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Micromechanical study of the loading path effect in high cycle fatigue

INTERNATIONAL JOURNAL OF FATIGUE 2014年 59卷 64-75页

作者： Guerchais, R. Robert, C. Morel, F. Saintier, N. LAMPA Arts & Metiers ParisTech F-49035 Angers France Univ Bordeaux 1 Arts & Metiers ParisTech UMR CNRS I2M 5295 F-33405 Talence France

In this work, an analysis of both the mechanical response at the grain scale and high cycle multiaxial fatigue criteria is undertaken using finite element (FE) simulations of polycrystalline aggregates. The metallic material chosen for investigation, a pure copper, has a Face Centred Cubic (FCC) crystalline structure. Two-dimensional polycrystalline aggregates, which are composed of 300 randomly orientated equiaxed grains, are loaded at the median fatigue strength defined at 10 cycles. In order to analyse the effect of the loading path on the local mechanical response, combined tension torsion and biaxial tension loading cases, in-phase and out-of-phase, with different biaxiality ratios, are applied to each polycrystalline aggregate. Three different material constitutive models assigned to the grains are investigated: isotropic elasticity, cubic elasticity and crystal plasticity in addition to the cubic elasticity. First, some aspects of the mechanical response of the grains are highlighted, namely the scatter and the multiaxiality of the mesoscopic responses with respect to an uniaxial macroscopic response. Then, the distributions of relevant mechanical quantities classically used in fatigue criteria are analysed for some loading cases and the role of each source of anisotropy on the mechanical response is evaluated and compared to the isotropic elastic case. In particular, the significant influence of the elastic anisotropy on the mesoscopic mechanical response is highlighted. Finally, an analysis of three different fatigue criteria is conducted, using mechanical quantities computed at the grain scale. More precisely, the predictions provided by these criteria, for each constitutive model studied, are compared with the experimental trends observed in metallic materials for such loading conditions. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Multiaxial high cycle fatigue microstructure modeling Anisotropic elasticity Crystal plasticity Fatigue criterion

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Semisolid casting of automotive component: Water pump lid

SEMI-SOLID PROCESSING OF ALLOYS AND COMPOSITES

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SEMI-SOLID PROCESSING OF ALLOYS AND COMPOSITES 2006年 116-117卷 88-91页

作者： Wang, H. Xu, J. Univ So Queensland Fac Engn & Surveying Toowoomba Qld 4350 Australia Gen Res Inst NonFerrous Met Beijing 100088 Peoples R China

Water pump lid is selected as the automotive component to be cast using semisolid casting technology. Semisolid feedstock of alloy A357 was produced by a vertical continuous DC casting with electromagnetic stirring. Non-dendritic structure was obtained in the feedstock billets. A 6-station induction beating system was developed for feedstock billet reheating. Multi-stage reheating and well controlled reheating process resulted in a uniform temperature profile in the billet. Semisolid casting was carried out in a conventional high pressure die casting machine. Die design and casting parameters were adjusted to be suitable for semisolid casting. Compared with the conventional liquid melt casting, semisolid casting resulted in a much higher microstructural integrity with reduced shrinkage porosity.

关键词： semisolid metal processing microstructure modeling Al-Si alloy

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A multiscale microstructure model of cement paste sulfate attack by crystallization pressure

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MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING 2017年第6期25卷 1-1页

作者： Feng, Pan Bullard, Jeffrey W. Garboczi, Edward J. Miao, Changwen Southeast Univ Sch Mat Sci & Engn Jiangsu Key Lab Construct Mat Nanjing 211189 Jiangsu Peoples R China NIST Mat & Struct Syst Div Engn Lab Gaithersburg MD 20878 USA NIST Mat Reliabil Div Mat Measurement Lab Boulder CO 80305 USA Jiangsu Res Inst Bldg Sci Co Ltd Nanjing 210008 Jiangsu Peoples R China

