Pub Date : 2025-01-17DOI: 10.1016/j.ijplas.2025.104247
Xuejian Yang, Mingyang Jiao, Zhijia Liu, Hui Zhao, Yan Peng, Lu Wu, Yu Wu, Rongjian Pan, Baodong Shi
During practical forming processing, strong anisotropic mechanical behavior of dual phase (DP) steels is usually detected due to texture, which further determines subsequent processing optimization with loading paths changing. In order to clarify the underlying deformation mechanisms of DP steels under multi-axial loading, the mechanical response of DP780 under different biaxial loading paths was examined in detail. More precisely, anisotropic behavior of DP780 in complete “σxx-σyy” space was investigated through mechanical testing, microstructure characterization, and crystal plasticity computation based on dislocation density. In particular, biaxial compression test of thin plate is realized by using specifically designed fixture, and consequently yield loci in complete “σxx-σyy” space is detected experimentally. It is found that stronger anisotropy is observed under biaxial loading compared with that under uniaxial loading at macro scale, and biaxial Bauschinger effect is detected with biaxial preloading. At the micro scale, the texture evolution is affected directly by loading paths, and the compression load contributes more to the texture evolution. The distribution of the Taylor Factor under different biaxial loading paths reveals the impact of tension and compression on the main activated slip systems (MASS). Under biaxial tension and biaxial compression loading, the MASS of DP780 is the {112} slip system. Under combined biaxial tension and compression loading, the MASS is the {110} slip system. Using crystal plasticity, the evolution of dislocation density under different biaxial loading is captured. The relationship between the biaxial Bauschinger effect and MASS is clarified. It is found that the dislocation multiplication of the {112} slip system is more affected by changes in loading path than the {110} slip system. And during the subsequent loading process, the {110} slip system transform to {112} by preloading. Additionally, the relationship between the alteration of the MASS and the evolution of texture, as well as the resulting macroscopic anisotropic behavior has been elucidated.
{"title":"Mechanical responses and microstructure evolution of DP780 in complete σxx-σyy space: experiments and crystal plasticity characterization","authors":"Xuejian Yang, Mingyang Jiao, Zhijia Liu, Hui Zhao, Yan Peng, Lu Wu, Yu Wu, Rongjian Pan, Baodong Shi","doi":"10.1016/j.ijplas.2025.104247","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104247","url":null,"abstract":"During practical forming processing, strong anisotropic mechanical behavior of dual phase (DP) steels is usually detected due to texture, which further determines subsequent processing optimization with loading paths changing. In order to clarify the underlying deformation mechanisms of DP steels under multi-axial loading, the mechanical response of DP780 under different biaxial loading paths was examined in detail. More precisely, anisotropic behavior of DP780 in complete “σ<sub>xx</sub>-σ<sub>yy</sub>” space was investigated through mechanical testing, microstructure characterization, and crystal plasticity computation based on dislocation density. In particular, biaxial compression test of thin plate is realized by using specifically designed fixture, and consequently yield loci in complete “σ<sub>xx</sub>-σ<sub>yy</sub>” space is detected experimentally. It is found that stronger anisotropy is observed under biaxial loading compared with that under uniaxial loading at macro scale, and biaxial Bauschinger effect is detected with biaxial preloading. At the micro scale, the texture evolution is affected directly by loading paths, and the compression load contributes more to the texture evolution. The distribution of the Taylor Factor under different biaxial loading paths reveals the impact of tension and compression on the main activated slip systems (MASS). Under biaxial tension and biaxial compression loading, the MASS of DP780 is the {112} slip system. Under combined biaxial tension and compression loading, the MASS is the {110} slip system. Using crystal plasticity, the evolution of dislocation density under different biaxial loading is captured. The relationship between the biaxial Bauschinger effect and MASS is clarified. It is found that the dislocation multiplication of the {112} slip system is more affected by changes in loading path than the {110} slip system. And during the subsequent loading process, the {110} slip system transform to {112} by preloading. Additionally, the relationship between the alteration of the MASS and the evolution of texture, as well as the resulting macroscopic anisotropic behavior has been elucidated.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"12 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.1016/j.ijplas.2025.104248
Shiqi Guo, Siliang Yan, Liang Huang, Kezhuo Liu, Changmin Li
Primary hot working, represented by multi-directional hot forging and annealing, is a crucial step in microstructure control and plays a decisive role in the ultimate performance of ultra-high strength titanium alloy components. However, the interaction mechanisms of multiple physical processes comprising work hardening, dynamic recovery, dynamic recrystallization and grain fragmentation under complex thermo-mechanical routes are not yet well known, which greatly limits the process optimization and control of primary hot working process. In order to accurately predict the macro-micro behaviors of coarse-grained titanium alloys during multi-directional hot deformation and annealing processes, a strain-path dependent unified constitutive model was established comprehensively considering the intragranular coarse grain subdivision (ICGS) caused by ribbon and transgranular subdivided continuous dynamic recrystallization (CDRX), as well as the boundary-based coarse grain subdivision (BCGS) composed of discontinuous dynamic recrystallization (DDRX) coupled with boundary expand CDRX, and the interaction of various mechanisms under dislocation configuration. Through the combination of large deformation framework and viscoplastic theory, the influence of thermo-mechanical loading path and strain rate on grain refinement efficiency was elucidated. In the present model, the cumulative effects of loading direction changes on the degree of grain fragmentation were well identified by defining a new geometric parameter, viz. the loading axis