Yu Qiu, Yuansong Zeng, Qiang Meng, Wei Guan, Jihong Dong, Huaxia Zhao, Lei Cui, Xuepiao Bai, Mingtao Wang
The softening of aluminum–lithium alloy welded joints generally leads to a reduction in mechanical properties. In this study, a piece of 2A97-T3 aluminum–lithium alloy with a thickness of 2.8 mm was selected as the test material, and the tool and process used for wire-filled stationary shoulder friction stir welding (SSFSW) were developed. By increasing the bearing area of the softening zone, an equal-strength T-joint was manufactured. Good weld formation was obtained when the rotation speed was set to 2000 rpm and the welding speed ranged from 100 to 120 mm/min. The thickness of the softening zone was controlled by adjusting the reserved gap between the shoulder and the workpiece. The softening mechanism of the weld joint was revealed. The softening was attributed to the coarsening of the main precipitated phases (T1 and θ′ phases) in the heat-affected zone (HAZ) and the dissolution of precipitated phases in the thermo-mechanically affected zone (TMAZ). Grain refinement in the nugget zone (NZ) led to a certain fine-grained strengthening effect, although the precipitated phase was almost completely dissolved. Due to the thermal effect of second-pass welding, the hardness value of the NZ and HAZ in the center of the skin further decreased, and the minimum hardness was approximately 70% that of the base material. Tensile testing results indicated that the softening effect was largely offset by the increased bearing area of the softening zone, resulting in the successful welding of high-strength Al-Li alloy T-joints with equal strength. The strength coefficient was found to be 0.977.
{"title":"Study on the Optimization of the Tensile Properties of an Al-Li Alloy Friction Stir-Welding T-Joint","authors":"Yu Qiu, Yuansong Zeng, Qiang Meng, Wei Guan, Jihong Dong, Huaxia Zhao, Lei Cui, Xuepiao Bai, Mingtao Wang","doi":"10.3390/met14091040","DOIUrl":"https://doi.org/10.3390/met14091040","url":null,"abstract":"The softening of aluminum–lithium alloy welded joints generally leads to a reduction in mechanical properties. In this study, a piece of 2A97-T3 aluminum–lithium alloy with a thickness of 2.8 mm was selected as the test material, and the tool and process used for wire-filled stationary shoulder friction stir welding (SSFSW) were developed. By increasing the bearing area of the softening zone, an equal-strength T-joint was manufactured. Good weld formation was obtained when the rotation speed was set to 2000 rpm and the welding speed ranged from 100 to 120 mm/min. The thickness of the softening zone was controlled by adjusting the reserved gap between the shoulder and the workpiece. The softening mechanism of the weld joint was revealed. The softening was attributed to the coarsening of the main precipitated phases (T1 and θ′ phases) in the heat-affected zone (HAZ) and the dissolution of precipitated phases in the thermo-mechanically affected zone (TMAZ). Grain refinement in the nugget zone (NZ) led to a certain fine-grained strengthening effect, although the precipitated phase was almost completely dissolved. Due to the thermal effect of second-pass welding, the hardness value of the NZ and HAZ in the center of the skin further decreased, and the minimum hardness was approximately 70% that of the base material. Tensile testing results indicated that the softening effect was largely offset by the increased bearing area of the softening zone, resulting in the successful welding of high-strength Al-Li alloy T-joints with equal strength. The strength coefficient was found to be 0.977.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142184880","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Elena Gachegova, Denis Davydov, Sergey Mironov, Alexander Kalinenko, Maxim Ozerov, Sergey Zherebtsov, Oleg Plekhov
Laser shock peening (LSP) is a relatively novel and promising surface hardening method. An absorbing layer, which is needed to protect the specimen surface from undesirable thermal effects caused by laser irradiation, should be considered as one of many varying parameters. The physical characteristics of the coating and its adhesion to the specimen surface can significantly influence the result of LSP. In this study, three commonly used absorbing coatings, namely black polyvinylchloride tape with a sticky layer, aluminum foil, and black alkyd paint were used to cover three-millimeter-thick plates of the Ti-6Al-4V titanium alloy with globular or lamellar microstructures. LSP of one side of the plates was carried out with a power density of 10 GW/cm2. The hole drilling method was used to evaluate residual stresses. The aluminum foil was found to be the optimal option for LSP of the Ti-6Al-4V titanium alloy. Microstructural investigations carried out using EBSD analysis suggested that no significant reduction in grain size, twinning, or dislocation density growth occurred as a result of LSP irrespective of the initial structure.
