delamination in Incrementally Deposited Plasma Sprayed Coatings","authors":"S. Shinde, S. Sampath","doi":"10.2139/ssrn.3797425","DOIUrl":"https://doi.org/10.2139/ssrn.3797425","url":null,"abstract":"Abstract Cracking and delamination in constrained films and coatings during fabrication and service has been an important subject of scientific inquiry for several decades. Considerable past efforts have focused on developing analytical models based predicting steady state energy release rates to determine the occurrence of either cracking and/or delamination in thin films. Such models have been reconciled into a ‘Design Map’. However, the extent of available experimental validation of such Design Maps is limited. In addition, these analytical Design Maps lack the description of nuances in the processing of layered films such as progressive incremental deposition. In this study, the interplay between cracking and delamination in progressively deposited plasma sprayed coatings is defined based on the aforementioned models. Following the adaptation of the models and presiding assumptions, a carefully designed set of experiments to probe responses from different ceramics and process conditions have been conducted, which allowed the controlled observation of cracking and/or delamination events. These experiments elucidated the underlying conditions that determine the onset of such stress relaxation events. The experimental data is reconciled with an adapted analytical Design Map for single, isolated, rapidly solidified droplets (splats) and for incrementally deposited thick plasma sprayed coatings, thus providing a framework for the robust design and processing of advanced coatings.","PeriodicalId":18731,"journal":{"name":"Materials Processing & Manufacturing eJournal","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75264296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Astrid Weyand, S. Schmitt, L. Petruschke, G. Elserafi, M. Weigold
Due to the constant changes in the production environment and the increasing relevance of sustainability and digitalisation in the industrial sector, there is a corresponding need for constant development of learning factories and the offered range of courses. To achieve this, not only learning content but also the technical infrastructure for knowledge transfer must be expanded in learning factories. Approaches that exist so far focus on the development of new learning factories to implement new or existing topics, although the already existing learning factories could be expanded and changed to these varied needs. Since a systematic approach is lacking so far, the competency-based design for the development of learning factories was used as a basis, developed further with focus on the technical infrastructure expansion. Subsequently, this approach is applied to the ETA Learning Factory at Technical University of Darmstadt. The ETA use case focuses on the topic of product-specific carbon footprint calculation. Therefore, technical infrastructure such as traceability systems, dashboards for visualisation or newly implemented efficiency measures on machine tools is added. The approach can be applied to a variety of topics.
{"title":"Approach for Implementing New Topics in Learning Factories – Application of Product-specific Carbon Footprint Analysis","authors":"Astrid Weyand, S. Schmitt, L. Petruschke, G. Elserafi, M. Weigold","doi":"10.2139/ssrn.3863447","DOIUrl":"https://doi.org/10.2139/ssrn.3863447","url":null,"abstract":"Due to the constant changes in the production environment and the increasing relevance of sustainability and digitalisation in the industrial sector, there is a corresponding need for constant development of learning factories and the offered range of courses. To achieve this, not only learning content but also the technical infrastructure for knowledge transfer must be expanded in learning factories. Approaches that exist so far focus on the development of new learning factories to implement new or existing topics, although the already existing learning factories could be expanded and changed to these varied needs. Since a systematic approach is lacking so far, the competency-based design for the development of learning factories was used as a basis, developed further with focus on the technical infrastructure expansion. Subsequently, this approach is applied to the ETA Learning Factory at Technical University of Darmstadt. The ETA use case focuses on the topic of product-specific carbon footprint calculation. Therefore, technical infrastructure such as traceability systems, dashboards for visualisation or newly implemented efficiency measures on machine tools is added. The approach can be applied to a variety of topics.","PeriodicalId":18731,"journal":{"name":"Materials Processing & Manufacturing eJournal","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89470487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Blattner, J. Wolfartsberger, René Lindorfer, R. Froschauer, Sebastian Pimminger, W. Kurschl
Various assistive systems for supporting manual assembly tasks in industry have been proposed within the last years. These systems range from simple work instructions on screens, to animated mixed reality and in-situ projected hints directly onto the work-piece. Several design approaches exist for these systems. Commonly, assistive systems are tested and evaluated using abstract use cases with widely available building blocks (e.g. Duplo or Lego). These approaches work to test simple picking and placing tasks, but cannot reproduce the complexity of real assembly, which may include the tightening of screws, adding components from specific directions or attaching cables in a predefined way. Other evaluation approaches make use of realistic work processes from real industrial contexts. However, these evaluations are less controllable and hardly replicable. Our work presents a realistic and easyto-recreate approach to evaluate assistive systems for manual assembly tasks. It comprises a 3D-modelled object that considers several procedures and aspects of manual assembly and, as an abstract assembly object, helps to improve the usability of laboratory developed assistive systems. The model itself is developed to be 3D printed and uses standardized components to make it easily available for research and learning factories around the globe. With this approach, we want to support researchers in comparing and evaluating assistive systems for industrial assembly tasks by providing a realistic and easy-to-use test setup with high internal and external validity.
