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An iterative blending integrating grinding force model considering grain size and dislocation density evolution

Advances in Manufacturing 2023年第3期11卷 428-443页

作者： Zi-Shan Ding Yun-Hui Zhao Miao-Xian Guo Wei-Cheng Guo Chong-Jun Wu Steven Y.Liang School of Mechanical Engineering University of Shanghai for Science and TechnologyShanghai 200093People's Republicof China College of Mechanical Engineering Donghua UniversityShanghai 201620People's Republic of China George W.Woodruff School of Mechanical Engineering Georgia Institute of TechnologyAtlanta 30332USA

The dynamic force load in grinding process is considered as a crucial factor affecting the quality of parts,and a better understanding of the mechanism of force generation is conducive to revealing the evolution of material microstructure more precisely.In this study,an iterative blending integrating grinding force model that comprehensively considers the impact of grain size and dislocation density evolution of the material is proposed.According to the grinding kinematics,the interaction of grit-workpiece is divided into rubbing,plowing,and chip formation stages in each grinding zone.On this basis,the evolution of material microstructure in the current chip formation stage will affect the rubbing force in the next grinding arc through flow stresses,which in turn will influence the total grinding force.Therefore,the flow stress models in rubbing and chip formation stages are firstly established,and then the dislocation density prediction model is established experimentally based on the characteristics of grain size.The effects of the evolution of grain size and dislocation density on the grinding forces during the grinding process are studied by means of iterative cycles.The results indicate that the implementation of an iterative blending scheme is instrumental in obtaining a higher accurate prediction of the grinding force and a deeper insight of the influence mechanisms of materials microstructure on grinding process.

关键词： Grinding force Grain size dislocation density Iterative loop

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Mechanism of high-energy pulsed current-assisted rolling of 08AL carbon steel ultra-thin strip

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Journal of Iron and Steel Research(International) 2024年第2期31卷 416-427页

作者： Zhong-kai Ren Ya-nan Xu Jia-zhao Chen He Li Rui-lin Yuan Zhen-hua Wang Tao Wang Xiao Liu College of Mechanical and Vehicle Engineering Taiyuan University of TechnologyTaiyuan030024ShanxiChina Engineering Research Center of Advanced Metal Composites Forming Technology and Equipment(Ministry of Education) Taiyuan University of TechnologyTaiyuan030024ShanxiChina National Key Laboratory of Metal Forming Technology and Heavy Equipment China National Heavy Machinery Research Institute Co.Ltd.Xi’an710016ShaanxiChina

To improve the plastic deformation performance of a 08AL carbon steel ultra-thin strip,a pulsed electric field was integrated into the plastic processing of the ultra-thin strip,and the effects of high-energy current on its deformation ability were investigated.Current-assisted tensile tests were employed,and the results clarified that the pulsed current could reduce the activation energy of faults and promoted dislocation slip within grains and at grain boundaries,leading to a decrease in the deformation resistance of the metal and an increase in its plastic properties.Under the current density of 2.0 A/mm2,the yield strength,tensile strength,and elongation of the rolled sample reached 425 MPa,467 MPa,and 12.5%,respectively.During the rolling process,it was found that the pulsed current promoted the dynamic recrystallization of the ultra-thin strip,reduced its dislocation density and deformation resistance,and promoted the coordinated deformation of the metal.

关键词： 08AL ultra-thin strip High-energy pulsed current Mechanical property dislocation density Dynamic recrystallization

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In-situ study of the microstructure evolution during tension of a Mg-Y-Zn-Al alloy processed by rapidly solidified ribbon consolidation technique

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Journal of Magnesium and Alloys 2024年第5期12卷 2024-2040页

作者： Jen? Gubicza Kristián Máthis Péter Nagy Péter Jenei Zoltán Heged?s Andrea Farkas Jozef Vesely Shin-ichi Inoue Daria Drozdenko Yoshihito Kawamura Department of Materials Physics Faculty of Science E?tv?s Loránd University Department of Physics of Materials Faculty of Mathematics and Physics Charles University Deutsches Elektronen-Synchrotron DESY Magnesium Research Center Kumamoto University

