{"title":"Special Issue: The Behavior of Crystalline Materials: In Honor of Professor Hussein Zbib","authors":"","doi":"10.1115/1.4052487","DOIUrl":"https://doi.org/10.1115/1.4052487","url":null,"abstract":"","PeriodicalId":15700,"journal":{"name":"Journal of Engineering Materials and Technology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2021-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44012076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. Grigoriev, I. Kondratsky, B. Krit, V. Ludin, V. Medvetskova, N. Morozova, I. Suminov, A. Apelfeld, R. Wu
Magnesium alloys are now widely used for various purposes due to their unique properties despite the significant disadvantage associated with low corrosion resistance. The plasma-electrolytic oxidation (PEO), which allows the formation of ceramic coatings on the surface of magnesium alloys, is the most advanced and effective method for their protection. But firstly, PEO process of magnesium alloys has some difficulties, and secondly, PEO coatings affect the thermophysical characteristics of the modified materials, in particular they reduce thermal diffusivity. The presented work is devoted to the development of the technological parameters for formation of protective coating on the ultra-light alloy Mg-8Li-1Al-0.6Ce-0.3Y by the PEO method. The results analyses of electrolytes acidity and specific electrical conductivity before and after PEO process and also investigation data of the coatings structure and surface morphology are presented. An integral assessment of the ability of thermal diffusivity and corrosion resistance of the modified alloy was made. Studying of protective and thermophysical characteristics of the obtained coating showed that it provides a sufficiently high corrosion protection, despite the relatively small thickness, and the presence of pores and slightly (not more than 5%) reduces the thermal diffusivity of the magnesium ultra-light alloy.
{"title":"Protective and Thermophysical Characteristics of Plasma-Electrolytic Coatings on the Ultra-Light Magnesium Alloy","authors":"S. Grigoriev, I. Kondratsky, B. Krit, V. Ludin, V. Medvetskova, N. Morozova, I. Suminov, A. Apelfeld, R. Wu","doi":"10.1115/1.4052718","DOIUrl":"https://doi.org/10.1115/1.4052718","url":null,"abstract":"\u0000 Magnesium alloys are now widely used for various purposes due to their unique properties despite the significant disadvantage associated with low corrosion resistance. The plasma-electrolytic oxidation (PEO), which allows the formation of ceramic coatings on the surface of magnesium alloys, is the most advanced and effective method for their protection. But firstly, PEO process of magnesium alloys has some difficulties, and secondly, PEO coatings affect the thermophysical characteristics of the modified materials, in particular they reduce thermal diffusivity. The presented work is devoted to the development of the technological parameters for formation of protective coating on the ultra-light alloy Mg-8Li-1Al-0.6Ce-0.3Y by the PEO method. The results analyses of electrolytes acidity and specific electrical conductivity before and after PEO process and also investigation data of the coatings structure and surface morphology are presented. An integral assessment of the ability of thermal diffusivity and corrosion resistance of the modified alloy was made. Studying of protective and thermophysical characteristics of the obtained coating showed that it provides a sufficiently high corrosion protection, despite the relatively small thickness, and the presence of pores and slightly (not more than 5%) reduces the thermal diffusivity of the magnesium ultra-light alloy.","PeriodicalId":15700,"journal":{"name":"Journal of Engineering Materials and Technology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2021-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42353360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Rowe, Alexander J. Kaczkowski, T. Lin, G. Horn, H. Johnson
A nondestructive photoelastic method is presented for characterizing surface microcracks in monocrystalline silicon wafers, calculating the strength of the wafers, and predicting Weibull parameters under various loading conditions. Defects are first classified from through thickness infrared photoelastic images using a support vector machine learning algorithm. Characteristic wafer strength is shown to vary with the angle of applied uniaxial tensile load, showing greater strength when loaded perpendicular to the direction of wire motion than when loaded along the direction of wire motion. Observed variations in characteristic strength and Weibull shape modulus with applied tensile loading direction stem from the distribution of crack orientations and the bulk stress field acting on the microcracks. Using this method it is possible to improve manufacturing processes for silicon wafers by rapidly, accurately, and nondestructively characterizing large batches in an automated way.