{"title":"A Standardized Approach to Evaluate Assistive Systems for Manual Assembly Tasks in Industry","authors":"J. Blattner, J. Wolfartsberger, René Lindorfer, R. Froschauer, Sebastian Pimminger, W. Kurschl","doi":"10.2139/ssrn.3858632","DOIUrl":"https://doi.org/10.2139/ssrn.3858632","url":null,"abstract":"Various assistive systems for supporting manual assembly tasks in industry have been proposed within the last years. These systems range from simple work instructions on screens, to animated mixed reality and in-situ projected hints directly onto the work-piece. Several design approaches exist for these systems. Commonly, assistive systems are tested and evaluated using abstract use cases with widely available building blocks (e.g. Duplo or Lego). These approaches work to test simple picking and placing tasks, but cannot reproduce the complexity of real assembly, which may include the tightening of screws, adding components from specific directions or attaching cables in a predefined way. Other evaluation approaches make use of realistic work processes from real industrial contexts. However, these evaluations are less controllable and hardly replicable. Our work presents a realistic and easyto-recreate approach to evaluate assistive systems for manual assembly tasks. It comprises a 3D-modelled object that considers several procedures and aspects of manual assembly and, as an abstract assembly object, helps to improve the usability of laboratory developed assistive systems. The model itself is developed to be 3D printed and uses standardized components to make it easily available for research and learning factories around the globe. With this approach, we want to support researchers in comparing and evaluating assistive systems for industrial assembly tasks by providing a realistic and easy-to-use test setup with high internal and external validity.","PeriodicalId":18731,"journal":{"name":"Materials Processing & Manufacturing eJournal","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89986175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Kenney, Katie O’Donnell, M. Quintana, P. Collins
Abstract Detailed analysis of defects such as spherical porosity can act as informants, providing some information regarding the complex and often hidden physics associated with additive manufacturing. Variation in the presence and nature of these defects can shed new insights into the AM process. In this paper, the compositional, crystallographic, microstructural, and morphological characteristics surrounding gas pores in Electron Beam Melted Ti-6Al-4V have been assessed and correlated with different scanning strategies (raster and two point melting ones, Dehoff and random). The large spherical pores (>25μm), exclusively present in raster scan, exhibit perturbations normal to the vertical sidewalls of the pores that are likely the result of elastic instabilities resulting from chemical and crystallographic variations and initiated by vertical compression caused by thermal stresses related to the cyclic process – effectively a form of microbuckling. Electron backscatter diffraction maps support the theory that these perturbations occur at elevated temperatures and prior to the final solid-solid phase transformation.
{"title":"Spherical Pores as ‘Microstructural Informants’: Understanding Compositional, Thermal, and Mechanical Gyrations in Additively Manufactured Ti-6Al-4V","authors":"M. Kenney, Katie O’Donnell, M. Quintana, P. Collins","doi":"10.2139/ssrn.3714497","DOIUrl":"https://doi.org/10.2139/ssrn.3714497","url":null,"abstract":"Abstract Detailed analysis of defects such as spherical porosity can act as informants, providing some information regarding the complex and often hidden physics associated with additive manufacturing. Variation in the presence and nature of these defects can shed new insights into the AM process. In this paper, the compositional, crystallographic, microstructural, and morphological characteristics surrounding gas pores in Electron Beam Melted Ti-6Al-4V have been assessed and correlated with different scanning strategies (raster and two point melting ones, Dehoff and random). The large spherical pores (>25μm), exclusively present in raster scan, exhibit perturbations normal to the vertical sidewalls of the pores that are likely the result of elastic instabilities resulting from chemical and crystallographic variations and initiated by vertical compression caused by thermal stresses related to the cyclic process – effectively a form of microbuckling. Electron backscatter diffraction maps support the theory that these perturbations occur at elevated temperatures and prior to the final solid-solid phase transformation.","PeriodicalId":18731,"journal":{"name":"Materials Processing & Manufacturing eJournal","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85397033","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The generation of spatters during laser powder bed fusion (L-PBF) of Alloy 718 is known to be detrimental for the re-use of the feedstock powder and the quality of the final product. In this study, dedicated powder sampling from different positions within the build chamber and powder bed was performed. The results clearly indicate the importance of the surface-to-volume ratio of the built components on powder degradation, as demonstrated by the analysis of the powder using capsules filled with dense lattice structures. Extensive formation of Al- and Cr-rich oxides on the entrained powder deposited on the gas inlet and outlet was detected. Significant oxygen pick-up by spatter particles compared to the virgin powder was measured (>300 ppm O2); while the as-built material experienced a slight loss (~30 ppm O2). The change in the microstructure of spatter particles in comparison to the virgin powder, namely the primary dendrite arm spacing, indicates significantly higher cooling rate during spatter solidification, estimated to be of about 108 K/s, compared to around 106 K/s for the virgin powder and 107 K/s for the L-PBF component. These findings allows to evaluate the extent of powder degradation during L-PBF and establish the oxygen balance of the process.
