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25 pages, 6539 KiB

Open AccessArticle

Interpretable Calibration of Crystal Plasticity Model Using a Bayesian Surrogate-Assisted Genetic Algorithm

by Shuaiyi Yang, Xuefeng Tang, Lei Deng, Pan Gong, Mao Zhang, Junsong Jin and Xinyun Wang

Metals 2023, 13(1), 166; https://doi.org/10.3390/met13010166 - 13 Jan 2023

Cited by 1 | Viewed by 1490

The accurate calibration of material parameters in crystal plasticity models is essential for applying crystal plasticity (CP) simulations. Identifying these parameters usually requires unfeasible single-crystal experiments or expensive time costs due to the use of traditional genetic algorithm (GA) optimization. This study proposed [...] Read more.

The accurate calibration of material parameters in crystal plasticity models is essential for applying crystal plasticity (CP) simulations. Identifying these parameters usually requires unfeasible single-crystal experiments or expensive time costs due to the use of traditional genetic algorithm (GA) optimization. This study proposed an efficient and interpretable method for calibrating the constitutive parameters with macroscopic mechanical tests. This approach utilized the Bayesian neural network (BNN)-based surrogate-assisted GA (SGA) optimization method to identify a group of constitutive parameters that can reproduce the experimental stress–strain curve and crystallographic orientation by crystal plasticity simulation. The proposed approach was performed on the calibration of typical high-entropy alloy material parameters in two different CP models. The use of the surrogate model reduces the call count of simulation in the parameter searching process and speeds up the calibration significantly. With the help of infill sampling, the accuracy of this optimization method is consistent with the CP simulation and not limited by the accuracy of the surrogate model. Another merit of this method is that the pattern that the BNN surrogate found in the model parameters can be interpreted with its integrated gradients, which helps us to understand the relationship between constitutive parameters and the output mechanical response. The interpretation of BNN can guide further experiment design to decouple particular parameters and add constraints provided by the attached experiment or prior knowledge. Full article

(This article belongs to the Special Issue Plastic Forming, Microstructure, and Property Optimization of Metals)

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13 pages, 6182 KiB

Open AccessArticle

Tailoring the Pore Structure of Porous Ni-Sn Alloys for Boosting Hydrogen Evolution Reaction in Alkali Solution

by Junsheng Yang, Jie Li, Ying Wang, Shijie Dong, Yiquan Fan, Wenkang Liu, Yijian Kuang, Siwei Tan, Gan Xiao, Baogang Wang and Zhensen Yu

Metals 2022, 12(12), 2123; https://doi.org/10.3390/met12122123 - 9 Dec 2022

Cited by 4 | Viewed by 1382

Abstract

Ni-based alloy is an ideal candidate for its application in the field of hydrogen evolution of water splitting due to its good durability, excellent catalytic properties and low hydrogen evolution overpotential. In this paper, porous Ni-Sn alloy materials were prepared by activation reaction [...] Read more.

Ni-based alloy is an ideal candidate for its application in the field of hydrogen evolution of water splitting due to its good durability, excellent catalytic properties and low hydrogen evolution overpotential. In this paper, porous Ni-Sn alloy materials were prepared by activation reaction sintering, and the pore structure was tailored by adjusting Sn content. The effects of Sn content and electrolyte temperature on the hydrogen evolution properties of porous Ni-Sn alloy electrodes in 6 mol·L⁻¹ KOH solution were studied by electrochemical measurement methods, such as cyclic voltammetry (CV) curves, electrochemical impedance spectroscopy (ESI) and linear sweep voltammetry, and the mechanism of hydrogen evolution was further discussed. The experimental results reveal that when Sn content is 45 wt%, porous Ni-Sn alloy exhibits the best catalytic performance for hydrogen evolution with a Tafel slope of 164.69 mV·dec⁻¹ and an overpotential of 170 mV. The tested electrode also shows good stability for hydrogen evolution in alkaline solution, and the apparent activation energy calculated at room temperature is 29.645 kJ·mol⁻¹. The catalytic mechanism of hydrogen evolution is as follows: the addition of Sn significantly reduces the dissociation degree of M-H bonds, thereby reducing the overpotential of hydrogen evolution; with the increase of Sn content, the porous Ni-Sn electrode displays a higher electrochemical active surface area (ECSA), which makes porous Ni-Sn alloy exhibit good hydrogen evolution catalytic performance. Full article