{"title":"The Influence of Absorbing Coating Material on the Efficiency of Laser Shock Peening","authors":"Elena Gachegova, Denis Davydov, Sergey Mironov, Alexander Kalinenko, Maxim Ozerov, Sergey Zherebtsov, Oleg Plekhov","doi":"10.3390/met14091045","DOIUrl":"https://doi.org/10.3390/met14091045","url":null,"abstract":"Laser shock peening (LSP) is a relatively novel and promising surface hardening method. An absorbing layer, which is needed to protect the specimen surface from undesirable thermal effects caused by laser irradiation, should be considered as one of many varying parameters. The physical characteristics of the coating and its adhesion to the specimen surface can significantly influence the result of LSP. In this study, three commonly used absorbing coatings, namely black polyvinylchloride tape with a sticky layer, aluminum foil, and black alkyd paint were used to cover three-millimeter-thick plates of the Ti-6Al-4V titanium alloy with globular or lamellar microstructures. LSP of one side of the plates was carried out with a power density of 10 GW/cm2. The hole drilling method was used to evaluate residual stresses. The aluminum foil was found to be the optimal option for LSP of the Ti-6Al-4V titanium alloy. Microstructural investigations carried out using EBSD analysis suggested that no significant reduction in grain size, twinning, or dislocation density growth occurred as a result of LSP irrespective of the initial structure.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142184912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Complex concentrated alloys, including high-entropy alloys (HEAs) and medium-entropy alloys (MEAs), offer another pathway for developing metals with excellent mechanical properties. However, HEAs/MEAs of different structures often suffer from various drawbacks. So, investigations on the effect of phase and microstructure on their properties become necessary. In the present work, we adjust the phase constitution and microstructure by Al addition in a series of (Ti2ZrHf)100−xAlx (x = 12, 14, 16, 18, 20, at.%, named Alx) MEAs. Different from traditional titanium, Al shows a β-stabilizing effect, and the phase follows the evolution of α′(α)→α″→β + ω + B2 with Al increasing from 12 to 20 at.%, which could not be predicted by the CALPHAD (Calculate Phase Diagrams) method or the Bo-Md diagram because of the complex interactions among composition elements. At a low Al content, the solid solution strengthening of the HCP phase contributes to the extremely high strength with a σ0.2 of 1528 MPa and σb of 1937 MPa for Al14. The appearance of α″ deteriorates the deformation capability with increasing Al content in the Al16 and Al18 MEAs. In the Al20 MEA, Al improves the formations of ordered B2 and metastable β. The phase transformation strengthening, including B2 to BCC and BCC to α″, together with the precipitation strengthening of ω, brings about a high work-hardening ratio (above 5 GPa) and improvements in ductility (6.8% elongation). This work provides guidelines for optimizing the properties of MEAs.
