Microstructure of titanium on complex deformation paths: Comparison of ECAP, KOBO and HE techniques

Kawałko, Jakub; Wroński, M.; Bieda, M.; Sztwiertnia, K.; Wierzbanowski, K.; Wojtas, Daniel; Łagoda, М.; Ostachowski, Paweł; Pachla, W.; Kulczyk, Mariusz

doi:10.1016/j.matchar.2018.04.037

Cited by 24 publications

(14 citation statements)

References 43 publications

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“…The agreement of the estimates of θ 1 and θ 2 for the samples deformed to ε = 1 (Figs. 3a, b) with TEM results on IDBs and GNBs [5,8,12] confirms that representation of the lower angle part of DIB distribution as a sum of two partial distributions corresponding to IDBs and GNBs is plausible.…”

Section: Resultssupporting

confidence: 65%

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Misorientation distribution of high angle boundaries formed by grain fragmentation: EBSD-based characterization and analysis performed on heavily deformed iron

Zolotorevsky¹,

Рыбин²,

Matvienko³

et al. 2018

LoM

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When studying crystal lattice fragmentation during plastic deformation of metals, it is of great importance to have qualitative characteristics of high angle deformation-induced boundaries since their formation and evolution control grain refinement. It is challenging, however, to separate the contribution of deformation-induced boundaries (DIBs) to overall misorientation distribution from the contribution of original grain boundaries, particularly when total lengths of high-angle deformationinduced and original grain boundaries are comparable. The present study suggests a method making this separation possible basing on electron backscattering diffraction (EBSD) and uses the method to characterize the evolution of DIB misorientations in polycrystalline iron deformed under various conditions. The method provides a reasonable accuracy up to the strain of about 2 in the case of uniaxial compression and up to the strain of 5 in the case of biaxial forging. It has been shown that the character of evolution of DIBs in iron changes weakly when the deformation temperature increases from the room one to 400°C. At the same time, the evolution differs significantly in iron deformed by uniaxial compression and biaxial forging. In all cases considered in the present study the misorientation distribution of DIBs can be represented as a superposition of three partial distributions. The first two partial distributions correlate with those obtained earlier in transmission electron microscopic studies. The third one suggested in the present study describes the highest-angle part of misorientation distribution of DIBs. Each partial distribution evolves according to its own law in the process of deformation.

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Section: Resultssupporting

confidence: 65%

“…3 demonstrates some examples of the analysis. Note that, according to TEM [5,8], IDB misorientations increase so slowly with deformation that the average angle θ 1 reaches the level of ~ 2° only at ε > 1. Thus, when using a threshold angle of 2°, about one half of IDBs is ignored in the EBSD analysis.…”

Section: Resultsmentioning

confidence: 97%

Misorientation distribution of high angle boundaries formed by grain fragmentation: EBSD-based characterization and analysis performed on heavily deformed iron

Zolotorevsky¹,

Рыбин²,

Matvienko³

et al. 2018

LoM

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“…The (101 ̅ 0) prismatic planes formed several maxima in the peripheral region: one perpendicular to the axial direction and then two which were ~60° inclined from the axial direction of the sample. This so-called partial fiber texture is typical for extruded hexagonal materials [27,28]. In the central region (b), the texture was completely different.…”

Section: Microstructure: Ebsd Resultsmentioning

confidence: 89%

Characterization of the Microstructure, Local Macro-Texture and Residual Stress Field of Commercially Pure Titanium Grade 2 Prepared by CONFORM ECAP

Németh

Horváth

Hervoches

et al. 2018

Metals

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The paper investigated the residual strain and stress distribution, microstructure, and macro-texture along the transverse direction of commercially pure titanium grade 2 samples prepared by the CONFORM ECAP technique. This method belongs to the severe plastic deformation methods; hence, it could be assumed that residual stress fields would be present in the work-pieces. Residual stresses cannot be directly measured; thus, neutron diffraction measurements, Electron back-scatter diffraction (EBSD) investigations, and local X-ray macro-texture measurements were performed in different regions of the sample to determine the data for the residual stress calculation. The calculation was based on the modified Kröner model. Neutron diffraction strain scans and residual stress calculations revealed that symmetrical residual strain and stress gradients with compression character were present in the axial and hoop direction after one and two passes. Asymmetric distribution of the residual strains and stresses remained after the third pass of the CONFORM ECAP. EBSD investigations showed that after the first pass, significant grain refinement occurred; however, further passes did not cause any dramatic grain refinement. X-ray texture measurements revealed that local macro-texture was dependent on the number of passes of the CONFORM ECAP and on the investigated area in the samples.

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“…This suggests that the microstructure of Zn-1Mg alloy obtained during the multi-pass hydrostatic extrusion process is a result of continuous dynamic recrystallization (cDRX), which is typically responsible for the grain refinement of the materials with a high stacking fault energy subjected to SPD techniques. [36] Moreover, based on analysis of the Zn-1Mg alloy performed on LCS, a bimodal microstructure typical for other HCP metals [37,38] was observed during the first stages of plastic deformation via hydrostatic extrusion. New grains grew at the boundaries of primary large grains.…”

Section: Discussionmentioning

confidence: 95%

Controlled Grain Refinement of Biodegradable Zn-Mg Alloy: The Effect of Magnesium Alloying and Multi-Pass Hydrostatic Extrusion Preceded by Hot Extrusion

Jarzębska

Bieda

Maj

et al. 2020

Metall Mater Trans A

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To satisfy the most stringent criteria in terms of new cardiovascular stents, pure Zn was alloyed with 1 wt pct of Mg and subsequently subjected to plastic deformation, using conventional hot extrusion followed by multi-pass hydrostatic extrusion. A detailed microstructural and textural characterization of the obtained materials was conducted, and mechanical properties were assessed at each pass of deformation process. In contrast to pure Zn, hydrostatically extruded low-alloyed Zn is characterized by a remarkable increase in strength and ductility (YS = 383 MPa, E = 23 pct), exceeding the values needed for stents. Such behavior is associated with a dual microstructure containing fine-grained Zn, alternatively arranged with bands of a fragmented eutectic. Extensive grain refinement was achieved due to the process of continuous dynamic recrystallization. Hydrostatic extrusion changes the initial $$ \langle 10\bar{1}0\rangle $$ ⟨ 10 1 ¯ 0 ⟩ fiber texture to a 〈0002〉 and $$ \langle 10\bar{1}1\rangle $$ ⟨ 10 1 ¯ 1 ⟩ double fiber texture in which the 〈0002〉 component decreases with each pass of hydrostatic extrusion. The gradual evolution of texture components was simulated using a visco-plastic self-consistent model, which confirmed that, during hydrostatic extrusion, secondary slip systems were activated involving mostly the pyramidal one.

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Microstructure of titanium on complex deformation paths: Comparison of ECAP, KOBO and HE techniques

Cited by 24 publications

References 43 publications

Misorientation distribution of high angle boundaries formed by grain fragmentation: EBSD-based characterization and analysis performed on heavily deformed iron

Misorientation distribution of high angle boundaries formed by grain fragmentation: EBSD-based characterization and analysis performed on heavily deformed iron

Characterization of the Microstructure, Local Macro-Texture and Residual Stress Field of Commercially Pure Titanium Grade 2 Prepared by CONFORM ECAP

Controlled Grain Refinement of Biodegradable Zn-Mg Alloy: The Effect of Magnesium Alloying and Multi-Pass Hydrostatic Extrusion Preceded by Hot Extrusion

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