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18 pages, 19673 KiB

Open AccessArticle

Hot Deformation Behavior of Hastelloy C276 Alloy: Microstructural Variation and Constitutive Models

by Daoguang He, Shibing Chen, Yongcheng Lin, Xintao Yan and Guan Liu

Materials 2023, 16(18), 6192; https://doi.org/10.3390/ma16186192 - 13 Sep 2023

Cited by 3 | Viewed by 1301

Isothermal deformation experiments of the Hastelloy C276 alloy were executed using the Gleeble-3500 hot simulator at a temperature range of 1000–1150 °C and a strain rate range of 0.01–10 s⁻¹. Microstructural evolution mechanisms were analyzed via transmission electron microscope (TEM) and [...] Read more.

Isothermal deformation experiments of the Hastelloy C276 alloy were executed using the Gleeble-3500 hot simulator at a temperature range of 1000–1150 °C and a strain rate range of 0.01–10 s⁻¹. Microstructural evolution mechanisms were analyzed via transmission electron microscope (TEM) and electron backscatter diffraction (EBSD). Results reveal that the influences of hot compression parameters on the microstructure variation features and flow behaviors of the Hastelloy C276 alloy were significant. The intense strain hardening (SH) effects caused by the accumulation of substructures were promoted when the strain rates were increased, and true stresses exhibited a notable increasing tendency. However, the apparent DRV effects caused by the annihilation of substructures and the increasingly dynamic recrystallization (DRX) behaviors occurred at high compressed temperature, inducing the reduction in true stresses. In addition, a physical-based (PB) constitutive model and a long short-term memory (LSTM) model optimized using the particle swarm optimization (PSO) algorithm were established to predict the flow behavior of Hastelloy C276 alloy. The smaller average absolute relative error and greater relation coefficient suggest that the LSTM model possesses a higher forecasting accuracy than the PB model. Full article

(This article belongs to the Special Issue Plasticity, Damage, and Fracture for Lightweight High-Strength Metals)

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24 pages, 16155 KiB

Open AccessArticle

Effect of Er, Si, Hf and Nb Additives on the Thermal Stability of Microstructure, Electrical Resistivity and Microhardness of Fine-Grained Aluminum Alloys of Al-0.25%Zr

by Aleksey V. Nokhrin, Galina S. Nagicheva, Vladimir N. Chuvil’deev, Vladimir I. Kopylov, Aleksandr A. Bobrov and Nataliya Yu. Tabachkova

Materials 2023, 16(5), 2114; https://doi.org/10.3390/ma16052114 - 6 Mar 2023

Cited by 9 | Viewed by 2042

Abstract

The conductor aluminum alloys of Al-0.25wt.%Zr alloyed additionally with X = Er, Si, Hf and Nb were the objects of our investigations. The fine-grained microstructure in the alloys was formed via equal channel angular pressing and rotary swaging. The thermal stability of the [...] Read more.

The conductor aluminum alloys of Al-0.25wt.%Zr alloyed additionally with X = Er, Si, Hf and Nb were the objects of our investigations. The fine-grained microstructure in the alloys was formed via equal channel angular pressing and rotary swaging. The thermal stability of the microstructure, specific electrical resistivity and microhardness of the novel conductor aluminum alloys were investigated. The mechanisms of nucleation of the Al₃(Zr, X) secondary particles during annealing the fine-grained aluminum alloys were determined using the Jones–Mehl–Avrami–Kolmogorov equation. Using the Zener equation, the dependencies of the average secondary particle sizes on the annealing time were obtained on the base of the analysis of the data on the grain growth in the aluminum alloys. The secondary particle nucleation during long-time low-temperature annealing (300 °C, 1000 h) was shown to go preferentially at the cores of the lattice dislocations. The Al-0.25%Zr-0.25%Er-0.20%Hf-0.15%Si alloy subjected to long-time annealing at 300 °C has the optimal combination of microhardness and electrical conductivity (59.8%IACS, Hv = 480 ± 15 MPa). Full article

(This article belongs to the Special Issue Plasticity, Damage, and Fracture for Lightweight High-Strength Metals)

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15 pages, 6308 KiB

Open AccessArticle

Effect of Process Parameters on Properties of Cold-Sprayed Zn–Al Composite Coatings

by Naijiang Wang, Chengxin Liu, Yangang Wang, Hao Chen, Xingrong Chu and Jun Gao

Materials 2022, 15(19), 7007; https://doi.org/10.3390/ma15197007 - 9 Oct 2022

Cited by 4 | Viewed by 1560

Abstract

Al–Zn composite coating can provide effective cathodic protection for E235 steel. This study aims to obtain the Al–Zn composite coating with the best anti-corrosion performance by optimizing the spraying temperature, spraying distance and powder-feeding motor speed. The Al and Zn powders were analyzed [...] Read more.