{"title":"Abnormal Effect of Al on the Phase Stability and Deformation Mechanism of Ti-Zr-Hf-Al Medium-Entropy Alloys","authors":"Penghao Yuan, Lu Wang, Ying Liu, Xidong Hui","doi":"10.3390/met14091035","DOIUrl":"https://doi.org/10.3390/met14091035","url":null,"abstract":"Complex concentrated alloys, including high-entropy alloys (HEAs) and medium-entropy alloys (MEAs), offer another pathway for developing metals with excellent mechanical properties. However, HEAs/MEAs of different structures often suffer from various drawbacks. So, investigations on the effect of phase and microstructure on their properties become necessary. In the present work, we adjust the phase constitution and microstructure by Al addition in a series of (Ti2ZrHf)100−xAlx (x = 12, 14, 16, 18, 20, at.%, named Alx) MEAs. Different from traditional titanium, Al shows a β-stabilizing effect, and the phase follows the evolution of α′(α)→α″→β + ω + B2 with Al increasing from 12 to 20 at.%, which could not be predicted by the CALPHAD (Calculate Phase Diagrams) method or the Bo-Md diagram because of the complex interactions among composition elements. At a low Al content, the solid solution strengthening of the HCP phase contributes to the extremely high strength with a σ0.2 of 1528 MPa and σb of 1937 MPa for Al14. The appearance of α″ deteriorates the deformation capability with increasing Al content in the Al16 and Al18 MEAs. In the Al20 MEA, Al improves the formations of ordered B2 and metastable β. The phase transformation strengthening, including B2 to BCC and BCC to α″, together with the precipitation strengthening of ω, brings about a high work-hardening ratio (above 5 GPa) and improvements in ductility (6.8% elongation). This work provides guidelines for optimizing the properties of MEAs.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142184916","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ilaria Capasso, Francesca Romana Andreacola, Giuseppe Brando
Additive manufacturing, better known as 3D printing, is an innovative manufacturing technique which allows the production of parts, with complex and challenging shapes, layer by layer mainly through melting powder particles (metallic, polymeric, or composite) or extruding material in the form of wire, depending on the specific technique. Three-dimensional printing is already widely employed in several sectors, especially aerospace and automotive, although its large-scale use still requires the gain of know-how and to overcome certain limitations related to the production process and high costs. In particular, this innovative technology aims to overtake some of the shortcomings of conventional production methods and to obtain many additional advantages, such as reduction in material consumption and waste production, high level of customisation and automation, environmental sustainability, great design freedom, and reduction in stockpiles. This article aims to give a detailed review of the state of scientific research and progress in the industrial field of metal additive manufacturing, with a detailed view to its potential use in civil engineering and construction. After a comprehensive overview of the current most adopted additive manufacturing techniques, the fundamental printing process parameters to achieve successful results in terms of quality, precision, and strength are debated. Then, the already existing applications of metal 3D printing in the field of construction and civil engineering are widely discussed. Moreover, the strategic potentiality of the use of additive manufacturing both combined with topological optimisation and for the eventual repair of existing structures is presented. It can be stated that the discussed findings led us to conclude that the use of metal additive manufacturing in the building sector is very promising because of the several benefits that this technology is able to offer.
{"title":"Additive Manufacturing of Metal Materials for Construction Engineering: An Overview on Technologies and Applications","authors":"Ilaria Capasso, Francesca Romana Andreacola, Giuseppe Brando","doi":"10.3390/met14091033","DOIUrl":"https://doi.org/10.3390/met14091033","url":null,"abstract":"Additive manufacturing, better known as 3D printing, is an innovative manufacturing technique which allows the production of parts, with complex and challenging shapes, layer by layer mainly through melting powder particles (metallic, polymeric, or composite) or extruding material in the form of wire, depending on the specific technique. Three-dimensional printing is already widely employed in several sectors, especially aerospace and automotive, although its large-scale use still requires the gain of know-how and to overcome certain limitations related to the production process and high costs. In particular, this innovative technology aims to overtake some of the shortcomings of conventional production methods and to obtain many additional advantages, such as reduction in material consumption and waste production, high level of customisation and