A recent microstructural model of near-surface external sulfate attack on cement paste is modified to incorporate diffusive ionic transport between the surface and interior of a macroscopic specimen that has been hydrated for 100 d prior to exposure to sulfates. The model estimates the driving force for local expansive growth of the Al2O3 - Fe2O3-tri (AFt) phase in terms of crystallization pressure, and the strain and stress fields are tracked within the microstructure with micrometer-scale resolution using a linear elastic finite element model. Damage induced by expansion modifies both the local effective transport properties and linear elastic properties of the local microstructure at different depths, and thereby potentially alters the rates of sulfate ingress and expansion. Therefore, the progress of phase transformations and expansion from the surface to the interior of the porous material is dictated by the rate of ingress of concentration fronts of both sulfate ions and pH, which do not necessarily coincide. The model is used to relate microscopic changes in the structure of cement paste, induced by ingress of sodium sulfate solutions of different concentrations, to the macroscopic expansion, and the results are compared with previous models and published experimental data. The model demonstrates what has previously been assumed in sulfate-attack models, namely that volumetric expansion of macroscopic paste samples in the early stages of sulfate attack is a linear function of the mass of AFt phase precipitated. In addition, the model captures the main features of the evolution of local elastic and transport properties within a macroscopic paste sample, showing an apparently parabolic dependence on depth of the local Young's modulus and local formation factor.

关键词： cement paste sulfate attack microstructure modeling crystallization pressure degradation

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Friction Stir Radial Backward Extrusion (FSRBE) as a new grain refining technique

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ARCHIVES OF CIVIL AND MECHANICAL ENGINEERING 2018年第4期18卷 1374-1385页

作者： Jafarzadeh, Hossein Babaei, Alireza Esmaeili-Goldarag, Firooz Islamic Azad Univ Dept Mech Engn Tabriz Branch Tabriz Iran UCNA Dept Mech Engn Tabriz Iran

A new method entitled Friction Stir Radial Backward Extrusion (FSRBE) is presented for processing fine-grained tubes. In FSRBE technique, an initial pure copper billet is placed inside a cylindrical chamber. The billet is pushed toward a rotating tool which results in radial and backward flow of the material while is frictionally stirred. The microstructure evolution during FSRBE was investigated through experimental observations and cellular automaton (CA) modeling. The observations reveal that the microstructure with initial grain size of 75 mu m was refined to a fine-grained structure with an average grain size of 12 mm. The results of tensile tests demonstrate slight improvement in the value of yield and ultimate strength, elongation and microhardness. The microstructural evolution during FSRBE processing in the micro-level was studied using a coupled cellular automaton algorithm and finite element model. First, the macroscopic plastic flow behavior of material during FSRBE was calculated using FEM simulation method. Next, by tracing the plastic strain, the strain rate and temperature, in the deformation domain of cellular automaton, the DRX kinetics of pure copper is obtained in a devised post-processing step. The microstructure observations showed that the proposed model predictions were in reasonably good agreement with the experimentally obtained results. (c) 2018 Politechnika Wroclawska. Published by Elsevier B.V. All rights reserved.

关键词： Friction Stir, Radial Backward Extrusion Fine-grained structure microstructure modeling Cellular automaton

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A coupled micro-meso-scale study on the damage mechanism of 2D SiC/SiC ceramic matrix composites

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MECHANICS OF ADVANCED MATERIALS AND STRUCTURES 2021年第20期28卷 2083-2095页

作者： Hui, Xinyu Xu, Yingjie Hou, Yuliang Northwestern Polytech Univ State IJR Ctr Aerosp Design & Addit Mfg Xian 710072 Shaanxi Peoples R China Northwestern Polytech Univ Shaanxi Engn Lab Aerosp Struct Design & Applicat Xian Shaanxi Peoples R China Zhengzhou Univ Sch Mech & Power Engn Zhengzhou Henan Peoples R China

A coupled micro-meso-scale modeling strategy is proposed to investigate the damage mechanism of 2D SiC/SiC ceramic matrix composites. The multi-scale modeling begins with microstructure construction using the representative volume elements (RVE). The effective properties of the SiC/SiC yarn are computed using the micro-scale RVE model. At meso-scale, the Tsai-Wu and Mohr's failure criteria are used to describe the different failure modes of yarn and matrix. A satisfied agreement with experimental results obtained by uniaxial tension tests validates the proposed multi-scale modeling strategy. The damage behavior of 2D SiC/SiC composites under in-plane shear loading is further investigated.