rotation angle of the passes. The ICGS mechanism was introduced to the grain evolution model for the first time, by establishing a quatitative correlation between shear strain and the volume fraction of grain internal subdivision. In this way, the through-process precision prediction of the refinement degree of characteristic regions under multi-directional deformation paths was finally realized by combining BCGS and ICGS mechanisms, and the evolution of mechanical behaviors and internal variables in the alternating multi-directional hot deformation with heat preservation were simulated. The predictive results of the model were consistent with experiments of the titanium alloy with an average error of 4.93% and the refinement degrees of coarse-grained structures under different strain rates, temperatures and cumulative multi-directional large strains were well captured. Moreover, the applicable grain size range of the present constitutive model within a wide strain range was extended to 4 orders of magnitude (from micrometer to centimeter), and the effectiveness of the model in identifying complex multi-directional loading, multiple annealing and the heredity of internal variables during primary hot deformation were validated.
{"title":"A strain-path dependent unified constitutive model of titanium alloy coupling coarse grain subdivision and recrystallization: application to multi-directional hot deformation","authors":"Shiqi Guo, Siliang Yan, Liang Huang, Kezhuo Liu, Changmin Li","doi":"10.1016/j.ijplas.2025.104248","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104248","url":null,"abstract":"Primary hot working, represented by multi-directional hot forging and annealing, is a crucial step in microstructure control and plays a decisive role in the ultimate performance of ultra-high strength titanium alloy components. However, the interaction mechanisms of multiple physical processes comprising work hardening, dynamic recovery, dynamic recrystallization and grain fragmentation under complex thermo-mechanical routes are not yet well known, which greatly limits the process optimization and control of primary hot working process. In order to accurately predict the macro-micro behaviors of coarse-grained titanium alloys during multi-directional hot deformation and annealing processes, a strain-path dependent unified constitutive model was established comprehensively considering the intragranular coarse grain subdivision (ICGS) caused by ribbon and transgranular subdivided continuous dynamic recrystallization (CDRX), as well as the boundary-based coarse grain subdivision (BCGS) composed of discontinuous dynamic recrystallization (DDRX) coupled with boundary expand CDRX, and the interaction of various mechanisms under dislocation configuration. Through the combination of large deformation framework and viscoplastic theory, the influence of thermo-mechanical loading path and strain rate on grain refinement efficiency was elucidated. In the present model, the cumulative effects of loading direction changes on the degree of grain fragmentation were well identified by defining a new geometric parameter, viz. the loading axis rotation angle of the passes. The ICGS mechanism was introduced to the grain evolution model for the first time, by establishing a quatitative correlation between shear strain and the volume fraction of grain internal subdivision. In this way, the through-process precision prediction of the refinement degree of characteristic regions under multi-directional deformation paths was finally realized by combining BCGS and ICGS mechanisms, and the evolution of mechanical behaviors and internal variables in the alternating multi-directional hot deformation with heat preservation were simulated. The predictive results of the model were consistent with experiments of the titanium alloy with an average error of 4.93% and the refinement degrees of coarse-grained structures under different strain rates, temperatures and cumulative multi-directional large strains were well captured. Moreover, the applicable grain size range of the present constitutive model within a wide strain range was extended to 4 orders of magnitude (from micrometer to centimeter), and the effectiveness of the model in identifying complex multi-directional loading, multiple annealing and the heredity of internal variables during primary hot deformation were validated.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"57 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142988057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-13DOI: 10.1016/j.ijplas.2025.104245
Xianbing Zhang, Shubin Wang, Jie Wang, Xinyu Xu, Song Lu, Binbin He
Refractory high-entropy alloys (RHEAs) and medium-entropy alloys (RMEAs) are potential candidates for high-temperature applications; dislocations play crucial roles in the plastic deformation of these alloys at both room and elevated temperatures. However, there is a significant deficiency in the understanding of their temperature-dependent microstructure-mechanical property correlations at low temperatures, which is crucial for evaluating their performance and ensuring service safety under variable-temperature conditions. This study investigated the mechanical properties and deformation mechanisms of a non-equiatomic Ti48.9Zr32.0Nb12.6Ta6.5 RMEA at ambient and cryogenic temperatures. Tensile testing revealed intriguing temperature-dependent behaviors: as the temperature decreased, yield strength increased, while uniform elongation (UE) followed an abnormal U-shaped trend. The RMEA exhibited good UE at 293 K (10.9%), but UE dropped sharply to 185 K (2.2%). However, UE peaked at 77 K (17.2%) along with the highest ultimate tensile strength. These indicated a transition in the deformation mechanisms. Microstructural analysis showed that considerable strain hardening at 293 K was owing to abundant dislocation interactions as well as {112}<111> twins. At 185 K, strain hardening weakened due to suppressed dislocation activity, whereas kinking prevented the ductile-to-brittle transition despite limited UE. The strong strain hardening and enhanced UE at 77 K were attributed to the twinning-induced plasticity effect from {332}<113> deformation twins. In conclusion, this study highlights the anomalous temperature-dependent mechanical behavior of this RMEA and the corresponding evolution of deformation mechanisms. The findings provide key insights into the alloy design and optimizing the performance of RHEAs/RMEAs for applications in cryogenic and variable-temperature environments.