(This article belongs to the Special Issue Plastic Forming, Microstructure, and Property Optimization of Metals)

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20 pages, 9543 KiB

Open AccessArticle

Plastic Behavior and Microstructure Heterogeneity of an AA6063-T6 Aluminum Alloy Processed by Symmetric and Asymmetric Rolling

by Jairo Alberto Muñoz, Tarek Khelfa, Gonzalo Ariel Duarte, Martina Avalos, Raúl Bolmaro and José María Cabrera

Metals 2022, 12(10), 1551; https://doi.org/10.3390/met12101551 - 20 Sep 2022

Cited by 4 | Viewed by 3076

Abstract

Rolling is one of the most employed industrial processes which can be used at multiple manufacturing stages, allowing different geometries such as plates, rods, profiles, billets, slabs, tubes, and seamless tubes to be obtained. However, rolled products develop anisotropy due to the preferential [...] Read more.

Rolling is one of the most employed industrial processes which can be used at multiple manufacturing stages, allowing different geometries such as plates, rods, profiles, billets, slabs, tubes, and seamless tubes to be obtained. However, rolled products develop anisotropy due to the preferential orientation of crystals in the rolling direction. Thus, some process configurations and different processing parameters (e.g., thickness reduction per rolling pass, deformation routes, roll diameters, and strain rate) have been proposed to deal with the desired anisotropy. In this context, this investigation evaluates and compares the effect of symmetrical and asymmetrical rolling on an aluminum alloy sheet deformed until a 38% thickness reduction using multiple rolling passes. The asymmetrical process displayed larger texture and microstructure gradients across the sheet thickness than the symmetrical one, manifested as more grain refinement and more intense shear texture components close to sheet surfaces. In terms of plastic anisotropy, the visco-plastic self-consistent model predicted higher average anisotropy for the symmetric rolling than the asymmetric process due to a strong combination of recrystallization and deformation texture components. Conversely, the asymmetric process showed lower planar anisotropy values due to the increase in the fraction of shear and deformation texture components near the sheet surfaces, producing a less intense overall texture than the symmetric rolling. The additional shear strain component was mainly responsible for the material strengthening and texture weakening after the asymmetrical rolling process. In addition, the shear strain produced grain refinement, decreased misorientation, and higher dislocation densities than the as-received and symmetrically rolled materials. After asymmetrical rolling, the microstructure and texture showed heterogeneous profiles across the sheet thickness. This gave rise to a heterogeneous grain size refinement, decreased misorientation close to sheet edges, and plastic gradients. Full article

(This article belongs to the Special Issue Plastic Forming, Microstructure, and Property Optimization of Metals)

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17 pages, 4223 KiB

Open AccessArticle

Pure-Bend and Over-Bend Straightening Theory for In-Plane Curved Beams with Symmetrical Section and Straightening Mechanism Analysis

by Chunge Wang, Gaochao Yu, Jun Zhao and Wen Liu

Metals 2022, 12(8), 1362; https://doi.org/10.3390/met12081362 - 16 Aug 2022

Viewed by 2049

Abstract

Straightening is an important process in the production and application of shafts, tubes, and various profiles. According to the springback theory of small curvature plane bending, the pure bending process and springback of in-plane curved beam with symmetrical section were analyzed, and the [...] Read more.

Straightening is an important process in the production and application of shafts, tubes, and various profiles. According to the springback theory of small curvature plane bending, the pure bending process and springback of in-plane curved beam with symmetrical section were analyzed, and the over-bend straightening theory was established. Based on this, the straightening mechanism of the existing over-bend straightening process was revealed; that is, a zigzag straightening moment was applied in the three-point multi-step straightening process to approximate the smooth curve of theoretical moment, while the multi-point one-time straightening technology was to discretize the theoretical curve using the broken line, so both of them needed a load correction coefficient to compensate the error between the actual load and theoretical calculation. In order to realize the complete loading of theoretical curve, a new technology of three-roll continuous straightening was further proposed and the experimental equipment for shafts and tubes was built. In order to match the characteristics of a pipe section, an accurate moment calculation equation was established. Three-roll continuous straightening experiments of the tube showed that the straightness of the straightened workpiece could be controlled within 1.5‰, which meets the standard requirements. Therefore, it is suggested that the over-bend straightening theory can predict the load required for straightening in-plane curved parts with any symmetrical cross-section, and the three-roller continuous straightening process is an efficient and highly accurate straightening technique. Full article