关键词： SiC SiC composites damage mechanism progressive damage microstructure modeling representative volume element finite element method

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Study on microstructure and Tensile Behavior of X70 Dual-Phase Steel in Different Directions: Experiments and Crystal Plasticity Finite Element Method

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JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE 2024年第7期34卷 5879-5890页

作者： Lu, Xinxin Qiao, Guiying Xu, Lingzhi Gu, Yu Xu, Kai Chen, Xiaowei Xiao, Furen Yanshan Univ Sch Environm & Chem Engn Hebei Key Lab Heavy Met Deep Remediat Water & Reso Qinhuangdao 066004 Peoples R China Yanshan Univ Coll Mat Sci & Engn Key Lab Metastable Mat Sci & Technol Hebei Key Lab Optimizing Met Prod Technol & Perfor Qinhuangdao 066004 Peoples R China ZhouKou Normal Univ Sch Mech & Elect Engn Zhoukou 466000 Peoples R China CNPC Bohai Equipment Julong Steel Pipe Co Ltd Qingxian 062658 Hebei Peoples R China

Thick-walled X70 dual-phase subsea pipeline steel meets high strength, plasticity conditions. The pipeline characteristics of large wall thickness and small pipe diameter are beneficial for bending and crushing resistance. It can adapt to the subsea environment to ensure the safety and reliability of the pipeline. In this study, the transverse direction (TD) and rolling direction (RD) mechanical properties of X70 dual-phase steel were compared. The microstructural characteristics in different directions were investigated. Based on the crystal plasticity framework, the two-dimensional (2D) representative volume element models of TD and RD microstructure were established. The influence of the microstructural characteristics on mechanical properties was discussed. The results show that the banded bainite in RD has better deformation compatibility. The refinement of ferrite grain size in TD improves strength and plasticity to some extent. However, the bainite morphology significantly affects the deformation compatibility of X70 dual-phase steel compared to refined ferrite grain. The primary slip system of bainite is {110} < 111 > , and the shear strain localization of bainite occurs in the bainite edge region in both (011)[11-1]and (1-12)[-111] directions. The blocky bainite of TD tended to cause strain concentration, which induces the generation of cracks and eventually leads to material fracture.

关键词： anisotropy crystal plasticity framework mechanical properties microstructure characteristics microstructure modeling subsea pipeline steel

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Generating polycrystalline microstructures with prescribed tensorial texture coefficients

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COMPUTATIONAL MECHANICS 2022年第3期70卷 639-659页

作者： Kuhn, Jannick Schneider, Matti Sonnweber-Ribic, Petra Boehlke, Thomas Robert Bosch GmbH Corp Sect Res & Adv Engn Renningen Germany Karlsruhe Inst Technol KIT Inst Engn Mech Karlsruhe Germany

This work is concerned with synthetic microstructure models of polycrystalline materials. Once a representation of the microstructure is generated, the individual grains need to be furnished with suitable crystal orientations, matching a specific crystal orientation distribution. We introduce a novel method for this task, which permits to prescribe the orientations based on tensorial Fourier coefficients. This compact representation gives rise to the texture coefficient optimization for prescribing orientations method, enabling the determination of representative orientations for digital polycrystalline microstructures. We compare the proposed method to established and dedicated algorithms in terms of the linear elastic as well as the non-linear plastic behavior of a polycrystalline material.

关键词： Polycrystalline microstructures Crystal plasticity Multiscale methods microstructure modeling Crystallographic texture

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modeling the Stress-Strain Curves and Dynamic Recrystallization of Nickel-Based A230 Alloy During Hot Deformation

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METALS AND MATERIALS INTERNATIONAL 2022年第12期28卷 3016-3032页

作者： Yu, Jeyong Moon, In Yong Jeong, Hi Won Lee, Ho Won Kim, Ji Hoon Kang, Seong-Hoon Korea Inst Mat Sci Chang Won 51508 South Korea Pusan Natl Univ Sch Mech Engn Busan South Korea

The stress-strain curves and recrystallization behavior of materials during high-temperature deformation can generally be modeled using the Zener-Hollomon parameters expressed as a function of strain, temperature, and activation energy. However, reports of the effects of the activation energy with respect to the variation in the strain rate during hot deformation on the modeled stress-strain curves are limited. Therefore, in this study, the effect of the activation energy on the stress-strain curves was analyzed. For this purpose, uniaxial compression tests at temperatures of 900-1200 degrees C and strain rates of 0.001-1 s(-1) were performed using a nickel-based A230 alloy. Using the measured stress-strain curves, constitutive modeling based on the Zener-Hollomon parameters was performed. To analyze the effect of the activation energy at different strain rates on the modeling accuracy, two types of models derived using the strain-rate-dependent and strain-rate-independent activation energies were established. Then, two types of flow stresses were calculated using the models, and their accuracies were compared using the average absolute relative error. In addition, the dynamic recrystallization (DRX) behavior was modeled by applying the derived Zener-Hollomon parameters. Finally, the established DRX kinetic model was applied to finite element simulations to predict the microstructure of the deformed specimen. As a result, it was found that the volume fraction of DRX grains and the grain size, which greatly affect the mechanical properties of the material, can be predicted.