{"title":"Unique transitions in uniform elongation and deformation mechanisms of a refractory medium-entropy alloy at cryogenic temperatures","authors":"Xianbing Zhang, Shubin Wang, Jie Wang, Xinyu Xu, Song Lu, Binbin He","doi":"10.1016/j.ijplas.2025.104245","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104245","url":null,"abstract":"Refractory high-entropy alloys (RHEAs) and medium-entropy alloys (RMEAs) are potential candidates for high-temperature applications; dislocations play crucial roles in the plastic deformation of these alloys at both room and elevated temperatures. However, there is a significant deficiency in the understanding of their temperature-dependent microstructure-mechanical property correlations at low temperatures, which is crucial for evaluating their performance and ensuring service safety under variable-temperature conditions. This study investigated the mechanical properties and deformation mechanisms of a non-equiatomic Ti<sub>48.9</sub>Zr<sub>32.0</sub>Nb<sub>12.6</sub>Ta<sub>6.5</sub> RMEA at ambient and cryogenic temperatures. Tensile testing revealed intriguing temperature-dependent behaviors: as the temperature decreased, yield strength increased, while uniform elongation (<em>UE</em>) followed an abnormal U-shaped trend. The RMEA exhibited good <em>UE</em> at 293 K (10.9%), but <em>UE</em> dropped sharply to 185 K (2.2%). However, <em>UE</em> peaked at 77 K (17.2%) along with the highest ultimate tensile strength. These indicated a transition in the deformation mechanisms. Microstructural analysis showed that considerable strain hardening at 293 K was owing to abundant dislocation interactions as well as {112}<111> twins. At 185 K, strain hardening weakened due to suppressed dislocation activity, whereas kinking prevented the ductile-to-brittle transition despite limited <em>UE</em>. The strong strain hardening and enhanced <em>UE</em> at 77 K were attributed to the twinning-induced plasticity effect from {332}<113> deformation twins. In conclusion, this study highlights the anomalous temperature-dependent mechanical behavior of this RMEA and the corresponding evolution of deformation mechanisms. The findings provide key insights into the alloy design and optimizing the performance of RHEAs/RMEAs for applications in cryogenic and variable-temperature environments.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"6 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142968449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-09DOI: 10.1016/j.ijplas.2025.104244
Zijian Zhang, Lin Yuan, Jiaping Ma, Mingyi Zheng, Debin Shan, Bin Guo
Stress-induced grain boundary (GB) migration plays a crucial role in plastic deformation, influencing the microstructure and mechanical properties of polycrystalline materials. While twinning and grain rotation are important deformation modes, their impact on the GB migration of Mg alloys remains unclear. This work builds the internal relationship between deformation twins, grain rotation, and stress-induced GB migration in a deformed Mg alloy by experiments and simulations. During the uniaxial compression experiment, the GB migration mainly occurs during the tension twin thickening. Atomic simulations reveal that twin thickening results from the slip of interface dislocations along the basal plane (0001) under shear stress. When interface dislocations of twins are hindered by the GB, local stress concentrations lead to GB migration. A new factor I, derived from experimental results, serves as a criterion to differentiate migrated from non-migrated regions during twin thickening at the mesoscale. Grain rotation accompanied by GB migration occurs under mesoscale observations. The scalar disclinations density increases at the GB junctions due to rotation and the disclinations move with the GB migration. Local rotation associated with the formation of low-angle GBs accelerates local migration and contributes to GB serration. Crystal plasticity finite element simulations show that the additional shear stress caused by grain rotation promotes GB migration. Our findings help to understand the GB migration mechanisms of Mg alloys related to the application of Mg alloys through GB engineering.