automation, environmental sustainability, great design freedom, and reduction in stockpiles. This article aims to give a detailed review of the state of scientific research and progress in the industrial field of metal additive manufacturing, with a detailed view to its potential use in civil engineering and construction. After a comprehensive overview of the current most adopted additive manufacturing techniques, the fundamental printing process parameters to achieve successful results in terms of quality, precision, and strength are debated. Then, the already existing applications of metal 3D printing in the field of construction and civil engineering are widely discussed. Moreover, the strategic potentiality of the use of additive manufacturing both combined with topological optimisation and for the eventual repair of existing structures is presented. It can be stated that the discussed findings led us to conclude that the use of metal additive manufacturing in the building sector is very promising because of the several benefits that this technology is able to offer.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142184914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tuo Li, Chuanchuan Ma, Chun Xue, Hailian Gui, Meirong Shuai, Zhibing Chu
JCOE is a progressively advanced forming process that encompasses J-forming, C-forming, O-forming, and expansion technology. This methodology constitutes an efficacious means of producing high-strength pipes. In recent years, this process has been utilized in the manufacturing of small-diameter, thick-walled welded pipes using nickel-based alloy N08810 plates. This study establishes a mathematical model for key parameters in the pre-bending process, rooted in JCOE forming and plastic bending theory, and introduces a process optimization approach. Initially, by refining the mold configuration and executing simulation analyses, we comprehensively delineate the stress–strain distribution and metal flow dynamics during pre-bending. Furthermore, we unravel the influence of varying plate thicknesses on both the pre-bending force and springback bending angle. Ultimately, the veracity of our theoretical model and simulation protocol is substantiated through rigorous experimentation. The findings indicate that the optimized mold configuration yields superior pre-bending forces and springback bending angles compared to conventional methods, thereby furnishing a solid theoretical foundation for industrial applications.
{"title":"Study on the Influence of Thickness on the Pre-Bending Process of the JCOE Forming Plate Edge of Nickel-Based Alloy N08810","authors":"Tuo Li, Chuanchuan Ma, Chun Xue, Hailian Gui, Meirong Shuai, Zhibing Chu","doi":"10.3390/met14091032","DOIUrl":"https://doi.org/10.3390/met14091032","url":null,"abstract":"JCOE is a progressively advanced forming process that encompasses J-forming, C-forming, O-forming, and expansion technology. This methodology constitutes an efficacious means of producing high-strength pipes. In recent years, this process has been utilized in the manufacturing of small-diameter, thick-walled welded pipes using nickel-based alloy N08810 plates. This study establishes a mathematical model for key parameters in the pre-bending process, rooted in JCOE forming and plastic bending theory, and introduces a process optimization approach. Initially, by refining the mold configuration and executing simulation analyses, we comprehensively delineate the stress–strain distribution and metal flow dynamics during pre-bending. Furthermore, we unravel the influence of varying plate thicknesses on both the pre-bending force and springback bending angle. Ultimately, the veracity of our theoretical model and simulation protocol is substantiated through rigorous experimentation. The findings indicate that the optimized mold configuration yields superior pre-bending forces and springback bending angles compared to conventional methods, thereby furnishing a solid theoretical foundation for industrial applications.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142184913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The damage to the shear-punched surface layers such as strain-hardening, strain-induced martensite transformation, and micro-void initiation behaviors was evaluated in the third-generation low-carbon advanced ultrahigh-strength TRIP-aided bainitic ferrite (TBF), bainitic ferrite–martensite (TBM), and martensite (TM) steels. In addition, the surface layer damage was related to (1) the mean normal stress generated during shear-punching and (2) microstructural properties such as the matrix structure, retained austenite characteristics, and second-phase properties. The shear-punched surface layer damage was produced under the mean normal stress between zero and negative in all the steels. The TBM and TM steels achieved relatively small surface layer damage. The small surface layer damage resulted in excellent cold stretch-flangeability, with a high crack-propagation/void-connection resistance on hole expansion.
