The coupling of thermal and athermal effect in high-density multiple pulse continuous treatment of AZ31

Wang, Ruijuan; Xu, Zhuohui; Jiang, Yong; Tang, Guoyi; Wan, Junxi; Chou, Kevin Jenn-Chien; Li, Qiulin

doi:10.1016/j.matdes.2022.110495

Cited by 13 publications

(5 citation statements)

References 34 publications

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“…We investigate the 'room temperature' electropulsing condition and its effects on metallic alloys by tuning the parameters. It is important to note the difference in electropulsing conditions typically used in literature, where appreciable temperature rise is part of the process [19][20][21][22]. Researchers have shown that properly tuning electropulsing parameters can increase dislocation mobility, accelerate vacancy movements, and reform the microstructure of materials by refining the grain size and structure [23][24][25].…”

Section: Introductionmentioning

confidence: 99%

“…and use the electron wind force as the primary driving stimulus. Since the temperature rise in sample during electropulsing is proportional to the square of current density [19], we limit the temperature rising by incorporating 10-100 times lower current density than usual electropulsing treatment. In this study, we monitor the sample temperature in real time to ensure that the specimen temperature remains within 30 °C.…”

Section: Introductionmentioning

confidence: 99%

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Room temperature control of grain orientation via directionally modulated current pulses

Rahman,

Oh,

Waryoba

et al. 2023

Mater. Res. Express

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Traditional approaches to control the microstructure of materials, such as annealing, require high temperature treatment for long periods of time. In this study, we present a room temperature microstructure manipulation method by using the mechanical momentum of electrical current pulses. In particular, a short burst of high-density current pulses with low duty cycle is applied to an annealed FeCrAl alloy, and the corresponding response of microstructure is captured by using Electron Backscattered Diffraction (EBSD) analysis. We show evidence of controllable changes in grain orientation at specimen temperature below 28 C. To demonstrate such microstructural control, we apply the current pulses in two perpendicular directions and observe the corresponding grain rotation. Up to 18 of grain rotation was observed, which could be reversed by varying the electropulsing direction. Detailed analysis at the grain level reveals that electropulsing in a specific direction induces clockwise rotation from their pristine state, while subsequent cross-perpendicular electropulsing results in an anticlockwise rotation. In addition, our proposed room temperature processing yields notable grain refinement, while the average misorientation and density of low-angle grain boundaries (LAGBs) remain unaltered. The findings of this study highlight the potentials of 'convective diffusion' in electrical current based materials processing science towards microstructural control at room temperature.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Room temperature control of grain orientation via directionally modulated current pulses

Rahman,

Oh,

Waryoba

et al. 2023

Mater. Res. Express

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“…It is well-established that the peak temperature increment induced by a singular electropulse is quantitatively related to the current density. As detailed in [39], this temperature rise, denoted as ∆𝑇 , is governed by the following relationship:…”

Section: Microstructure and Grain Boundaries (Gbs) Evolutionmentioning

confidence: 99%

“…where 𝑡 is the pulse width, ρ is the resistivity of the materials, 𝐶 is the specific heat, 𝐷 is the density of the materials, and j is the current density amplitude of the applied electropulse. Although the thermal effect causes changes in microstructure and properties As detailed in [39], this temperature rise, denoted as ∆T m , is governed by the following relationship:…”

Section: Microstructure and Grain Boundaries (Gbs) Evolutionmentioning

confidence: 99%

Elimination of Low-Angle Grain Boundary Networks in FeCrAl Alloys with the Electron Wind Force at a Low Temperature

Rahman,

Todaro,

Warner

et al. 2024

Metals

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Low-angle grain boundaries (LAGBs) accommodate residual stress through the rearrangement and accumulation of dislocations during cold rolling. This study presents an electron wind force-based annealing approach to recover cold-rolling induced residual stress in FeCrAl alloy below 100 °C in 1 min. This is significantly lower than conventional thermal annealing, which typically requires temperatures around 750 °C for about 1.5 h. A key feature of our approach is the athermal electron wind force effect, which promotes dislocation movement and stress relief at significantly lower temperatures. The electron backscattered diffraction (EBSD) analysis reveals that the concentration of low-angle grain boundaries (LAGBs) is reduced from 82.4% in the cold-rolled state to a mere 47.5% following electropulsing. This level of defect recovery even surpasses the pristine material’s initial state, which exhibited 54.8% LAGBs. This reduction in LAGB concentration was complemented by kernel average misorientation (KAM) maps and X-ray diffraction (XRD) Full Width at Half Maximum (FWHM) measurements, which further validated the microstructural enhancements. Nanoindentation tests revealed a slight increase in hardness despite the reduction in dislocation density, suggesting a balance between grain boundary refinement and dislocation dynamics. This proposed low-temperature technique, driven by athermal electron wind forces, presents a promising avenue for residual stress mitigation while minimizing undesirable thermal effects, paving the way for advancements in various material processing applications.

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“…As shown in Figure 11A, Wang et al [157] illustrated that with the prolongation of the high-density multiple pulse treatment (HMPT) time, the high-density dislocation cells and some entanglements disappeared, and the subcrystals preferentially merged through dislocation climbing in the localized regions with a high dislocation density. The majority of equiaxed recrystallized structures exhibit a flattened grain boundary morphology, as depicted in Figure 11A(e).…”

Section: Effects On Recrystallizationmentioning

confidence: 99%

Mechanism of Electropulsing Treatment Technology for Flow Stress of Metal Material: A Review

Lu,

Tang,

et al. 2024

Alloys

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Residual stress is caused by non–uniform deformation caused by non–uniform force, heat and composition, which is of great significance in engineering applications. It is assumed that the residual stress is always the upper limit of the elastic limit, so the reduction of the flow stress will reduce the residual elastic stress. It is particularly important to control the flow stress in metal materials. Compared with traditional methods, the use of electropulsing treatment (EPT) technology stands out due to its energy–efficient, highly effective, straightforward and pollution–free characteristics. However, there are different opinions about the mechanism of reducing flow stress through EPT due to the conflation of the effects from pulsed currents. Herein, a clear correlation is identified between induced stress levels and the application of pulsed electrical current. It was found that the decrease in flow stress is positively correlated with the current density and the duration of electrical contact and current action time. We first systematically and comprehensively summarize the influence mechanisms of EPT on dislocations, phase, textures and recrystallization. An analysis of Joule heating, electron wind effect, and thermal–induced stress within metal frameworks under the influence of pulsed currents was conducted. And the distribution of electric, thermal and stress fields under EPT are discussed in detail based on a finite element simulation (FES). Finally, some new insights into the issues and challenges of flow stress drops caused by EPT are proposed, which is critically important for advancing related mechanism research and the revision of theories and models.

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The coupling of thermal and athermal effect in high-density multiple pulse continuous treatment of AZ31

Cited by 13 publications

References 34 publications

Room temperature control of grain orientation via directionally modulated current pulses

Room temperature control of grain orientation via directionally modulated current pulses

Elimination of Low-Angle Grain Boundary Networks in FeCrAl Alloys with the Electron Wind Force at a Low Temperature

Mechanism of Electropulsing Treatment Technology for Flow Stress of Metal Material: A Review

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