{"title":"Understanding the stress-induced grain boundary migration behavior in a deformed Mg alloy: the role of deformation twin and grain rotation","authors":"Zijian Zhang, Lin Yuan, Jiaping Ma, Mingyi Zheng, Debin Shan, Bin Guo","doi":"10.1016/j.ijplas.2025.104244","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104244","url":null,"abstract":"Stress-induced grain boundary (GB) migration plays a crucial role in plastic deformation, influencing the microstructure and mechanical properties of polycrystalline materials. While twinning and grain rotation are important deformation modes, their impact on the GB migration of Mg alloys remains unclear. This work builds the internal relationship between deformation twins, grain rotation, and stress-induced GB migration in a deformed Mg alloy by experiments and simulations. During the uniaxial compression experiment, the GB migration mainly occurs during the <span><math><mrow is=\"true\"><mo is=\"true\">{</mo><mrow is=\"true\"><mn is=\"true\">10</mn><mover accent=\"true\" is=\"true\"><mn is=\"true\">1</mn><mo is=\"true\">¯</mo></mover><mn is=\"true\">2</mn></mrow><mo is=\"true\">}</mo></mrow></math></span>tension twin thickening. Atomic simulations reveal that twin thickening results from the slip of interface dislocations along the basal plane (0001) under shear stress. When interface dislocations of twins are hindered by the GB, local stress concentrations lead to GB migration. A new factor <em>I</em>, derived from experimental results, serves as a criterion to differentiate migrated from non-migrated regions during twin thickening at the mesoscale. Grain rotation accompanied by GB migration occurs under mesoscale observations. The scalar disclinations density increases at the GB junctions due to rotation and the disclinations move with the GB migration. Local rotation associated with the formation of low-angle GBs accelerates local migration and contributes to GB serration. Crystal plasticity finite element simulations show that the additional shear stress caused by grain rotation promotes GB migration. Our findings help to understand the GB migration mechanisms of Mg alloys related to the application of Mg alloys through GB engineering.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"67 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Face-centered cubic (FCC) structured FeNiCoCr high-entropy alloys (HEAs) generally demonstrate good plasticity but exhibit relatively low strength. To tackle this challenge, we suggest the following approaches: (1) enhancing work-hardening ability through reducing the stacking fault energy of the alloy system. (2) adjusting the composition of alloying elements to control the formation of precipitation phase, thus fortifying the matrix. Based on the aforementioned perspectives, a series of alloys Fe2NiCoCr(VN)x (x=0, 0.3, 0.5, 1.0) was designed by adjusting the Fe element content in FeNiCoCr HEAs, and then adding V and N alloying elements to the alloy. Experimental results show that Fe2NiCoCr(VN)0.5 HEAs exhibit high-quality work-hardening ability and strength. The yield strength enhanced from 150 MPa to 250 MPa, while the ultimate tensile strength was enhanced from 540 MPa to 800 MPa. This represents an increase of 66% in yield strength and 48% in ultimate tensile strength, respectively. And plasticity remained stable at 25%, outperforming most as-cast FCC-structured HEAs. The changes in stacking fault energy and the dislocation slip behaviors around the precipitation phase were also calculated by the Molecular Dynamics simulation software Large-scale Atomic/Molecular Massively Parallel Simulator. This study not only reduces costs but also provides insights into the tunability of the mechanical properties of materials through alloying non-equiatomic HEAs.
{"title":"Improvement of work-hardening capability and strength of FeNiCoCr-based high-entropy alloys by modulation of stacking fault energy and precipitation phase","authors":"Lei Zhang, Zhiyu Feng, Zixian Xiong, Xinlong Zhang, Bingzhao Wu, Chunyu Zhao","doi":"10.1016/j.ijplas.2025.104242","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104242","url":null,"abstract":"Face-centered cubic (FCC) structured FeNiCoCr high-entropy alloys (HEAs) generally demonstrate good plasticity but exhibit relatively low strength. To tackle this challenge, we suggest the following approaches: (1) enhancing work-hardening ability through reducing the stacking fault energy of the alloy system. (2) adjusting the composition of alloying elements to control the formation of precipitation phase, thus fortifying the matrix. Based on the aforementioned perspectives, a series of alloys Fe<sub>2</sub>NiCoCr(VN)<sub>x</sub> (x=0, 0.3, 0.5, 1.0) was designed by adjusting the Fe element content in FeNiCoCr HEAs, and then adding V and N alloying elements to the alloy. Experimental results show that Fe<sub>2</sub>NiCoCr(VN)<sub>0.5</sub> HEAs exhibit high-quality work-hardening ability and strength. The yield strength enhanced from 150 MPa to 250 MPa, while the ultimate tensile strength was enhanced from 540 MPa to 800 MPa. This represents an increase of 66% in yield strength and 48% in ultimate tensile strength, respectively. And plasticity remained stable at 25%, outperforming most as-cast FCC-structured HEAs. The changes in stacking fault energy and the dislocation slip behaviors around the precipitation phase were also calculated by the Molecular Dynamics simulation software Large-scale Atomic/Molecular Massively Parallel Simulator. This study not only reduces costs but also provides insights into the tunability of the mechanical properties of materials through alloying non-equiatomic HEAs.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"37 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-08DOI: 10.1016/j.ijplas.2025.104243
