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14 pages, 14426 KiB

Open AccessArticle

Microstructural Evolution and Strengthening of Dual-Phase Stainless Steel S32750 during Heavily Cold Drawing

by Hong Gao, Zhixun An, Liang Yao, Jianyong Wang, Lili Zhai, Binhua Ding, Jin Peng, Lichu Zhou and Xia Cao

Crystals 2024, 14(7), 621; https://doi.org/10.3390/cryst14070621 - 5 Jul 2024

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Abstract

S32750 dual-phase stainless steel (DSS) wires were prepared by cold drawing with a strain of ε = 0~3.6. The mechanical behavior and microstructural evolution of these DSS wires at different strains were investigated. Specifically, the yield strength and ultimate tensile strength of a [...] Read more.

S32750 dual-phase stainless steel (DSS) wires were prepared by cold drawing with a strain of ε = 0~3.6. The mechanical behavior and microstructural evolution of these DSS wires at different strains were investigated. Specifically, the yield strength and ultimate tensile strength of a S32750 DSS wire at a strain of ε = 3.6 reached 1771 MPa and 1952 MPa, respectively. The microstructure of the wire was transformed into a heterogeneous microstructure, which consisted of ferrite fiber grains and a nanofibrous grain structure consisting of austenite and strain-induced martensite nanofiber grains. A sub-grain structure was observed inside the ferrite fiber. The austenitic phase followed the evolutionary steps of stacking faults, twinning, ε-martensite, α-martensite, and, finally, austenite, before transitioning into a nanofibrous grain structure. This nanofibrous grain structure significantly contributed to the strength compared with the relatively coarse ferrite phase. Full article

(This article belongs to the Special Issue Dislocations and Twinning in Metals and Alloys)

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10 pages, 14914 KiB

Open AccessArticle

Modeling of Texture Development during Metal Forming Using Finite Element Visco-Plastic Self-Consistent Model

by Johannes Kronsteiner, Elias Theil, Alois Christian Ott, Aurel Ramon Arnoldt and Nikolaus Peter Papenberg

Crystals 2024, 14(6), 533; https://doi.org/10.3390/cryst14060533 - 5 Jun 2024

Cited by 2 | Viewed by 1240

Abstract

In directional forming processes, such as rolling and extrusion, the grains can develop preferred crystal orientations. These preferred orientations—the texture—are the main cause for material anisotropy. This anisotropy leads to phenomena such as earing, which occur during further forming processes, e.g., during the [...] Read more.

In directional forming processes, such as rolling and extrusion, the grains can develop preferred crystal orientations. These preferred orientations—the texture—are the main cause for material anisotropy. This anisotropy leads to phenomena such as earing, which occur during further forming processes, e.g., during the deep drawing of sheet metal. Considering anisotropic properties in numerical simulations allows us to investigate the effects of texture-dependent defects in forming processes and the development of possible solutions. Purely phenomenological models for modeling anisotropy work by fitting material parameters or applying measured anisotropy properties to all elements of the part, which remain constant over the duration of the simulation. In contrast, crystal plasticity methods, such as the visco-plastic self-consistent (VPSC) model, provide a deeper insight into the development of the material microstructure. By experimentally measuring the initial texture and using it as an initial condition for the simulations, it is possible to predict the evolution of the microstructure and the resulting effect on the mechanical properties during forming operations. The results of the simulations with the VPSC model show a good agreement with corresponding compression tests and the earing phenomenon, which is typical for cup deep drawing. Full article

(This article belongs to the Special Issue Dislocations and Twinning in Metals and Alloys)

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15 pages, 4670 KiB

Open AccessArticle

Experimental and Modelling Research on the Effect of Prior Ferrite on Bainitic Transformation in Medium-Carbon Bainitic Steel

by Xinpan Yu, Wei Liu, Kang He, Tengfei Wang, Gang Niu and Huibin Wu

Crystals 2024, 14(6), 487; https://doi.org/10.3390/cryst14060487 - 22 May 2024

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Abstract

In this study, we investigate the impact of prior ferrite on the bainite transformation kinetics and microstructure of medium-carbon steel interrupted by an intercritical annealing (IAA) process. It was found that the incubation time and completion time decreased from 687 s and 6018 [...] Read more.