关键词： Dynamic crystallization Zener-Hollomon parameter High-temperature deformation microstructure improvement microstructure modeling

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A High-Temperature Strain-Compensated Arrhenius-Type Constitutive Model and an Improved Avrami-Type Dynamic Recrystallization Model of 40CrNiMo

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JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE 2024年第18期33卷 9893-9910页

作者： Huo Yuan-ming Huo Cun-long He Tao Hosseini, Seyed Reza Elmi Chen Gang Jia Chang-yuan Liu Ke-ran Wang Bao-yu Du Xiang-yang Shanghai Univ Engn Sci Sch Mech & Automot Engn Shanghai 201620 Peoples R China Iran Univ Sci & Technol IUST Sch Met & Mat Engn Tehran Iran Univ Sci & Technol Beijing Sch Mech Engn Beijing 100083 Peoples R China

The flow stress of a metallic material is one of the important parameters to measure the plastic deformability of a material. The quality of the microstructure reflects the forming quality and reliability of a part. Therefore, a high-quality flow stress and microstructure models are very important for the optimization of the process parameters. The flow stress and dynamic recrystallization (DRX) law of the 40CrNiMo axle steel were obtained by performing a thermal simulation compression test and metallography examination. The effects of deformation temperatures, strain rates, and initial grain sizes on the DRX and flow curves were discussed. A strain-compensated Arrhenius-type flow stress equation was established. Considering the influence of the deformation temperatures, strain rates, and initial grain sizes on DRX, a kinetic model and an average grain size evolution model for DRX were established. Statistical and finite element (FE) simulation methods were used to verify the predictability and validity of the flow stress and the microstructure models, which provides an important basis for the study of hot forming of the 40CrNiMo steel.

关键词： constitutive modeling dynamic recrystallization hot deformation microstructure modeling railway axle steel

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Parameter study of extrusion simulation and grain structure prediction for 6xxx alloys with varied Fe content

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MATERIALS TODAY COMMUNICATIONS 2024年 38卷

作者： Hovden, S. Kronsteiner, J. Arnoldt, A. Horwatitsch, D. Kunschert, G. Oesterreicher, J. A. AIT Austrian Inst Technol LKR Light Met Technol A-5282 Ranshofen Austria

Increasing the recycled content is key to improve the sustainability of aluminum wrought alloys. However, Al scrap is often contaminated with Fe. Thus, coping with elevated Fe contents of wrought alloys is essential, but more Fe leads to more intermetallic phases, which impact extrudability and Peripheral Coarse Grain (PCG) formation. Coarse grains at the surfaces of aluminum extrudates can have a major detrimental influence on ductility, corrosion, and fatigue behavior. Therefore, it is desired to minimize the formation of PCG while keeping up the productivity of the process. PCG formation is dependent on local state variables such as temperature, strain, and strain rate, and second phase particles. In this work, we study extrusion of the aluminum alloys EN AW-6060, EN AW-6005A and EN AW-6082 with standard and increased Fe contents (0.2 and 0.7 wt. %). A parameter study of extrusion simulations was performed using the commercial extrusion software Altair (R) InspireTM Extrude Metal. Ram speed, billet temperature, and tooling temperature were varied, for a total of 245 simulations for each alloy. In order to tackle the large number of simulations and to increase computational efficiency, the evolution of microstructure was calculated after the extrusion simulation. For this purpose, the local state variables temperature, strain, and strain rate, were taken from a plane cut of the profile. These parameters along with experimentally determined initial microstructural properties (before extrusion) were used as input for a stand-alone microstructure simulation code. The final grain size distribution output of the microstructure simulations was compared to the microstructure obtained after extrusion experiments. In this way, our work furthers the understanding of the relationships between alloy composition, process parameters, and PCG formation.

关键词： microstructure modeling Metal extrusion FEM Parameter study PCG

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