Guandong Luo, Han Chen, Lei Hu, Chen Yang, Shuwei Zong, Yanchi Chen, Qing Lian, Hongze Wang, Zhe Chen, Yi Wu, Haowei Wang
Eutectic Al alloys processed by laser powder bed fusion (LPBF) frequently display metastable cellular structures. The cells are susceptible to decomposition into nanoparticles during ageing. Furthermore, supersaturated solutes can result in additional precipitation during the ageing process. The complicated microstructure evolution observed in LPBF eutectic Al alloys necessitates a comprehensive investigation into their ageing behaviour, to identify the optimal strength and plasticity. Consequently, this study presents a systematic examination of the impact of direct ageing on microstructure evolution in an LPBF Al‒Ni‒Sc‒Zr alloy, analysing associated changes in strength and plasticity. The optimal ageing parameters for strength and plasticity are determined. The results demonstrate that the reduction in strength resulting from cell decomposition can be offset by the strengthening provided by nanoparticles formed due to cell wall spheroidisation and additional supersaturated solute precipitation, achieving excellent yield strength. Furthermore, the transformation of cells into nanoparticles significantly enhances the plasticity by increasing non-uniform strain, which is not well explained by the conventional work hardening theory. A detailed investigation suggests that direct ageing can alleviate dislocation pile-up and strain localisation around cell walls, and reduce the tendency for crack propagation along melt pool boundaries, resulting in a significant increase in non-uniform strain and ultimately, excellent tensile plasticity. This study demonstrates that direct ageing is an effective strategy for simultaneously enhancing the strength and plasticity of LPBF Al–Ni based alloys. The proposed plasticity mechanism offers a new insight into the plastic deformation behaviour of LPBF eutectic Al alloys.
{"title":"Simultaneously enhancing strength and plasticity via direct ageing in additive manufactured Al–Ni–Sc–Zr alloys","authors":"Guandong Luo, Han Chen, Lei Hu, Chen Yang, Shuwei Zong, Yanchi Chen, Qing Lian, Hongze Wang, Zhe Chen, Yi Wu, Haowei Wang","doi":"10.1016/j.ijplas.2025.104243","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104243","url":null,"abstract":"Eutectic Al alloys processed by laser powder bed fusion (LPBF) frequently display metastable cellular structures. The cells are susceptible to decomposition into nanoparticles during ageing. Furthermore, supersaturated solutes can result in additional precipitation during the ageing process. The complicated microstructure evolution observed in LPBF eutectic Al alloys necessitates a comprehensive investigation into their ageing behaviour, to identify the optimal strength and plasticity. Consequently, this study presents a systematic examination of the impact of direct ageing on microstructure evolution in an LPBF Al‒Ni‒Sc‒Zr alloy, analysing associated changes in strength and plasticity. The optimal ageing parameters for strength and plasticity are determined. The results demonstrate that the reduction in strength resulting from cell decomposition can be offset by the strengthening provided by nanoparticles formed due to cell wall spheroidisation and additional supersaturated solute precipitation, achieving excellent yield strength. Furthermore, the transformation of cells into nanoparticles significantly enhances the plasticity by increasing non-uniform strain, which is not well explained by the conventional work hardening theory. A detailed investigation suggests that direct ageing can alleviate dislocation pile-up and strain localisation around cell walls, and reduce the tendency for crack propagation along melt pool boundaries, resulting in a significant increase in non-uniform strain and ultimately, excellent tensile plasticity. This study demonstrates that direct ageing is an effective strategy for simultaneously enhancing the strength and plasticity of LPBF Al–Ni based alloys. The proposed plasticity mechanism offers a new insight into the plastic deformation behaviour of LPBF eutectic Al alloys.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"37 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937011","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A polycrystalline elastic-plastic phase field model is proposed to reveal the mechanisms of secondary crack initiation, propagation and closure during the water quenching process in medium-carbon martensitic steel. The formation of martensite variants during the quenching process is considered in our model. Moreover, this model can account for the influence of the elastic stress and plastic strain generated after the martensitic transformation during the quenching process on the fracture process. The simulation results show that secondary cracks initiate at the grain boundary region near the primary crack due to its induction. Additionally, they can also initiate at multiple locations in the high-angle grain boundary regions far from the primary crack. This occurs due to elastic stress concentration and plastic strain localization in these regions. Then secondary cracks mainly propagate along prior austenite grain boundary areas. The tensile stress on both sides of the crack tip is the main driving force for crack initiation and propagation. As the external loading increases, the stress at the crack tip gradually transitions into compressive stress, ultimately leading to the closure of the crack in the grain boundary regions. More importantly, these propagation paths of secondary cracks are consistent with the experimental results. Compared with intracrystalline defects, grain boundary defects are more likely to induce crack initiation and propagation. Therefore, this model can offer theoretical guidance for solving the issue of water quenching cracking in medium-carbon martensitic steel.