{"title":"Nondestructive Photoelastic and Machine Learning Characterization of Surface Cracks and Prediction of Weibull Parameters for Photovoltaic Silicon Wafers","authors":"L. Rowe, Alexander J. Kaczkowski, T. Lin, G. Horn, H. Johnson","doi":"10.1115/1.4052673","DOIUrl":"https://doi.org/10.1115/1.4052673","url":null,"abstract":"\u0000 A nondestructive photoelastic method is presented for characterizing surface microcracks in monocrystalline silicon wafers, calculating the strength of the wafers, and predicting Weibull parameters under various loading conditions. Defects are first classified from through thickness infrared photoelastic images using a support vector machine learning algorithm. Characteristic wafer strength is shown to vary with the angle of applied uniaxial tensile load, showing greater strength when loaded perpendicular to the direction of wire motion than when loaded along the direction of wire motion. Observed variations in characteristic strength and Weibull shape modulus with applied tensile loading direction stem from the distribution of crack orientations and the bulk stress field acting on the microcracks. Using this method it is possible to improve manufacturing processes for silicon wafers by rapidly, accurately, and nondestructively characterizing large batches in an automated way.","PeriodicalId":15700,"journal":{"name":"Journal of Engineering Materials and Technology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2021-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49573524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The electrical conductivity and percolation onset of graphene-based nanocomposites are studied by varying both planar and transversal aspect ratios of graphene nanoplatelets (GNP) fillers using a three-dimensional stochastic percolation-based model. The graphene nanoplatelets are modeled as elliptical fillers to enable planar aspect ratio variations. We find that decreasing the graphite’s thickness results in an exponential performance improvement of the nanocomposites, in contrast to a linear improvement obtained when the planar aspect ratio is increased, for the same filler volume. Furthermore, we show that hybrid nanocomposites fabricated with partial replacement of GNP by carbon nanotube (CNT) may improve the electrical performance of the GNP monofiller composites. Improvement or deterioration of the electrical properties is mainly based on the morphology and content of the fillers mixed in the hybrids. Nonetheless, using a minimal amount of CNT for substitution always leads to the highest improvement in conductivity in the hybrids, while additional CNTs only lead to smaller improvement at best or even deterioration. The results are validated against experimental works and offer useful insights for the fabrication of highly conductive nanocomposites.
{"title":"Microstructural Design of Graphene Nanocomposites for Improved Electrical Conductivity","authors":"A. Gbaguidi, S. Namilae, Daewon Kim","doi":"10.1115/1.4051307","DOIUrl":"https://doi.org/10.1115/1.4051307","url":null,"abstract":"\u0000 The electrical conductivity and percolation onset of graphene-based nanocomposites are studied by varying both planar and transversal aspect ratios of graphene nanoplatelets (GNP) fillers using a three-dimensional stochastic percolation-based model. The graphene nanoplatelets are modeled as elliptical fillers to enable planar aspect ratio variations. We find that decreasing the graphite’s thickness results in an exponential performance improvement of the nanocomposites, in contrast to a linear improvement obtained when the planar aspect ratio is increased, for the same filler volume. Furthermore, we show that hybrid nanocomposites fabricated with partial replacement of GNP by carbon nanotube (CNT) may improve the electrical performance of the GNP monofiller composites. Improvement or deterioration of the electrical properties is mainly based on the morphology and content of the fillers mixed in the hybrids. Nonetheless, using a minimal amount of CNT for substitution always leads to the highest improvement in conductivity in the hybrids, while additional CNTs only lead to smaller improvement at best or even deterioration. The results are validated against experimental works and offer useful insights for the fabrication of highly conductive nanocomposites.","PeriodicalId":15700,"journal":{"name":"Journal of Engineering Materials and Technology-transactions of The Asme","volume":"22 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91218929","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
S. A. Raza, M. Khan, M. R. A. Karim, R. Ali, M. Naseer, S. Z. Abbas, M. Ahmad
Equiatomic TiNi alloy composites, reinforced with 0, 5, 10, and 15 vol% ZrO2, were synthesized using conventional sintering approach. Equiatomic TiNi pre-alloyed powder and ZrO2 powder were mixed in planetary ball mill for 6 h followed by cold compaction and pressure-less sintering, respectively. The sintered density was found to vary inversely with the addition of ZrO2 content. The X-ray diffraction (XRD) spectra have shown the formation of multiple-phases which were resulted from the decomposition of the B19′ and B2 phases of the equiatomic TiNi alloy due to the addition of ZrO2 and higher diffusion rate of Ni than that of Ti in the alloy composite. An increase in hardness was noted due to the addition of ZrO2, measured by micro and nanoindentation techniques. Potentiodynamic polarization scan revealed a 10% decrease in the corrosion rate of the composite containing 10 vol% ZrO2. Electrochemical impedance spectroscopy (EIS) results indicated an increase in passive layer resistance (Rcoat) due to the increase in charge transfer resistance (Rct) caused by the reduced leaching of ions from the surface.