Al–Zn composite coating can provide effective cathodic protection for E235 steel. This study aims to obtain the Al–Zn composite coating with the best anti-corrosion performance by optimizing the spraying temperature, spraying distance and powder-feeding motor speed. The Al and Zn powders were analyzed by scanning electron microscope (SEM), and the microstructure of the coatings prepared by different process parameters was observed by optical microscope. The mechanical and anticorrosive properties of the coating were evaluated using hardness, porosity, thickness and electrochemical tests. According to the experimental results, when the spraying temperature, spraying distance and powder-feeding motor speed were 500 °C, 27 mm and 1.5 r/min, respectively, the hardness of the coating was 67 HV, the porosity was 0.57% and the thickness was 0.588 mm. The EIS test results show that the coating has the maximum polarization resistance, and therefore the coating has good corrosion resistance at this parameter. Full article

(This article belongs to the Special Issue Plasticity, Damage, and Fracture for Lightweight High-Strength Metals)

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18 pages, 3731 KiB

Open AccessArticle

Some Issues with Statistical Crystal Plasticity Models: Description of the Effects Triggered in FCC Crystals by Loading with Strain-Path Changes

by Alexey Shveykin, Kirill Romanov and Peter Trusov

Materials 2022, 15(19), 6586; https://doi.org/10.3390/ma15196586 - 22 Sep 2022

Cited by 4 | Viewed by 1513

Abstract

The justification of the applicability of constitutive models to exploring technological processes requires a detailed analysis of their performance when they are used to describe loadings including the complex loading mode that is characteristic of these processes. This paper considers the effect of [...] Read more.

The justification of the applicability of constitutive models to exploring technological processes requires a detailed analysis of their performance when they are used to describe loadings including the complex loading mode that is characteristic of these processes. This paper considers the effect of equivalent stress overshooting after the strain-path changes known to occur in metals and alloys. The macrophenomenological and multilevel models, which are based on crystal plasticity, account for this effect by applying anisotropic yield criteria at the macro- and mesolevels, respectively. We introduce a two-level constitutive statistical inelastic deformation model (identified for aluminum) that incorporates the popular simple phenomenological anisotropic hardening law for describing the behavior of FCC polycrystals. The results of the numerical simulation are in satisfactory agreement with existing experimental data. Statistical analysis of the motion of a mesostress in the stress space on the crystallite yield surface is performed. The obtained data are compared with the results found using the isotropic hardening law. The results clarify the simulation details of statistical crystal plasticity models under loading with strain-path changes in materials and demonstrate their suitability for describing the processes under consideration. Full article

(This article belongs to the Special Issue Plasticity, Damage, and Fracture for Lightweight High-Strength Metals)

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12 pages, 6062 KiB

Open AccessArticle

Study on Creep-Fatigue Mechanical Behavior and Life Prediction of Ti₂AlNb-Based Alloy

by Yanju Wang, Xinhao Wang, Yanfeng Yang, Xiang Lan, Zhao Zhang and Heng Li

Materials 2022, 15(18), 6238; https://doi.org/10.3390/ma15186238 - 8 Sep 2022

Cited by 11 | Viewed by 1992

Abstract

Low-cycle fatigue, creep and creep-fatigue tests of Ti₂AlNb-based alloy were carried out at 550 °C. Compared with low-cycle fatigue, a creep-fatigue hysteresis loop has larger area and smaller average stress. The introduction of creep damage will greatly reduce the cycle life, [...] Read more.

Low-cycle fatigue, creep and creep-fatigue tests of Ti₂AlNb-based alloy were carried out at 550 °C. Compared with low-cycle fatigue, a creep-fatigue hysteresis loop has larger area and smaller average stress. The introduction of creep damage will greatly reduce the cycle life, and change the fatigue crack initiation point and failure mechanism. Based on the linear damage accumulation rule, the fatigue damage and creep damage were described by the life fraction method and the time fraction method, respectively, and the creep-fatigue life of the Ti₂AlNb-based alloy is predicted within an error band of ±2 times. Full article

(This article belongs to the Special Issue Plasticity, Damage, and Fracture for Lightweight High-Strength Metals)

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22 pages, 10977 KiB

Open AccessArticle

Precise Modeling of Thermal and Strain Rate Effect on the Hardening Behavior of SiC/Al Composite

by Yanju Wang, Pengfei Wu, Xiaolei He, Wei Zhao, Xiang Lan and Yanshan Lou

Materials 2022, 15(6), 2000; https://doi.org/10.3390/ma15062000 - 8 Mar 2022

Viewed by 1956

Abstract

Temperature and strain rate have significant effects on the mechanical behavior of SiC/Al 2009 composites. This research aimed to precisely model the thermal and strain rate effect on the strain hardening behavior of SiC/Al composite using the artificial neural network (ANN). The mechanical [...] Read more.