In this study, we investigate the impact of prior ferrite on the bainite transformation kinetics and microstructure of medium-carbon steel interrupted by an intercritical annealing (IAA) process. It was found that the incubation time and completion time decreased from 687 s and 6018 s to 20 s and 4680 s, with the volume fraction of ferrite increasing from 9.5% to 28.6%, while the maximum transformation rate increased from 00271 μm/s to 0.0436 μm/s. The ferrite/austenite interface is introduced, and the nucleation sites are increased to accelerate the subsequent bainite transformation due to the formation of prior ferrite. However, there is a competitive relationship between the number and activation energy of bainite nucleation. According to the experimental results and theoretical calculations, the activation energy of the bainite transformation in the medium-carbon bainite steel decreases gradually with an increase in the volume fraction of prior ferrite. Full article

(This article belongs to the Special Issue Dislocations and Twinning in Metals and Alloys)

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13 pages, 6779 KiB

Open AccessArticle

Molecular Dynamics Simulation of the Interaction between Dislocations and Iron–Vanadium Precipitates in Alpha Iron: Effect of Chemical Composition

by Sepehr Yazdani, Mohsen Mesbah and Veronique Vitry

Crystals 2023, 13(8), 1247; https://doi.org/10.3390/cryst13081247 - 12 Aug 2023

Cited by 4 | Viewed by 1441

Abstract

In this study, molecular dynamics simulations were employed to study the interaction between dislocations with Fe-V precipitate with different vanadium concentrations. Increasing the vanadium concentration in the precipitate results in a strong interaction between the dislocations and the precipitate, and the dislocation line [...] Read more.

In this study, molecular dynamics simulations were employed to study the interaction between dislocations with Fe-V precipitate with different vanadium concentrations. Increasing the vanadium concentration in the precipitate results in a strong interaction between the dislocations and the precipitate, and the dislocation line bows out more as a result of increasing the energy of the dislocation line, and the critical stress needed for depinning the dislocations increases. However, at a low vanadium concentration (1:3 atomic ratio) the dislocations cut through the precipitate without changing the speed. An increasing vanadium concentration not only affects the dislocation shape and movement speed, but also affects the configuration of the junction between the a/2[111] and a/2[100] dislocations, and the void formation after the cutting process. The formation of strong junctions and a high number of voids locks the a/2[111] dislocation motion, and increases the strength of the alloy. The results of the radial distribution function before and after the cutting process show that the structure of the precipitate changes from crystalline to amorphous, and the degree of amorphization decreases with an increasing vanadium concentration. Full article

(This article belongs to the Special Issue Dislocations and Twinning in Metals and Alloys)

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10 pages, 2530 KiB

Open AccessEditor’s ChoiceArticle

In Situ Observation of High Bending Strain Recoverability in Au Nanowires

by Lingyi Kong, Guang Cao, Haofei Zhou and Jiangwei Wang

Crystals 2023, 13(8), 1159; https://doi.org/10.3390/cryst13081159 - 26 Jul 2023

Cited by 3 | Viewed by 1504

Abstract

Metallic nanowires (NW) usually exhibit unique physical, mechanical, and chemical properties compared to their bulk counterparts. Despite extensive research on their mechanical behavior, the atomic-scale deformation mechanisms of metallic nanowires remain incompletely understood. In this study, we investigate the deformation behavior of Au [...] Read more.

Metallic nanowires (NW) usually exhibit unique physical, mechanical, and chemical properties compared to their bulk counterparts. Despite extensive research on their mechanical behavior, the atomic-scale deformation mechanisms of metallic nanowires remain incompletely understood. In this study, we investigate the deformation behavior of Au nanowires embedded with a longitudinal twin boundary (TB) under different loading rates using in situ nanomechanical testing integrated with atomistic simulations. The Au nanowires exhibit a recoverable bending strain of up to 27.5% with the presence of TBs. At low loading rates, the recoverable bending is attributed to the motion of stacking faults (SFs) and their interactions with TBs. At higher loading rates, the formation of high-angle grain boundaries and their reversible migration become dominant in Au nanowires. These findings enhance our understanding of the bending behavior of metallic nanowires, which could inspire the design of nanodevices with improved fatigue resistance and a large recoverable strain capacity. Full article

(This article belongs to the Special Issue Dislocations and Twinning in Metals and Alloys)

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30 pages, 8022 KiB

Open AccessArticle

Self-Consistent Crystal Plasticity Modeling of Slip-Twin Interactions in Mg Alloys

by Mukti Patel, YubRaj Paudel, Shiraz Mujahid, Hongjoo Rhee and Haitham El Kadiri

Crystals 2023, 13(4), 653; https://doi.org/10.3390/cryst13040653 - 10 Apr 2023

Cited by 4 | Viewed by 2293

Abstract

Parsing the effect of slip-twin interactions on the strain rate and thermal sensitivities of Magnesium (Mg) alloys has been a challenging endeavor for scientists preoccupied with the mechanical behavior of hexagonal close-packed alloys, especially those with great latent economic potential such as Mg. [...] Read more.