{"title":"Oxygen Balance During Laser Powder Bed Fusion of Alloy 718","authors":"C. Pauzon, A. Raza, Eduard Hryha, P. Forêt","doi":"10.2139/ssrn.3805236","DOIUrl":"https://doi.org/10.2139/ssrn.3805236","url":null,"abstract":"Abstract The generation of spatters during laser powder bed fusion (L-PBF) of Alloy 718 is known to be detrimental for the re-use of the feedstock powder and the quality of the final product. In this study, dedicated powder sampling from different positions within the build chamber and powder bed was performed. The results clearly indicate the importance of the surface-to-volume ratio of the built components on powder degradation, as demonstrated by the analysis of the powder using capsules filled with dense lattice structures. Extensive formation of Al- and Cr-rich oxides on the entrained powder deposited on the gas inlet and outlet was detected. Significant oxygen pick-up by spatter particles compared to the virgin powder was measured (>300 ppm O2); while the as-built material experienced a slight loss (~30 ppm O2). The change in the microstructure of spatter particles in comparison to the virgin powder, namely the primary dendrite arm spacing, indicates significantly higher cooling rate during spatter solidification, estimated to be of about 108 K/s, compared to around 106 K/s for the virgin powder and 107 K/s for the L-PBF component. These findings allows to evaluate the extent of powder degradation during L-PBF and establish the oxygen balance of the process.","PeriodicalId":18731,"journal":{"name":"Materials Processing & Manufacturing eJournal","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73369502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shao-Wen Young, Mitsutaka Sato, Kazuhiro Yamamitsu, Y. Shimada, Yongjie Zhang, G. Miyamoto, T. Furuhara
Abstract The precipitation behaviors of alloy nitrides during the high-temperature tempering of Fe-0.3mass%N-1mass%M (M: Cr, Mo, Mn, or Si) martensite obtained by gaseous nitriding and quenching was investigated. Resistance to temper softening was observed with the addition of Mn, Cr, and Mo and secondary hardening occurred in the Cr and Mo alloys at tempering temperature above 673K although Si addition did not result in clear change in temper softening in comparison to the Fe-N binary case. X-ray diffraction analysis and conventional TEM observation shows the precipitation of iron nitride (γ'-Fe4N) and alloy nitride during tempering at 773K. Cs-corrected STEM-HAADF observation revealed that metastable mono-layered nitrogen-alloying element clusters are formed along {001}α' plane and they are eventually thickened into B1-type MN precipitate in the Cr and Mo alloys. In the Mn alloy, B1-type Mn nitride was detected which presumably changes to η-Mn3N2 by thickening. 3DAP analysis confirmed the ratio of nitrogen and alloying element of the nitride corresponds to the structure deduced by STEM-HAADF. Clustering analysis of 'matrix' indicated that there are still finer clusters which could not be clearly visualized in STEM-HAADF and 3DAP. Hardness after tempering was examined by strengthening by precipitation and dislocations, suggesting that undetected Cr-N clusters should contribute to hardening in the Cr alloy.