{"title":"Effect of Zirconium Oxide Reinforcement on Microstructural, Electrochemical, and Mechanical Properties of TiNi Alloy Produced via Powder Metallurgy Route","authors":"S. A. Raza, M. Khan, M. R. A. Karim, R. Ali, M. Naseer, S. Z. Abbas, M. Ahmad","doi":"10.1115/1.4051308","DOIUrl":"https://doi.org/10.1115/1.4051308","url":null,"abstract":"\u0000 Equiatomic TiNi alloy composites, reinforced with 0, 5, 10, and 15 vol% ZrO2, were synthesized using conventional sintering approach. Equiatomic TiNi pre-alloyed powder and ZrO2 powder were mixed in planetary ball mill for 6 h followed by cold compaction and pressure-less sintering, respectively. The sintered density was found to vary inversely with the addition of ZrO2 content. The X-ray diffraction (XRD) spectra have shown the formation of multiple-phases which were resulted from the decomposition of the B19′ and B2 phases of the equiatomic TiNi alloy due to the addition of ZrO2 and higher diffusion rate of Ni than that of Ti in the alloy composite. An increase in hardness was noted due to the addition of ZrO2, measured by micro and nanoindentation techniques. Potentiodynamic polarization scan revealed a 10% decrease in the corrosion rate of the composite containing 10 vol% ZrO2. Electrochemical impedance spectroscopy (EIS) results indicated an increase in passive layer resistance (Rcoat) due to the increase in charge transfer resistance (Rct) caused by the reduced leaching of ions from the surface.","PeriodicalId":15700,"journal":{"name":"Journal of Engineering Materials and Technology-transactions of The Asme","volume":"25 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86030362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Noha M. Hassan, M. Antar, Natalie Saleem, Sara Aboukhelil, Lina Ghonim
Fabrication of Functionally Graded Metal Matrix Composites (FGMMC) especially with high ceramic reinforcement's volume fraction is highly challenging. Depending on the processing technique and process parameters various defects may arise. This research aims to find the best procedure to make FGMMCs with the highest quality and minimum cost. A new method is proposed that incorporates lost-foam and melt infiltration with semicentrifugal casting to produce FGMMC. Experiments were performed to in-situ fabricate 6061-Aluminum alloy reinforced with gradient distributed Silicon carbide particles (Al/SiC FGMMC). Effect of SiC %, Al pouring temperature and rotational speed on the fabricated specimens hardness and reinforcement gradient were investigated using design of experiments and regression analysis. Results reveal the optimum procedure and process settings based on desired properties/gradient required. Mathematical model formulated captures the effect of these process parameters on process cost, and cost of poor quality. Improper selection of those parameters may lead to extensive losses due cost of poor quality which is 12 times higher than the material cost. The proposed manufacturing process proved satisfactory in ensuring proper dispersion. A desirability function can by used to determine the process parameters and volume fraction that minimizes the defects and gives superior properties for a specific application.
{"title":"Effect of Synthesis Procedure on Particle Dispersion and Hardness of Al- Sic Functionally Graded Metal Matrix Composite","authors":"Noha M. Hassan, M. Antar, Natalie Saleem, Sara Aboukhelil, Lina Ghonim","doi":"10.1115/1.4052631","DOIUrl":"https://doi.org/10.1115/1.4052631","url":null,"abstract":"\u0000 Fabrication of Functionally Graded Metal Matrix Composites (FGMMC) especially with high ceramic reinforcement's volume fraction is highly challenging. Depending on the processing technique and process parameters various defects may arise. This research aims to find the best procedure to make FGMMCs with the highest quality and minimum cost. A new method is proposed that incorporates lost-foam and melt infiltration with semicentrifugal casting to produce FGMMC. Experiments were performed to in-situ fabricate 6061-Aluminum alloy reinforced with gradient distributed Silicon carbide particles (Al/SiC FGMMC). Effect of SiC %, Al pouring temperature and rotational speed on the fabricated specimens hardness and reinforcement gradient were investigated using design of experiments and regression analysis. Results reveal the optimum procedure and process settings based on desired properties/gradient required. Mathematical model formulated captures the effect of these process parameters on process cost, and cost of poor quality. Improper selection of those parameters may lead to extensive losses due cost of poor quality which is 12 times higher than the material cost. The proposed manufacturing process proved satisfactory in ensuring proper dispersion. A desirability function can by used to determine the process parameters and volume fraction that minimizes the defects and gives superior properties for a specific application.","PeriodicalId":15700,"journal":{"name":"Journal of Engineering Materials and Technology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44927486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, chromium electroplating process, corresponding hydrogen embrittlement, and the effects of baking on hydrogen diffusion are investigated. Three types of materials in the form of Raw 4340 steel, Chromium electroplated 4340 steel, and Chromium electroplated and baked 4340 steel are used in order to shed light on the aforementioned processes. Mechanical and microstructural analyses are carried out to observe the effects of hydrogen diffusion. Mechanical analyses show that the tensile strength and hardness of the specimens deteriorate after the chrome-electroplating process due to the presence of atomic hydrogen. X-ray diffraction (XRD) analyses are carried out for material characterization. Microstructural analyses reveal that hydrogen enters into the material with chromium electroplating process, and baking after chromium electroplating process is an effective way to prevent hydrogen embrittlement. Additionally, the effects of hydrogen on the tensile response of α-Fe-based microstructure with a similar chemical composition of alloying elements are simulated through molecular dynamics (MD) method.