{"title":"Evaluation of Shear-Punched Surface Layer Damage in Ultrahigh-Strength TRIP-Aided Steels with Bainitic Ferrite and/or Martensite Matrix Structure","authors":"Koh-ichi Sugimoto, Shoya Shioiri, Junya Kobayashi, Tomohiko Hojo","doi":"10.3390/met14091034","DOIUrl":"https://doi.org/10.3390/met14091034","url":null,"abstract":"The damage to the shear-punched surface layers such as strain-hardening, strain-induced martensite transformation, and micro-void initiation behaviors was evaluated in the third-generation low-carbon advanced ultrahigh-strength TRIP-aided bainitic ferrite (TBF), bainitic ferrite–martensite (TBM), and martensite (TM) steels. In addition, the surface layer damage was related to (1) the mean normal stress generated during shear-punching and (2) microstructural properties such as the matrix structure, retained austenite characteristics, and second-phase properties. The shear-punched surface layer damage was produced under the mean normal stress between zero and negative in all the steels. The TBM and TM steels achieved relatively small surface layer damage. The small surface layer damage resulted in excellent cold stretch-flangeability, with a high crack-propagation/void-connection resistance on hole expansion.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142184915","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The continuous retained-mandrel rolling process is a promising method for titanium tube production with high efficiency and a short process. The importance of mandrel as a deformation tool supporting the inner wall is crucial. This paper thoroughly examines the influence of mandrel velocity on the deformation characteristics at the groove vertex using three approaches: numerical simulation, shear-deformation observation experiments, and microstructure analysis. The following conclusions are drawn: Decreasing the mandrel velocity enhances the penetration of shear deformation into the inner wall of the titanium tube, improves thickness uniformity, and shifts the deformation mechanism near the inner wall from twinning to dislocation slip. As a result, the volume fraction of recrystallization increases from 18.4% to 42.3%. However, the mean shear strain increases first and then decreases to a certain value as the mandrel speed decreases, which is attributed to the combined influence of the cross-shear zone and the rolling force.
{"title":"Study on the Influence of Mandrel Speed on the Titanium Tube Continuous Retained-Mandrel Rolling Process","authors":"Chao Li, Yuanhua Shuang, Jianxun Chen, Tao Wu","doi":"10.3390/met14091024","DOIUrl":"https://doi.org/10.3390/met14091024","url":null,"abstract":"The continuous retained-mandrel rolling process is a promising method for titanium tube production with high efficiency and a short process. The importance of mandrel as a deformation tool supporting the inner wall is crucial. This paper thoroughly examines the influence of mandrel velocity on the deformation characteristics at the groove vertex using three approaches: numerical simulation, shear-deformation observation experiments, and microstructure analysis. The following conclusions are drawn: Decreasing the mandrel velocity enhances the penetration of shear deformation into the inner wall of the titanium tube, improves thickness uniformity, and shifts the deformation mechanism near the inner wall from twinning to dislocation slip. As a result, the volume fraction of recrystallization increases from 18.4% to 42.3%. However, the mean shear strain increases first and then decreases to a certain value as the mandrel speed decreases, which is attributed to the combined influence of the cross-shear zone and the rolling force.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142184917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Felix Trauter, Ralf Loeffler, Gerhard Schneider, Dagmar Goll
For permanent magnetic materials, anisotropic microstructures are crucial for maximizing remanence Jr and maximum energy product (BH)max. This also applies to additive manufacturing processes such as laser powder bed fusion (PBF-LB). In PBF-LB processing, the solidification behavior is determined by the crystal structure of the material, the substrate, and the melt-pool morphology, resulting from the laser power PL and scanning speed vs. To study the impact of these parameters on the textured growth of grains in the melt-pool, experiments were conducted using single laser tracks on (CoCuFeZr)17Sm2 sintered magnets. A method was developed to quantify this grain shape anisotropy from electron backscatter diffraction (EBSD) analysis. For all grains in the melt-pool, the grain shape aspect ratio (GSAR) is calculated to distinguish columnar (GSAR < 0.5) and equiaxed (GSAR > 0.5) grains. For columnar grains, the grain shape orientation (GSO) is determined. The GSO represents the preferred growth direction of each grain. This method can also be used to reconstruct the temperature gradients present during solidification in the melt-pool. A dependence of the melt-pool aspect ratio (depth/width) on energy input was observed, where increasing energy input (increasing PL, decreasing vs) led to higher aspect ratios. For aspect ratios around 0.3, an optimum for directional columnar growth (93% area fraction) with predominantly vertical growth direction (mean angular deviation of 23.1° from vertical) was observed. The resulting crystallographic orientation is beyond the scope of this publication and will be investigated in future work.