Mg-Y-Zn-Al alloys processed by rapidly solidified ribbon consolidation（RSRC） technique exhibit an exceptional mechanical performance indicating promising application potential. This material has a bimodal microstructure consisting of fine recrystallized and coarse non-recrystallized grains with solute-rich stacking faults forming cluster arranged layers（CALs） and nanoplates（CANaPs）, or complete long period stacking ordered（LPSO） phase. In order to reveal the deformation mechanisms, in-situ synchrotron X-ray diffraction line profile analysis was employed for a detailed study of the dislocation arrangement created during tension in Mg-0.9% Zn-2.05% Y-0.15%Al（at%） alloy. For uncovering the effect of the initial microstructure on the mechanical performance, additional samples were obtained by annealing of the as-consolidated specimen at 300 and 400 ℃ for 2 h. The heat treatment at 300 ℃ had no significant effect on the initial microstructure, its evolution during tension and, thus, the overall deformation behavior under tensile loading. On the other hand,annealing at 400 ℃ resulted in a significant increase of the recrystallized grains fraction and a decrease of the dislocation density, leading to only minor degradation of the mechanical strength. The maximum dislocation density at the failure of the samples corresponding to the plastic strain of 10-25% was estimated to be about 16-20 × 1014m-2. The diffraction profile analysis indicated that most dislocations formed during tension were of non-basaland pyramidaltypes, what was also in agreement with the Schmid factor values revealed independently from orientation maps. It was also shown that the dislocation-induced Taylor hardening was much lower below the plastic strain of 3% than above this value, which was explained by a model of the interaction between prismatic dislocations and CANaPs/LPSO plates.

关键词： Mg-Zn-Y-Al alloy Long period stacking ordered (LPSO) phase Cluster arranged nanoplates (CANaPs) Annealing Tension dislocation density Hardening

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The combined influence of grain size distribution and dislocation density on hardness of interstitial free steel

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Journal of Materials Science & Technology 2020年第10期42卷 35-43页

作者： Wei Li Martina Vittorietti Geurt Jongbloed Jilt Sietsma Department of Materials Science and Engineering Delft University of TechnologyMekelweg 22628 CDDelftthe Netherlands Department of Applied Mathematics Delft University of TechnologyVan Mourik Broekmanweg 62628 XEDelftthe Netherlands Materials Innovation Institute(M2i) Van der Burghweg 1.2628 CSDelftthe Netherlands

Understanding the relationship between microstructure features and mechanical properties is of great significance for the improvement and specific adjustment of steel properties.The relationship between mean grain size and yield strength is established by the well-known Hall-Petch equation.But due to the complexity of the grain configuration within materials,considering only the mean value is unlikely to give a complete representation of the mechanical behavior.The classical Taylor equation is often used to account for the effect of dislocation density,but not thoroughly tested in combination with grain size influence.In the present study,systematic heat treatment routes and cold rolling followed by annealing are designed for interstitial free(IF)steel to achieve ferritic microstructures that not only vary in mean grain size,but also in grain size distribution and in dislocation density,a combination that is rarely studied in the literature.Optical microscopy is applied to determine the grain size distribution.The dislocation density is determined through XRD measurements.The hardness is analyzed on its relation with the mean grain size,as well as with the grain size distribution and the dislocation density.With the help of the variable selection tool LASSO,it is shown that dislocation density,mean grain size and kurtosis of grain size distribution are the three features which most strongly affect hardness of IF steel.

关键词： Interstitial free steel Hardness Grain size distribution dislocation density

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Microstructural evolution,dislocation density and tensile properties of Al–6.5Si–2.1Cu–0.35Mg alloy produced by different casting processes

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Journal of Materials Science & Technology 2021年第36期95卷 145-157页

作者： S.Samat M.Z.Omar A.H.Baghdadi I.F.Mohamed A.Rajabi A.M.Aziz Department of Mechanical and Manufacturing Engineering Faculty of Engineering and Built EnvironmentUniversiti Kebangsaan MalaysiaBangiUKM 43600Malaysia

Al–Si–Cu–Mg foundry alloys are used in casting process technologies.However,their strength properties remain low due to their microstructural characteristics and porosity.In this work,the microstructural characteristics,dislocation densities,and mechanical properties of Al–Si–Cu–Mg cast alloys prepared through different casting methods were studied experimentally.Four casting processes,namely,gravity casting(GC),rheocasting(RC),thixoforming(Thixo),and Thixo with heat treatment,were used.The GC and RC samples had mainly dendriticα-Al phase microstructures and exhibited coarse Si particles and intermetallic compounds in their interdendritic regions.By contrast,the Thixo and heat-treated Thixo(HT-Thixo)samples exhibited microstructural refinement with uniformly distributedα-Al globules,fine fibrous Si particles,and fragmented intermetallic compounds amongα-Al globules.The accumulation of dislocation densities increased in the Thixo sample as the strain was increased due to plastic deformation.Furthermore,the ultimate tensile strength and yield strength of the HT-Thixo sample increased by 87%and 63%,respectively,relative to those of the GC sample.The cleavage fracture displayed by the GC and RC samples led to brittle failure.Meanwhile,the Thixo and HT-Thixo samples presented dimple-based ductile fracture.