{"title":"Experimental and Molecular Dynamics Simulation-Based Investigations on Hydrogen Embrittlement Behavior of Chromium Electroplated 4340 Steel","authors":"Ozge Dogan, M. F. Kapci, V. Esat, B. Bal","doi":"10.1115/1.4051400","DOIUrl":"https://doi.org/10.1115/1.4051400","url":null,"abstract":"\u0000 In this study, chromium electroplating process, corresponding hydrogen embrittlement, and the effects of baking on hydrogen diffusion are investigated. Three types of materials in the form of Raw 4340 steel, Chromium electroplated 4340 steel, and Chromium electroplated and baked 4340 steel are used in order to shed light on the aforementioned processes. Mechanical and microstructural analyses are carried out to observe the effects of hydrogen diffusion. Mechanical analyses show that the tensile strength and hardness of the specimens deteriorate after the chrome-electroplating process due to the presence of atomic hydrogen. X-ray diffraction (XRD) analyses are carried out for material characterization. Microstructural analyses reveal that hydrogen enters into the material with chromium electroplating process, and baking after chromium electroplating process is an effective way to prevent hydrogen embrittlement. Additionally, the effects of hydrogen on the tensile response of α-Fe-based microstructure with a similar chemical composition of alloying elements are simulated through molecular dynamics (MD) method.","PeriodicalId":15700,"journal":{"name":"Journal of Engineering Materials and Technology-transactions of The Asme","volume":"52 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88518523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Utzeri, A. Bhagavatam, E. Mancini, G. Dinda, M. Sasso, G. Newaz
Laser metal deposition (LMD) is an additive manufacturing process with an extreme potential in large-scale metal production. Among the printable metals, the Inconel 625 has found a wide variety of cutting-edge applications in the aerospace, defense, and space sectors. Thus, knowledge of mechanical properties under quasi-static and dynamic conditions is fundamental. In this work, the quasi-static and dynamic compression behavior of Inconel 625 obtained by LMD is presented. The curves of printed Inconel 625 showed a change in slope in the work hardening phase, which is due to the mechanics of the dislocation motion. Therefore, a modified two-stage (TS) Hollomon power-law is proposed to model this specific mechanical behavior, which identifies a threshold strain that delimit two different hardening behaviors. Furthermore, Johnson–Cook and Cowper–Symonds models were used to represent the effect of strain rate and temperature on the material properties. A variable strain rate sensitivity along the compression strain was found. Hence, double sensitivity terms were introduced into the TS Hollomon power-law, allowing to reproduce the dynamic behavior of Inconel 625.
{"title":"Quasi-Static and Dynamic Behavior of Inconel 625 Obtained by Laser Metal Deposition: Experimental Characterization and Constitutive Modeling","authors":"M. Utzeri, A. Bhagavatam, E. Mancini, G. Dinda, M. Sasso, G. Newaz","doi":"10.1115/1.4051087","DOIUrl":"https://doi.org/10.1115/1.4051087","url":null,"abstract":"\u0000 Laser metal deposition (LMD) is an additive manufacturing process with an extreme potential in large-scale metal production. Among the printable metals, the Inconel 625 has found a wide variety of cutting-edge applications in the aerospace, defense, and space sectors. Thus, knowledge of mechanical properties under quasi-static and dynamic conditions is fundamental. In this work, the quasi-static and dynamic compression behavior of Inconel 625 obtained by LMD is presented. The curves of printed Inconel 625 showed a change in slope in the work hardening phase, which is due to the mechanics of the dislocation motion. Therefore, a modified two-stage (TS) Hollomon power-law is proposed to model this specific mechanical behavior, which identifies a threshold strain that delimit two different hardening behaviors. Furthermore, Johnson–Cook and Cowper–Symonds models were used to represent the effect of strain rate and temperature on the material properties. A variable strain rate sensitivity along the compression strain was found. Hence, double sensitivity terms were introduced into the TS Hollomon power-law, allowing to reproduce the dynamic behavior of Inconel 625.","PeriodicalId":15700,"journal":{"name":"Journal of Engineering Materials and Technology-transactions of The Asme","volume":"12 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88670240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many metals and alloys have a stress exponent for the creep rate that is considerably higher than the value of three that is typically predicted by creep recovery models. One example is pure Ni. Creep data from Norman and Duran that are analyzed in the paper give a stress exponent of about seven in the temperature range 0.3–0.55 of the melting point. It has recently been shown that the high creep exponent of Al and Cu in the power-law breakdown regime can be explained by the presence of strain-induced vacancies. By applying a creep recovery model that does not involve adjustable parameters, it is shown that strain-induced vacancies can also explain the high-stress exponent of pure nickel.