{"title":"Shape Anisotropy of Grains Formed by Laser Melting of (CoCuFeZr)17Sm2","authors":"Felix Trauter, Ralf Loeffler, Gerhard Schneider, Dagmar Goll","doi":"10.3390/met14091025","DOIUrl":"https://doi.org/10.3390/met14091025","url":null,"abstract":"For permanent magnetic materials, anisotropic microstructures are crucial for maximizing remanence Jr and maximum energy product (BH)max. This also applies to additive manufacturing processes such as laser powder bed fusion (PBF-LB). In PBF-LB processing, the solidification behavior is determined by the crystal structure of the material, the substrate, and the melt-pool morphology, resulting from the laser power PL and scanning speed vs. To study the impact of these parameters on the textured growth of grains in the melt-pool, experiments were conducted using single laser tracks on (CoCuFeZr)17Sm2 sintered magnets. A method was developed to quantify this grain shape anisotropy from electron backscatter diffraction (EBSD) analysis. For all grains in the melt-pool, the grain shape aspect ratio (GSAR) is calculated to distinguish columnar (GSAR < 0.5) and equiaxed (GSAR > 0.5) grains. For columnar grains, the grain shape orientation (GSO) is determined. The GSO represents the preferred growth direction of each grain. This method can also be used to reconstruct the temperature gradients present during solidification in the melt-pool. A dependence of the melt-pool aspect ratio (depth/width) on energy input was observed, where increasing energy input (increasing PL, decreasing vs) led to higher aspect ratios. For aspect ratios around 0.3, an optimum for directional columnar growth (93% area fraction) with predominantly vertical growth direction (mean angular deviation of 23.1° from vertical) was observed. The resulting crystallographic orientation is beyond the scope of this publication and will be investigated in future work.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142184918","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhibin Xing, Lingwei Kong, Lei Pang, Xu Liu, Kunyang Ma, Wenbo Wu, Peng Li
The aggregation and evolution of dislocations form different configurations, which are the preferred locations for fatigue crack initiation. To analyze the spatial distribution of the same dislocation configuration and the resulting configuration morphologies on different observation planes, several typical hysteresis loops and dislocation configurations in fatigued face-centered cubic single crystals with various orientations were compared. The crystal orientations of these specimens were determined by the electron back-scattering diffraction technique in a Cambridge S360 Scanning Electron Microscope. It is well known that dislocation ladder and wall structures, as well as patch and vein structures, are distributed on their respective observation planes, (12¯1) and (111). These correspond to the point defect direction and line defect direction of dislocations, respectively. Therefore, the wall structures on the (12¯1) and (111) planes consist of point defects and line defects, which can be defined as point walls and line walls, respectively. Furthermore, the walls on the (12¯1) plane consist of Persistent Slip Band ladders connected with each other, corresponding to the formation of deformation bands. The evolution of dislocation patterns follows a process from patch to ladder and from vein to wall. The formation of labyrinths and dislocation cells originates from the activation of different secondary slip systems. In one word, it can help us better understand the physical nature of metal fatigue and failure by studying the distribution and evolution of different configurations.