{"title":"Effect of Alloying Elements on the High-Temperature Tempering of Fe-0.3N Martensite","authors":"Shao-Wen Young, Mitsutaka Sato, Kazuhiro Yamamitsu, Y. Shimada, Yongjie Zhang, G. Miyamoto, T. Furuhara","doi":"10.2139/ssrn.3661907","DOIUrl":"https://doi.org/10.2139/ssrn.3661907","url":null,"abstract":"Abstract The precipitation behaviors of alloy nitrides during the high-temperature tempering of Fe-0.3mass%N-1mass%M (M: Cr, Mo, Mn, or Si) martensite obtained by gaseous nitriding and quenching was investigated. Resistance to temper softening was observed with the addition of Mn, Cr, and Mo and secondary hardening occurred in the Cr and Mo alloys at tempering temperature above 673K although Si addition did not result in clear change in temper softening in comparison to the Fe-N binary case. X-ray diffraction analysis and conventional TEM observation shows the precipitation of iron nitride (γ'-Fe4N) and alloy nitride during tempering at 773K. Cs-corrected STEM-HAADF observation revealed that metastable mono-layered nitrogen-alloying element clusters are formed along {001}α' plane and they are eventually thickened into B1-type MN precipitate in the Cr and Mo alloys. In the Mn alloy, B1-type Mn nitride was detected which presumably changes to η-Mn3N2 by thickening. 3DAP analysis confirmed the ratio of nitrogen and alloying element of the nitride corresponds to the structure deduced by STEM-HAADF. Clustering analysis of 'matrix' indicated that there are still finer clusters which could not be clearly visualized in STEM-HAADF and 3DAP. Hardness after tempering was examined by strengthening by precipitation and dislocations, suggesting that undetected Cr-N clusters should contribute to hardening in the Cr alloy.","PeriodicalId":18731,"journal":{"name":"Materials Processing & Manufacturing eJournal","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73010448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Maistro, C. Oikonomou, S. Hosseini, S.R. Brorson
A maraging grade and a modified H13 type tool steel were used as testing materials to study the possibility of healing printing defects while combining a solutionizing/hardening treatment to the components. Extensive mechanical testing and microstructural analysis showed that the high-pressure heat treatment can stabilize retained austenite in maraging grades, but has no effects on the aging kinetics. A HIP temperature of 850°C is not sufficient to heal printing defects in highly defective maraging components, while 1020°C were sufficient to fully heal a modified H13 component. Increasing HIP temperature over 1140°C causes lower impact toughness, due to grain growth and/or precipitation and growth of MnS.
{"title":"Quenching and Hot Isostatic Pressing of Additively Manufactured Tool Steel","authors":"G. Maistro, C. Oikonomou, S. Hosseini, S.R. Brorson","doi":"10.2139/ssrn.3785874","DOIUrl":"https://doi.org/10.2139/ssrn.3785874","url":null,"abstract":"A maraging grade and a modified H13 type tool steel were used as testing materials to study the possibility of healing printing defects while combining a solutionizing/hardening treatment to the components. Extensive mechanical testing and microstructural analysis showed that the high-pressure heat treatment can stabilize retained austenite in maraging grades, but has no effects on the aging kinetics. A HIP temperature of 850°C is not sufficient to heal printing defects in highly defective maraging components, while 1020°C were sufficient to fully heal a modified H13 component. Increasing HIP temperature over 1140°C causes lower impact toughness, due to grain growth and/or precipitation and growth of MnS.","PeriodicalId":18731,"journal":{"name":"Materials Processing & Manufacturing eJournal","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86976515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Silvia Lasala, R. Privat, O. Herbinet, Philippe Arpentinier, D. Bonalumi, J. Jaubert
Abstract Thermal engines, particularly closed power cycles, are currently a focus of many studies mainly because they represent the only way to exploit renewable thermal energy. To increase the exploitation of available thermal sources, this work investigates the higher potential offered by a complementary technology based on the use of reactive working fluids instead of inert fluids: the here-called “thermo-chemical” engine. Such a power cycle enables the simultaneous conversion of thermal and chemical energy into work. Based on a theoretical approach, this paper explores engine performance considering different stoichiometries and thermodynamic characteristics of reactive fluids and different operating conditions. It is shown that the use of specific equilibrated reactions occurring in the gaseous phase might lead to extremely powerful and highly efficient energy conversion systems in the whole current domain of the application of power cycles. Moreover, it is demonstrated that, unlike classical thermal machines, a thermo-chemical engine allows efficient and powerful exploitation of low-temperature heat sources and high-temperature cold sinks, which in general, characterize renewable thermal energy.