{"title":"Modeling the Creep of Nickel","authors":"R. Sandström, Jing Zhang","doi":"10.1115/1.4051421","DOIUrl":"https://doi.org/10.1115/1.4051421","url":null,"abstract":"\u0000 Many metals and alloys have a stress exponent for the creep rate that is considerably higher than the value of three that is typically predicted by creep recovery models. One example is pure Ni. Creep data from Norman and Duran that are analyzed in the paper give a stress exponent of about seven in the temperature range 0.3–0.55 of the melting point. It has recently been shown that the high creep exponent of Al and Cu in the power-law breakdown regime can be explained by the presence of strain-induced vacancies. By applying a creep recovery model that does not involve adjustable parameters, it is shown that strain-induced vacancies can also explain the high-stress exponent of pure nickel.","PeriodicalId":15700,"journal":{"name":"Journal of Engineering Materials and Technology-transactions of The Asme","volume":"2 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2021-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75542105","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jean-Franco̧is Croteau, Guillaume Robin, E. Cantergiani, S. Atieh, N. Jacques, G. Mazars, M. Martiny
The forming limit diagram of high-purity niobium sheets used for the manufacturing of superconducting radiofrequency (SRF) cavities is presented. The Marciniak (in-plane) test was used with niobium blanks with a thickness of 1 mm and blank carriers of annealed oxygen-free electronic copper. A high formability was measured, with an approximate true major strain at necking for plane-strain of 0.441. The high formability of high-purity niobium is likely caused by its high strain rate sensitivity of 0.112. Plastic strain anisotropies (r-values) of 1.66, 1.00, and 2.30 were measured in the 0°, 45°, and 90° directions. However, stress–strain curves at a nominal strain rate of ~10−3 s−1 showed similar mechanical properties in the three directions. Theoretical calculations of the forming limit curves (FLCs) were conducted using an analytical two-zone model. The obtained results indicate that the anisotropy and strain rate sensitivity of niobium affect its formability. The model was used to investigate the influence of strain rate on strains at necking. The obtained results suggest that the use of high-speed sheet forming should further increase the formability of niobium.
{"title":"Characterization of the Formability of High-Purity Polycrystalline Niobium Sheets for SRF Applications","authors":"Jean-Franco̧is Croteau, Guillaume Robin, E. Cantergiani, S. Atieh, N. Jacques, G. Mazars, M. Martiny","doi":"10.1115/1.4052557","DOIUrl":"https://doi.org/10.1115/1.4052557","url":null,"abstract":"\u0000 The forming limit diagram of high-purity niobium sheets used for the manufacturing of superconducting radiofrequency (SRF) cavities is presented. The Marciniak (in-plane) test was used with niobium blanks with a thickness of 1 mm and blank carriers of annealed oxygen-free electronic copper. A high formability was measured, with an approximate true major strain at necking for plane-strain of 0.441. The high formability of high-purity niobium is likely caused by its high strain rate sensitivity of 0.112. Plastic strain anisotropies (r-values) of 1.66, 1.00, and 2.30 were measured in the 0°, 45°, and 90° directions. However, stress–strain curves at a nominal strain rate of ~10−3 s−1 showed similar mechanical properties in the three directions. Theoretical calculations of the forming limit curves (FLCs) were conducted using an analytical two-zone model. The obtained results indicate that the anisotropy and strain rate sensitivity of niobium affect its formability. The model was used to investigate the influence of strain rate on strains at necking. The obtained results suggest that the use of high-speed sheet forming should further increase the formability of niobium.","PeriodicalId":15700,"journal":{"name":"Journal of Engineering Materials and Technology-transactions of The Asme","volume":" ","pages":""},"PeriodicalIF":1.2,"publicationDate":"2021-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41485710","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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