{"title":"Mechanisms of secondary crack initiation and propagation and closure during the water quenching process in medium-carbon martensitic steel","authors":"Hongqing Zheng, Yuchen Yang, Jie Li, Xunwei Zuo, Jianfeng Wan, Yonghua Rong, Nailu Chen","doi":"10.1016/j.ijplas.2025.104240","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104240","url":null,"abstract":"A polycrystalline elastic-plastic phase field model is proposed to reveal the mechanisms of secondary crack initiation, propagation and closure during the water quenching process in medium-carbon martensitic steel. The formation of martensite variants during the quenching process is considered in our model. Moreover, this model can account for the influence of the elastic stress and plastic strain generated after the martensitic transformation during the quenching process on the fracture process. The simulation results show that secondary cracks initiate at the grain boundary region near the primary crack due to its induction. Additionally, they can also initiate at multiple locations in the high-angle grain boundary regions far from the primary crack. This occurs due to elastic stress concentration and plastic strain localization in these regions. Then secondary cracks mainly propagate along prior austenite grain boundary areas. The tensile stress on both sides of the crack tip is the main driving force for crack initiation and propagation. As the external loading increases, the stress at the crack tip gradually transitions into compressive stress, ultimately leading to the closure of the crack in the grain boundary regions. More importantly, these propagation paths of secondary cracks are consistent with the experimental results. Compared with intracrystalline defects, grain boundary defects are more likely to induce crack initiation and propagation. Therefore, this model can offer theoretical guidance for solving the issue of water quenching cracking in medium-carbon martensitic steel.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"76 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142935215","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
During the deformation of body-centered cubic (BCC) structured lightweight refractory high-entropy alloys (LRHEAs), strain localization caused by a low strain-hardening rate (SHR) induces premature alloy necking, resulting in poor uniform tensile ductility (UTD) and restricts their processability and applicability. In this study, we improved the SHR of the alloys from negative to 1.5 GPa by tailoring multi-scale heterostructures, including the microscopic bimodal grain distribution, submicron spherical C14 Laves phase, nanoscale local chemical fluctuations (LCFs), and atomic clusters less than 1nm. The strength of the alloy was raised by 13.8%, and the UTD increased by 710% compared with the initial homogenized sample, and overall performance was superior to most LRHEAs. Bimodal grain interfaces can effectively coordinate the strain distribution between the two during deformation, accelerating the generation and storage of geometrically necessary dislocations (GNDs), and the back stress accumulates and increases with strain, stabilizing the hardening ability. Meanwhile, the meticulously dispersed C14 Laves phase plays a role in precipitation strengthening without compromising plasticity. The matrix's LCFs and Al-Zr atomic clusters can further regulate the morphology and distribution of statistically stored dislocations (SSDs). On the one hand, they could effectively pin dislocations and cause them to bend, increasing the migration resistance of SSDs; on the other hand, dislocation tangles resulting from microbands blocking and the interaction of multi-slip systems activate new dislocation sources, which lead to the rapid expansion of secondary microbands in a reticular manner. Those significantly increase the synchronous dislocation multiplication rate and dynamic dislocation density during plastic deformation, maintaining high and sustained SHR of alloys. Therefore, the SHR of LRHEA can be effectively improved by introducing multi-scale heterogeneous structures to optimize the coordination of GND and SSD density and distribution, thus achieving an excellent match between strength and UTD.