(This article belongs to the Special Issue Plastic Forming, Microstructure, and Property Optimization of Metals)

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15 pages, 18587 KiB

Open AccessArticle

Eutectic Reaction and Microstructure Stability in CoCrFeNiNb_x High-Entropy Alloys

by Xu Cao, Changjun Wu, Ya Liu, Haoping Peng and Xuping Su

Metals 2022, 12(5), 756; https://doi.org/10.3390/met12050756 - 28 Apr 2022

Cited by 10 | Viewed by 2240

Abstract

Seven arc-melted and then annealed CoCrFeNiNb_x (x = 0.3–0.6) alloys are experimentally and thermodynamically investigated in the present work. All the as-cast and 1000 °C annealed CoCrFeNiNb_x alloys are composed of face-centered cubic (FCC) and C14 Laves phases. Nb content in [...] Read more.

Seven arc-melted and then annealed CoCrFeNiNb_x (x = 0.3–0.6) alloys are experimentally and thermodynamically investigated in the present work. All the as-cast and 1000 °C annealed CoCrFeNiNb_x alloys are composed of face-centered cubic (FCC) and C14 Laves phases. Nb content in the C14 phase stays at around 24.5 at.%, and the Liquid → FCC + C14 eutectic reaction occurred at around 10.8 at.% Nb in a narrow temperature range. It is found that the microstructure in the CoCrFeNiNb_x alloys is dramatically affected by the cooling rate and annealing treatment. The C14 phase easily spheroidizes and coarsens under high temperature, which indicates that the interface energy between FCC and C14 is very large. Moreover, the solubility of Nb in the FCC phase decreases with decreasing temperature. After annealing at 800 °C, a needle-like nano Mg₃Cd-type τ phase precipitates from the pro-eutectic FCC phase and increases alloy hardness for ~100 HV. This should be a method to strengthen alloys. Full article

(This article belongs to the Special Issue Plastic Forming, Microstructure, and Property Optimization of Metals)

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10 pages, 3479 KiB

Open AccessArticle

Effect of Ge Addition on Magnetic Properties and Crystallization Mechanism of FeSiBPNbCu Nanocrystalline Alloy with High Fe Content

by Haijie Zhang, Fushan Bai, Yaqiang Dong, Lei Xie, Qiang Li, Aina He and Jiawei Li

Metals 2022, 12(4), 640; https://doi.org/10.3390/met12040640 - 8 Apr 2022

Cited by 1 | Viewed by 1431

Abstract

In this work, new Ge-containing Fe-based nanocrystalline alloys with the composition of Fe_80.2Si₃B_12-xP₂Nb₂Cu_0.8Ge_x (x = 0, 1, 2 at.%) were developed, and the effects of Ge content on [...] Read more.

In this work, new Ge-containing Fe-based nanocrystalline alloys with the composition of Fe_80.2Si₃B_12-xP₂Nb₂Cu_0.8Ge_x (x = 0, 1, 2 at.%) were developed, and the effects of Ge content on the magnetic and crystallization processes of the alloys were investigated. The addition of Ge extends the annealing window of the present Fe-based alloys, which reaches 173.6 K for the alloy of x = 2. The nanocrystalline alloy of x = 2, composed of dense and uniformly distributed α-Fe grains with an average grain size of 15.7 nm precipitated in the amorphous matrix, was obtained by conventional annealing treatment at a temperature of 843 K for 10 min, and this nanocrystalline alloy exhibited excellent magnetic properties with the H_c of 3 A/m and B_s of 1.65 T, which has great potential for industrial application. Non-isothermal crystallization kinetics studies show that the nucleation activation energy of the alloys gradually decreases with the increase in Ge content. The primary crystallization process is dominated by the direct growth of pre-existing nuclei in the as-spun alloy ribbons, and these pre-existing nuclei provide numerous heterogeneous nucleation sites to form dense and uniform α-Fe nanocrystals with a fine grain size, which leads to the excellent magnetic properties of the present Ge-containing Fe-based nanocrystalline alloys. Full article