关键词： Al–Si–Cu–Mg alloy Thixoforming Microstructure Mechanical property dislocation density

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Compositional complexity dependence of dislocation density and mechanical properties in high entropy alloy systems

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Progress in Natural Science:Materials International 2020年第4期30卷 545-551页

作者： P.Thirathipviwat G.Song J.Bednarcik U.Kühn T.Gemming K.Nielsch J.Han Leibniz Institute of Solid State and Materials Research (IFW Dresden) Frontier Research Center for Applied Atomic Sciences Ibaraki University Division of Advanced Materials Engineering and Institute for rare metals Kongju National University Institute of Physic Pavol Jozef Safarik University in Ko?ice Deutsches Elektronen-Synchrotron (DESY) Institute of Materials Science Technische Universit?t Dresden Institute of Applied Physics Technische Universit?t Dresden Korea Institute for Rare Metals Korea Institute of Industrial Technology (KITECH)

This study focuses on a quantitative analysis of dislocation accumulation after cold plastic deformation and mechanical properties of Fe Ni Co Cr Mn and Ti Nb Hf Ta Zr high entropy alloys(HEAs) which are single phase fcc and bcc solid solutions, respectively. In order to study the role of compositional complexity from unary to quinary compositions on dislocation accumulation and mechanical properties after plastic deformation, the single solid solution phase forming sub-alloys of the two HEAs were investigated. All studied samples revealed a large plastic deformability under cold-rotary swaging process by 85–90% area reduction without intermediate annealing. The dislocation density of all studied samples, determined by Williamson-Hall method on synchrotron X-ray diffraction patterns, were between 1014-1015m-2dependent on the alloy composition. The level of dislocation density after plastic deformation is not only affected by the number of constituent element but the lattice distortion and intrinsic properties in terms of stacking fault energy, modulus misfit, and melting point also impact the dislocation storage. The level of dislocation density determines the level of mechanical properties because of a resistance to dislocation motions. The hardness and yield compressive strength of the studied samples are proportional to the level of dislocation density.

关键词： High entropy alloys dislocation density Synchrotron XRD Mechanical properties

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dislocation characteristics and dynamic recrystallization in hot deformed AM30 and AZ31 alloys

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Journal of Magnesium and Alloys 2022年第12期10卷 3495-3505页

作者： Hyeon-Woo Son Soong-Keun Hyun Metallic Materials Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea Department of Materials Science and Engineering Inha UniversityIncheon 22212Republic of Korea

Zn addition to Mg alloys activates non-basal slip or twinning with solute softening effects.On the other hand,the effects of the Zn solute on the macroscopic dislocation behavior and dynamic recrystallization are not completely understood.Moreover,it is unclear ifslip can be affected by changes in the c/a ratio of solute atoms.This study was conducted to understand the solute strengthening of Zn addition and its effects on the dislocation characteristics and dynamic recrystallization.A hot torsion test was performed on both AM30 and AZ31 alloys up to a high strain to investigate the Zn solute effect on the dislocation characteristics and dynamic recrystallization.The dislocation components of the hot torsioned alloys were evaluated by X-ray line profile analysis and electron backscatter diffraction.The results showed that the Zn solutes slightly accelerate strain accumulation at the initial stages of hot deformation,which accelerated recrystallization at high strain.The dislocation characteristics were changed dynamically by Zn addition:fortified-type slip,dislocation arrangement and strain anisotropy parameters.The most important point was that the dislocation characteristics were changed dramatically at the critical strain for recrystallization and high strain regions.The addition of Zn also acted greatly in these strain areas.This indicates that the rapid formation of-type slip at the serrated grain boundaries occurs at the initiation of dynamic recrystallization and the increase in the grain triple junction because grain refinement has a great influence on the dislocation characteristics at high strain.