{"title":"Enhancing the strain-hardening rate and uniform tensile ductility of lightweight refractory high-entropy alloys by tailoring multi-scale heterostructure strategy","authors":"Yansong Zhang, Huaming Wang, Junwei Yang, Yanyan Zhu, Jia Li, Zhuo Li, Bing Su, Bingsen Liu, Chunjie Shen","doi":"10.1016/j.ijplas.2024.104237","DOIUrl":"https://doi.org/10.1016/j.ijplas.2024.104237","url":null,"abstract":"During the deformation of body-centered cubic (BCC) structured lightweight refractory high-entropy alloys (LRHEAs), strain localization caused by a low strain-hardening rate (SHR) induces premature alloy necking, resulting in poor uniform tensile ductility (UTD) and restricts their processability and applicability. In this study, we improved the SHR of the alloys from negative to 1.5 GPa by tailoring multi-scale heterostructures, including the microscopic bimodal grain distribution, submicron spherical C14 Laves phase, nanoscale local chemical fluctuations (LCFs), and atomic clusters less than 1nm. The strength of the alloy was raised by 13.8%, and the UTD increased by 710% compared with the initial homogenized sample, and overall performance was superior to most LRHEAs. Bimodal grain interfaces can effectively coordinate the strain distribution between the two during deformation, accelerating the generation and storage of geometrically necessary dislocations (GNDs), and the back stress accumulates and increases with strain, stabilizing the hardening ability. Meanwhile, the meticulously dispersed C14 Laves phase plays a role in precipitation strengthening without compromising plasticity. The matrix's LCFs and Al-Zr atomic clusters can further regulate the morphology and distribution of statistically stored dislocations (SSDs). On the one hand, they could effectively pin dislocations and cause them to bend, increasing the migration resistance of SSDs; on the other hand, dislocation tangles resulting from microbands blocking and the interaction of multi-slip systems activate new dislocation sources, which lead to the rapid expansion of secondary microbands in a reticular manner. Those significantly increase the synchronous dislocation multiplication rate and dynamic dislocation density during plastic deformation, maintaining high and sustained SHR of alloys. Therefore, the SHR of LRHEA can be effectively improved by introducing multi-scale heterogeneous structures to optimize the coordination of GND and SSD density and distribution, thus achieving an excellent match between strength and UTD.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"2 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142925143","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-04DOI: 10.1016/j.ijplas.2025.104241
Zhide Li, Cheng Lu, Charlie Kong, M.W. Fu, Hailiang Yu
High strength and good ductility are essential for the engineering applications of structural materials, yet these two attributes often do not coexist. In the present study, a composite heterostructuring designed with multi-scale, lamellar, and bimodal was developed to deal with the trade-off between strength and ductility. This heterostructuring includes coarse-grain soft domains arranged in a lamellar structure within a matrix characterized by both fine and ultrafine grains arranged in a bimodal structure created through a straightforward thermo-mechanical process. The gradient in strength among various grain structures generates a gradient in strain during deformation. This promotes the generation of additional geometrically necessary dislocations (GNDs) in the soft domain, favouring strength enhancement. The ongoing and efficient accumulation and evolution of GNDs within the soft domains are further developed into the dislocation cells and subgrain boundaries, which, on the other hand, increase the strain hardening and, hence, the ductility.
{"title":"Enhancing the strength and ductility of pure metal via multi-scale and multitype composite heterostructuring","authors":"Zhide Li, Cheng Lu, Charlie Kong, M.W. Fu, Hailiang Yu","doi":"10.1016/j.ijplas.2025.104241","DOIUrl":"https://doi.org/10.1016/j.ijplas.2025.104241","url":null,"abstract":"High strength and good ductility are essential for the engineering applications of structural materials, yet these two attributes often do not coexist. In the present study, a composite heterostructuring designed with multi-scale, lamellar, and bimodal was developed to deal with the trade-off between strength and ductility. This heterostructuring includes coarse-grain soft domains arranged in a lamellar structure within a matrix characterized by both fine and ultrafine grains arranged in a bimodal structure created through a straightforward thermo-mechanical process. The gradient in strength among various grain structures generates a gradient in strain during deformation. This promotes the generation of additional geometrically necessary dislocations (GNDs) in the soft domain, favouring strength enhancement. The ongoing and efficient accumulation and evolution of GNDs within the soft domains are further developed into the dislocation cells and subgrain boundaries, which, on the other hand, increase the strain hardening and, hence, the ductility.","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"32 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142924679","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-02DOI: 10.1016/j.ijplas.2024.104228
Namit Pai, Indradev Samajdar, Anirban Patra