(This article belongs to the Special Issue Plastic Forming, Microstructure, and Property Optimization of Metals)

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20 pages, 57683 KiB

Open AccessArticle

Explicit Analysis of Sheet Metal Forming Processes Using Solid-Shell Elements

by Qiao-Min Li, Zhao-Wei Yi, Yu-Qi Liu, Xue-Feng Tang, Wei Jiang and Hong-Jun Li

Metals 2022, 12(1), 52; https://doi.org/10.3390/met12010052 - 27 Dec 2021

Cited by 5 | Viewed by 2456

Abstract

To simulate sheet metal forming processes precisely, an in-house dynamic explicit code was developed to apply a new solid-shell element to sheet metal forming analyses, with a corotational coordinate system utilized to simplify the nonlinearity and to integrate the element with anisotropic constitutive [...] Read more.

To simulate sheet metal forming processes precisely, an in-house dynamic explicit code was developed to apply a new solid-shell element to sheet metal forming analyses, with a corotational coordinate system utilized to simplify the nonlinearity and to integrate the element with anisotropic constitutive laws. The enhancing parameter of the solid-shell element, implemented to circumvent the volumetric and thickness locking phenomena, was condensed into an explicit form. To avoid the rank deficiency, a modified physical stabilization involving the B-bar method and reconstruction of transverse shear components was adopted. For computational efficiency of the solid-shell element in numerical applications, an adaptive mesh subdivision scheme was developed, with element geometry and contact condition taken as subdivision criteria. To accurately capture the anisotropic behavior of sheet metals, material models with three different anisotropic yield functions were incorporated. Several numerical examples were carried out to validate the accuracy of the proposed element and the efficiency of the adaptive mesh subdivision. Full article

(This article belongs to the Special Issue Plastic Forming, Microstructure, and Property Optimization of Metals)

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22 pages, 8585 KiB

Open AccessArticle

Numerical Analysis and Parameter Optimization of Wear Characteristics of Titanium Alloy Cross Wedge Rolling Die

by Zhanshuo Peng, Hongchao Ji, Xiaomin Huang, Baoyu Wang, Wenchao Xiao and Shufu Wang

Metals 2021, 11(12), 1998; https://doi.org/10.3390/met11121998 - 10 Dec 2021

Cited by 6 | Viewed by 2136

Abstract

Cross wedge rolling has the advantages of high production efficiency, good product quality, high material utilization, environmental protection, and low cost. It is one of the best processing methods for producing shaft blanks. In this paper, a cross wedge rolling die of TC4 [...] Read more.

Cross wedge rolling has the advantages of high production efficiency, good product quality, high material utilization, environmental protection, and low cost. It is one of the best processing methods for producing shaft blanks. In this paper, a cross wedge rolling die of TC4 titanium alloy is studied. Based on the Archard wear model, a modified model suitable for cross wedge rolling die wear analysis is derived through finite element simulation. Then, the modified Archard wear model is imported into Deform-3D software for finite element analysis. Orthogonal experimental design is used to combine and analyze different process parameters. Finally, the beetle antennae search (BAS)-genetic algorithm (GA)-back propagation neural network (BPNN) algorithm is used to predict the degree of die wear and to optimize the simulation parameters, which can acquire the process parameters that have the least impact on die wear. The results show that the wear distributions of cross wedge rolling tools is uneven. In general, the most serious areas are basically concentrated in the wedge-shaped inclined plane and rectangular edge lines. The reason is that the tangential force and radial force received by the die are relatively large, which leads to increased wear. Moreover, the temperature change is most severe on the wedge-shaped ridge line. When in contact with the workpiece, the temperature rises sharply, which makes the local temperature rise, the mold hardness decrease, and the wear accelerate. Through response surface method (RSM) analysis, it is concluded that the deformation temperature is the main factor affecting wear depth, followed by the forming angle, and that there is an interaction between the two factors. Finally, the feasibility of the BAS-GA-BP algorithm for optimizing the wear behavior of dies is verified, which provides a new process parameter optimization method for the problem of die wear in the cross wedge rolling process. Full article

(This article belongs to the Special Issue Plastic Forming, Microstructure, and Property Optimization of Metals)

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