{"title":"Thermo-Chemical Engines: Unexploited High-Potential Energy Converters","authors":"Silvia Lasala, R. Privat, O. Herbinet, Philippe Arpentinier, D. Bonalumi, J. Jaubert","doi":"10.2139/ssrn.3677472","DOIUrl":"https://doi.org/10.2139/ssrn.3677472","url":null,"abstract":"Abstract Thermal engines, particularly closed power cycles, are currently a focus of many studies mainly because they represent the only way to exploit renewable thermal energy. To increase the exploitation of available thermal sources, this work investigates the higher potential offered by a complementary technology based on the use of reactive working fluids instead of inert fluids: the here-called “thermo-chemical” engine. Such a power cycle enables the simultaneous conversion of thermal and chemical energy into work. Based on a theoretical approach, this paper explores engine performance considering different stoichiometries and thermodynamic characteristics of reactive fluids and different operating conditions. It is shown that the use of specific equilibrated reactions occurring in the gaseous phase might lead to extremely powerful and highly efficient energy conversion systems in the whole current domain of the application of power cycles. Moreover, it is demonstrated that, unlike classical thermal machines, a thermo-chemical engine allows efficient and powerful exploitation of low-temperature heat sources and high-temperature cold sinks, which in general, characterize renewable thermal energy.","PeriodicalId":18731,"journal":{"name":"Materials Processing & Manufacturing eJournal","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83650437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The hybrid structure composed of aluminum alloy and carbon fiber reinforced plastics could combine their advantages. In order to investigate the weldability of these two lightweight materials, the hybrid joints of 5052 aluminum alloy (AA5052) and carbon fiber reinforced polyether ether ketone composites (CF-PEEK) were fabricated by friction stir spot welding. The variance analysis revealed that the dwell time and plunge speed were the most significant factors. By optimizing the welding parameters, the ultimate tensile shear load reached 2690±64 N (the dwell time: 8 s, the plunge speed: 10 mm/min). The interface could be divided into pin-affected zone, shoulder-affected zone, resin adhesive zone and resin concentrated zone. Since resin concentrated zone could not provide interfacial bonding due to delamination, the shoulder-affected zone and pin-affected zone were decisive regions for mechanical properties. The bonding mechanism included three parts: adhesive bonding provided by re-solidified resin, macro-mechanical interlocking of aluminum alloy that entered CF-PEEK, and micro-mechanical interlocking of resin that was tightly trapped at surface slits as well as the carbon fibers beset into AA5052. This work clarifies the interfacial characteristics of AA5052/CF-PEEK hybrid joints and provides an approach to improve the mechanical properties.
{"title":"Friction Stir Spot Welding of 5052 Aluminum Alloy to Carbon Fiber Reinforced Polyether Ether Ketone Composites","authors":"Honggang Dong, Zuyang Tang, Peng Li, Baosheng Wu, X. Hao, Chaoqun Ma","doi":"10.2139/ssrn.3805251","DOIUrl":"https://doi.org/10.2139/ssrn.3805251","url":null,"abstract":"Abstract The hybrid structure composed of aluminum alloy and carbon fiber reinforced plastics could combine their advantages. In order to investigate the weldability of these two lightweight materials, the hybrid joints of 5052 aluminum alloy (AA5052) and carbon fiber reinforced polyether ether ketone composites (CF-PEEK) were fabricated by friction stir spot welding. The variance analysis revealed that the dwell time and plunge speed were the most significant factors. By optimizing the welding parameters, the ultimate tensile shear load reached 2690±64 N (the dwell time: 8 s, the plunge speed: 10 mm/min). The interface could be divided into pin-affected zone, shoulder-affected zone, resin adhesive zone and resin concentrated zone. Since resin concentrated zone could not provide interfacial bonding due to delamination, the shoulder-affected zone and pin-affected zone were decisive regions for mechanical properties. The bonding mechanism included three parts: adhesive bonding provided by re-solidified resin, macro-mechanical interlocking of aluminum alloy that entered CF-PEEK, and micro-mechanical interlocking of resin that was tightly trapped at surface slits as well as the carbon fibers beset into AA5052. This work clarifies the interfacial characteristics of AA5052/CF-PEEK hybrid joints and provides an approach to improve the mechanical properties.","PeriodicalId":18731,"journal":{"name":"Materials Processing & Manufacturing eJournal","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2021-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78191589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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