This work presents a combined experimental and crystal plasticity finite element modeling study on the development of bulk and local residual strains during tensile and cyclic deformation of an austenitic stainless steel. The <span><math><mrow is="true"><mo is="true">(</mo><mi is="true">h</mi><mi is="true">k</mi><mi is="true">l</mi><mo is="true">)</mo></mrow></math></span>-specific bulk (residual) lattice strains are measured using X-ray Diffraction, while the local residual strains are measured using High Resolution Electron Back Scatter Diffraction. The residual strains are predicted using a dislocation density-based crystal plasticity model, with consideration for directional hardening due to backstress evolution. The work emphasizes on residual strain developments for four specific grain families: <span><math><mrow is="true"><mo is="true">(</mo><mn is="true">111</mn><mo is="true">)</mo></mrow></math></span>, <span><math><mrow is="true"><mo is="true">(</mo><mn is="true">001</mn><mo is="true">)</mo></mrow></math></span>, <span><math><mrow is="true"><mo is="true">(</mo><mn is="true">101</mn><mo is="true">)</mo></mrow></math></span> and <span><math><mrow is="true"><mo is="true">(</mo><mn is="true">311</mn><mo is="true">)</mo></mrow></math></span>, specifically in terms of their correlation with the underlying microstructure, studied using crystallographic orientation, misorientation, dislocation density and backstress evolution. Large intragranular orientation gradients, dislocation densities and backstress are observed during tensile deformation for the texturally dominant <span><math><mrow is="true"><mo is="true">(</mo><mn is="true">101</mn><mo is="true">)</mo></mrow></math></span> grain family, indicating that these grains have higher plastic deformation as compared to the <span><math><mrow is="true"><mo is="true">(</mo><mn is="true">001</mn><mo is="true">)</mo></mrow></math></span> and <span><math><mrow is="true"><mo is="true">(</mo><mn is="true">111</mn><mo is="true">)</mo></mrow></math></span> grain families. This also contributes to the observed relaxation in lattice strains for the <span><math><mrow is="true"><mo is="true">(</mo><mn is="true">101</mn><mo is="true">)</mo></mrow></math></span> grain family, with the resulting load shed being primarily accommodated by the <span><math><mrow is="true"><mo is="true">(</mo><mn is="true">001</mn><mo is="true">)</mo></mrow></math></span> grain family. In contrast, no such orientation gradients or lattice strain relaxations are observed in the cyclically deformed material. The measured local residual strains, which are also qualitatively predicted by the crystal plasticity simulations, highlight the additional effect of spatial heterogeneity and neighboring grains on the development of residual strains. Finally, statistical analysis of the simulated residual strains reveals that the hierarchy in the development of lattice strains is in the following order for the different grain families: <span><ma
{"title":"Study of orientation-dependent residual strains during tensile and cyclic deformation of an austenitic stainless steel","authors":"Namit Pai, Indradev Samajdar, Anirban Patra","doi":"10.1016/j.ijplas.2024.104228","DOIUrl":"https://doi.org/10.1016/j.ijplas.2024.104228","url":null,"abstract":"This work presents a combined experimental and crystal plasticity finite element modeling study on the development of bulk and local residual strains during tensile and cyclic deformation of an austenitic stainless steel. The <span><math><mrow is=\"true\"><mo is=\"true\">(</mo><mi is=\"true\">h</mi><mi is=\"true\">k</mi><mi is=\"true\">l</mi><mo is=\"true\">)</mo></mrow></math></span>-specific bulk (residual) lattice strains are measured using X-ray Diffraction, while the local residual strains are measured using High Resolution Electron Back Scatter Diffraction. The residual strains are predicted using a dislocation density-based crystal plasticity model, with consideration for directional hardening due to backstress evolution. The work emphasizes on residual strain developments for four specific grain families: <span><math><mrow is=\"true\"><mo is=\"true\">(</mo><mn is=\"true\">111</mn><mo is=\"true\">)</mo></mrow></math></span>, <span><math><mrow is=\"true\"><mo is=\"true\">(</mo><mn is=\"true\">001</mn><mo is=\"true\">)</mo></mrow></math></span>, <span><math><mrow is=\"true\"><mo is=\"true\">(</mo><mn is=\"true\">101</mn><mo is=\"true\">)</mo></mrow></math></span> and <span><math><mrow is=\"true\"><mo is=\"true\">(</mo><mn is=\"true\">311</mn><mo is=\"true\">)</mo></mrow></math></span>, specifically in terms of their correlation with the underlying microstructure, studied using crystallographic orientation, misorientation, dislocation density and backstress evolution. Large intragranular orientation gradients, dislocation densities and backstress are observed during tensile deformation for the texturally dominant <span><math><mrow is=\"true\"><mo is=\"true\">(</mo><mn is=\"true\">101</mn><mo is=\"true\">)</mo></mrow></math></span> grain family, indicating that these grains have higher plastic deformation as compared to the <span><math><mrow is=\"true\"><mo is=\"true\">(</mo><mn is=\"true\">001</mn><mo is=\"true\">)</mo></mrow></math></span> and <span><math><mrow is=\"true\"><mo is=\"true\">(</mo><mn is=\"true\">111</mn><mo is=\"true\">)</mo></mrow></math></span> grain families. This also contributes to the observed relaxation in lattice strains for the <span><math><mrow is=\"true\"><mo is=\"true\">(</mo><mn is=\"true\">101</mn><mo is=\"true\">)</mo></mrow></math></span> grain family, with the resulting load shed being primarily accommodated by the <span><math><mrow is=\"true\"><mo is=\"true\">(</mo><mn is=\"true\">001</mn><mo is=\"true\">)</mo></mrow></math></span> grain family. In contrast, no such orientation gradients or lattice strain relaxations are observed in the cyclically deformed material. The measured local residual strains, which are also qualitatively predicted by the crystal plasticity simulations, highlight the additional effect of spatial heterogeneity and neighboring grains on the development of residual strains. Finally, statistical analysis of the simulated residual strains reveals that the hierarchy in the development of lattice strains is in the following order for the different grain families: <span><ma","PeriodicalId":340,"journal":{"name":"International Journal of Plasticity","volume":"14 1","pages":""},"PeriodicalIF":9.8,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142911523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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