Parsing the effect of slip-twin interactions on the strain rate and thermal sensitivities of Magnesium (Mg) alloys has been a challenging endeavor for scientists preoccupied with the mechanical behavior of hexagonal close-packed alloys, especially those with great latent economic potential such as Mg. One of the main barriers is the travail entailed in fitting the various stress–strain behaviors at different temperatures, strain rates, loading directions applied to different starting textures. Taking on this task for two different Mg alloys presenting different textures and as such various levels of slip-twin interactions were modeled using visco-plastic self-consistent (VPSC) code. A recently developed routine that captures dislocation transmutation by twinning interfaces on strain hardening within the twin lamellae was employed. While the strong texture was exemplified by traditional rolled AZ31 Mg alloys, the weak texture was represented by ZEK100 Mg alloy sheets. The transmutation model incorporated within a dislocation density based hardening model showed enhanced flexibility in predicting the complex strain rate and thermal sensitive behavior of Mg textures’ response to various mechanical loading schemes. Full article

(This article belongs to the Special Issue Dislocations and Twinning in Metals and Alloys)

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15 pages, 13211 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Dependence of Charpy Impact Properties of Fe-30Mn-0.05C Steel on Microstructure

by Jianchao Xiong, Heng Li, Ling Kong, Xiaodan Zhang, Wenquan Cao and Yuhui Wang

Crystals 2023, 13(2), 353; https://doi.org/10.3390/cryst13020353 - 18 Feb 2023

Cited by 3 | Viewed by 2201

Abstract

Fe-30Mn-0.05C steel specimens with cold-rolled, partially recrystallized, fine-grained, and coarse-grained microstructures were fabricated by means of 80% cold rolling followed by annealing at 550–1000 °C. The initial and deformed microstructures were characterized, and the Charpy impact properties were tested at room temperature (RT) [...] Read more.

Fe-30Mn-0.05C steel specimens with cold-rolled, partially recrystallized, fine-grained, and coarse-grained microstructures were fabricated by means of 80% cold rolling followed by annealing at 550–1000 °C. The initial and deformed microstructures were characterized, and the Charpy impact properties were tested at room temperature (RT) and liquid nitrogen temperature (LNT). It was found that the Charpy absorbed energy increased with the annealing temperature, while the specimens showed different trends: parabolic increase at RT and exponential increase at LNT, respectively. Compared with the fully recrystallized specimens, those with a partially recrystallized microstructure exhibited lower impact energy, especially at LNT. This was because cracks tended to nucleate and propagate along the recovery microstructure where stress concentration existed. The grain size played an important role in the twinning behavior and impact properties. High Charpy impact energy (~320 J) was obtained in the coarse-grained specimen having the grain size of 42.1 μm at both RT and LNT, which was attributed to the activation of high-density deformation twinning. However, deformation twinning was inhibited in the specimen with the average grain size of 3.1 μm, resulting in limited work hardening and lower impact energy. Full article

(This article belongs to the Special Issue Dislocations and Twinning in Metals and Alloys)

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Review

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16 pages, 2359 KiB

Open AccessReview

Properties and Applications of Supersaturated Metastable Alloys Obtained via Electrodeposition

by Roberto Bernasconi, Luca Nobili and Luca Magagnin

Crystals 2024, 14(9), 761; https://doi.org/10.3390/cryst14090761 - 27 Aug 2024

Viewed by 1249

Abstract

Supersaturated alloys can exhibit superior properties and electrodeposition is a cost-effective and versatile technique to produce them. In this review, the chemical, mechanical and structural properties of supersaturated alloys are discussed, and connections with metallic glasses and high entropy alloys are also exposed. [...] Read more.

Supersaturated alloys can exhibit superior properties and electrodeposition is a cost-effective and versatile technique to produce them. In this review, the chemical, mechanical and structural properties of supersaturated alloys are discussed, and connections with metallic glasses and high entropy alloys are also exposed. After discussing mechanisms causing supersaturation in electrodeposited alloys, an overview of the most important electrodeposited metastable alloys is provided, showing that they are mainly used as protective coatings able to improve corrosion resistance and tribological performance of a large variety of industrial components. Composition of the electrolytic baths and deposition parameters are also considered and discussed. Full article

(This article belongs to the Special Issue Dislocations and Twinning in Metals and Alloys)

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