关键词： Magnesium alloy X-ray line profile Solid solution dislocation density Dynamic recrystallization

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Microstructure, dislocation density and Thermal Expansion Behavior Using Thermo Elastic Models of Zircon Sand Reinforced as Cast ZA-27 Composites

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Journal of Minerals and Materials Characterization and Engineering 2021年第1期9卷 100-115页

作者： G. R. Gurunagendra V. Bharat B. R. Raju D. G. Amith Vijayakumar Pujar C. Ravi Keerthi Global Academy of Technology Bangalore India The Oxford College of Engineering Bangalore India

In the present work stir casting route is used to fabricate the ZA27 Metal matrix composites containing 3 wt%, 6 wt%, 9 wt%, and 12 wt%. Zircon sand particulates of size 100 mesh. Microstructure studies using Optical Microscopy, SEM-EDAX are carried out to ascertain the distribution and morphology of particulates in the composites. Effect of zircon sand as reinforcement on bulk density, porosity, of the fabricated composites is studied. SEM studies are carried out to understand the behavior of as-cast ZA27 alloy reinforced with zircon sand. The dislocation density of the fabricated composite affects the strength of the composites and depends on the strain due to thermal mismatch and is found to increase with increase in weight% of zircon sand. However, it does not consider casting defects of voids/clustering observed in micrographs of the fabricated composite. Porosity in composites does not have influence on Coefficient of thermal expansion (CTE) of the ZA27 composites studied using thermoelastic models like Kerner and turner model and rule of mixtures of composite.

关键词： density Porosity dislocation density Thermoelastic Models Rule of Mixtures

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Deformation and phase transformation mechanisms of 40Cr10Si2Mo steel during hot compression

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Journal of Iron and Steel Research(International) 2023年第4期30卷 760-771页

作者： Qing-juan Wang Qin-ren Wang Zhong-ze Du Ze-en He Xue Dang Ze-jiang Qi Cong-cong Yang School of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an 710055ShaanxiChina

Thermo-mechanical experiments on martensitic heat-resistant 40Cr10Si2Mo steel were conducted using a Gleeble simulator in temperature and strain rate ranges of 1073–1373 K and 0.1–20 s^(-1),respectively.Processing maps were developed and correlated with deformed microstructures based on the dynamic material model theory.The analysis of the maps revealed that both applied temperature and strain rate had significant effects on the power dissipation efficiency and flow instability of the steel alloy.Electron backscatter diffraction analysis was also implemented to study the effect of deformation conditions on martensitic morphology.The results showed that higher temperatures and strain rates led to a fine martensitic packet,and the martensite lath increased in width at high temperatures.Two deformation domains,which exhibit different recrystallization processes,were recognized.The discontinuous dynamic recrystallization(DRX)mechanism in the low strain rate domain was characterized by the migration and growth of high-angle grains during straining.In contrast,in the high strain rate domain,the development of new grain boundaries is primarily associated with the deformation microbands in the low-temperature deformation domain.As the temperature increased,the high dislocation density accelerated the migration of the grain boundaries.Furthermore,the DRX mechanism changed from continuous DRX to post-DRX.This change in the DRX mechanism type was attributed to the time during which the sample remained high temperature after deformation.

关键词： 40Cr10Si2Mo steel Dynamic recrystallization DRX mechanism Grain boundary dislocation density

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Assessment of Hydrogen Embrittlement Susceptibility and Mechanism(s)in Quench and Tempered AISI 4135 Steel Using A Novel Fast Fracture Test in Bending

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Acta Metallurgica Sinica(English Letters) 2023年第7期36卷 1078-1094页

作者： Tuhin Das Salim V.Brahimi Jun Song Stephen Yue Department of Materials Engineering McGill UniversityMontrealQC H3A OC5Canada Industrial Fasteners Institute ClevelandOH 44131USA

A newly proposed rapid fracture test in four-point bending was used to evaluate the effect of tempering on the hydrogen embrittlement(HE)susceptibility of an AISI 4135 steel,where it was tempered to four different strength(or hardness)levels.It was observed that HE susceptibility increases with the increase in hardness.It was shown that there will be minimal impact of hydrogen(H)on the fracture of materials with hardness 37 HRC and below,even if they are completely saturated with H.On the other hand,H will have similar detrimental effect on fracture properties of quench and tempered(Q and T)steels having hardness higher than 45 HRC.Ductile to brittle transition behavior was observed for a critical hardness(or strength)range as well as for a critical concentration level of H.Additionally,a critical H concentration was observed to exist for each of the strength levels.Fractography was performed in addition to microstructural characterization using transmission electron microscopy(TEM).A very good correlation was observed between the fast fracture test results and fractography.The fast fracture test was further compared with a conventional incremental step load(ISL)test for the evaluation of HE susceptibility.The ISL test results and fracture surface characteristics corroborate very well with the observations from the fast fracture test.This study successfully establishes the fast fracture test as a novel technique to study HE susceptibility and mechanism(s).

关键词： Hydrogen embrittlement(HE) Mechanical testing Fracture mechanics Martensitic steel Hardness dislocation density

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