{"title":"Comparison on Hysteresis Loops and Dislocation Configurations in Fatigued Face-Centered Cubic Single Crystals","authors":"Zhibin Xing, Lingwei Kong, Lei Pang, Xu Liu, Kunyang Ma, Wenbo Wu, Peng Li","doi":"10.3390/met14091023","DOIUrl":"https://doi.org/10.3390/met14091023","url":null,"abstract":"The aggregation and evolution of dislocations form different configurations, which are the preferred locations for fatigue crack initiation. To analyze the spatial distribution of the same dislocation configuration and the resulting configuration morphologies on different observation planes, several typical hysteresis loops and dislocation configurations in fatigued face-centered cubic single crystals with various orientations were compared. The crystal orientations of these specimens were determined by the electron back-scattering diffraction technique in a Cambridge S360 Scanning Electron Microscope. It is well known that dislocation ladder and wall structures, as well as patch and vein structures, are distributed on their respective observation planes, (12¯1) and (111). These correspond to the point defect direction and line defect direction of dislocations, respectively. Therefore, the wall structures on the (12¯1) and (111) planes consist of point defects and line defects, which can be defined as point walls and line walls, respectively. Furthermore, the walls on the (12¯1) plane consist of Persistent Slip Band ladders connected with each other, corresponding to the formation of deformation bands. The evolution of dislocation patterns follows a process from patch to ladder and from vein to wall. The formation of labyrinths and dislocation cells originates from the activation of different secondary slip systems. In one word, it can help us better understand the physical nature of metal fatigue and failure by studying the distribution and evolution of different configurations.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142184920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Dongsheng Wei, Ming Chen, Chunlin Zhang, Xingang Ai, Zhiwen Xie
As materials science continues to advance, the correlation between microstructure and macroscopic properties has garnered growing interest for optimizing and predicting material performance under various operating conditions. The phase-field method has emerged as a crucial tool for investigating the interplay between microstructural characteristics and internal material properties. In this study, we propose a phase-field approach to couple two-phase growth with stress–strain elastic energy at the mesoscale, enabling the simulation of local stress effects on the solidified structure during the plasma cladding of WC particles and nickel-based alloys. This model offers a more precise prediction of microstructural evolution influenced by stress. Initially, the phase field of WC-Ni binary alloys was modeled, followed by simulations of actual local stress conditions and their impacts on WC particles and nickel-based alloys with ProCAST and finite element analysis software. The results indicate that increased stress reduces grain boundary migration, decelerates WC particle dissolution and diffusion, and diminishes the formation of reaction layers and Ostwald ripening. Furthermore, experimental validation corroborated that the model’s predictions were consistent with the observed microstructural evolution of WC particles and nickel-based alloy composites.
{"title":"Simulation of Localized Stress Impact on Solidification Pattern during Plasma Cladding of WC Particles in Nickel-Based Alloys by Phase-Field Method","authors":"Dongsheng Wei, Ming Chen, Chunlin Zhang, Xingang Ai, Zhiwen Xie","doi":"10.3390/met14091022","DOIUrl":"https://doi.org/10.3390/met14091022","url":null,"abstract":"As materials science continues to advance, the correlation between microstructure and macroscopic properties has garnered growing interest for optimizing and predicting material performance under various operating conditions. The phase-field method has emerged as a crucial tool for investigating the interplay between microstructural characteristics and internal material properties. In this study, we propose a phase-field approach to couple two-phase growth with stress–strain elastic energy at the mesoscale, enabling the simulation of local stress effects on the solidified structure during the plasma cladding of WC particles and nickel-based alloys. This model offers a more precise prediction of microstructural evolution influenced by stress. Initially, the phase field of WC-Ni binary alloys was modeled, followed by simulations of actual local stress conditions and their impacts on WC particles and nickel-based alloys with ProCAST and finite element analysis software. The results indicate that increased stress reduces grain boundary migration, decelerates WC particle dissolution and diffusion, and diminishes the formation of reaction layers and Ostwald ripening. Furthermore, experimental validation corroborated that the model’s predictions were consistent with the observed microstructural evolution of WC particles and nickel-based alloy composites.","PeriodicalId":18461,"journal":{"name":"Metals","volume":null,"pages":null},"PeriodicalIF":2.9,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142184919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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