Temperature and strain rate have significant effects on the mechanical behavior of SiC/Al 2009 composites. This research aimed to precisely model the thermal and strain rate effect on the strain hardening behavior of SiC/Al composite using the artificial neural network (ANN). The mechanical behavior of SiC/Al 2009 composites in the temperature range of 298–623 K under the strain rate of 0.001–0.1 s⁻¹ was investigated by a uniaxial tension experiment. Four conventional models were adopted to characterize the plastic flow behavior in relation to temperature, strain rate, and strain. The ANN model was also applied to characterize the flow behavior of the composite at different strain rates and temperatures. Experimental results showed that the plastic deformation behavior of SiC/Al 2009 composite possesses a coupling effect of strain, strain rate, and temperature. Comparing the prediction error of these models, all four conventional models could not provide satisfactory modeling of flow curves at different strain rates and temperatures. Compared to the four conventional models, the suggested ANN structure dramatically improved the prediction accuracy of the flow curves at different strain rates and temperatures by reducing the prediction error to a maximum of 4.0%. Therefore, the ANN model is recommended for precise modeling of the thermal and strain rate effect on the flow curves of SiC/Al composites. Full article

(This article belongs to the Special Issue Plasticity, Damage, and Fracture for Lightweight High-Strength Metals)

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36 pages, 12528 KiB

Open AccessArticle

Damage Evolution of Hot Stamped Boron Steels Subjected to Various Stress States: Macro/Micro-Scale Experiments and Simulations

by Hao Zhang, Guoqiang Liu, Ning Guo, Xiangbin Meng, Yanbin Shi, Hangqi Su, Zhe Liu and Bingtao Tang

Materials 2022, 15(5), 1751; https://doi.org/10.3390/ma15051751 - 25 Feb 2022

Cited by 2 | Viewed by 2128

Abstract

Hot stamping components with tailored mechanical properties have excellent safety-related performance in the field of lightweight manufacturing. In this paper, the constitutive relation and damage evolution of bainite, martensite, and mixed bainite/martensite (B/M) phase were studied. Two-dimensional representative volume element (RVE) models were [...] Read more.

Hot stamping components with tailored mechanical properties have excellent safety-related performance in the field of lightweight manufacturing. In this paper, the constitutive relation and damage evolution of bainite, martensite, and mixed bainite/martensite (B/M) phase were studied. Two-dimensional representative volume element (RVE) models were constructed according to microstructure characteristics. The constitutive relations of individual phases were defined based on the dislocation strengthening theory. Results showed that the damage initiation and evolution of martensite and bainite phases can well described by the Lou-Huh damage criterion (DF2015) determined by the hybrid experimental–numerical method. The calibrated damage parameters of each phase were applied to the numerical simulation, followed by the 2D RVE simulations of B/M phase under different stress states. To study the influence of martensite volume fraction (Vm) and distribution of damage evolution, the void nucleation and growth were evaluated by RVEs and verified by scanning electron microscope (SEM). Three types of void nucleation modes under different stress states were experimentally and numerically studied. The results showed that with the increase of Vm and varying martensite distribution, the nucleation location of voids move from bainite to martensite. Full article

(This article belongs to the Special Issue Plasticity, Damage, and Fracture for Lightweight High-Strength Metals)

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17 pages, 6355 KiB

Open AccessArticle

In-Situ Study on Tensile Deformation and Fracture Mechanisms of Metastable β Titanium Alloy with Equiaxed Microstructure

by Jing Wang, Yongqing Zhao, Qinyang Zhao, Chao Lei, Wei Zhou and Weidong Zeng

Materials 2022, 15(4), 1325; https://doi.org/10.3390/ma15041325 - 11 Feb 2022

Cited by 6 | Viewed by 2201

Abstract

Understanding the mechanisms of deformation and fracture of metastable β titanium alloys is of great significance for improving formability and service life. By combining the in-situ tensile test, TEM characterization and EBSD analysis, the tensile deformation behavior, activation of slip systems, crack initiation, [...] Read more.

Understanding the mechanisms of deformation and fracture of metastable β titanium alloys is of great significance for improving formability and service life. By combining the in-situ tensile test, TEM characterization and EBSD analysis, the tensile deformation behavior, activation of slip systems, crack initiation, and propagation of a high strength metastable β titanium alloy (Ti-5Cr-4Al-4Zr-3Mo-2W-0.8Fe) with equiaxed microstructure are investigated. The equiaxed microstructure is composed of primary α (α_p) phase, transformed β (β_t) matrix phase, and secondary α (α_s) phase. In contrast to the hexagonal α_p grain with limited slip systems, the body-centered β_t matrix has more slip systems, however the hindering effect of α_s phases on dislocation slip leads to the different deformability of the α_p phase and β_t matrix. The equiaxed α_p grains are more prone to deformation and rotation to coordinate the overall deformation. The shear band leads to the formation of sub-grain boundary and even the fragmentation of α_p grains. As a result, the microvoids tend to nucleate at the grain boundary, phase interface, slip band, and shear band. The inhomogeneous deformation in the plastic deformation zone around the crack tip is the primary cause of damage. The crack propagation caused by microvoids coalescence advances along the grain boundaries and phase interfaces in the form of intergranular, and along the activated slip systems and shear bands in the form of transgranular. Pinpointing the situation in the equiaxed microstructure and combining that in other typical microstructures will help to summarize the universal deformation and fracture mechanisms of metastable β titanium alloy, and provide a basis for alloy design and microstructure tailoring. Full article

(This article belongs to the Special Issue Plasticity, Damage, and Fracture for Lightweight High-Strength Metals)

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