Thermal stability of ARMCO iron processed by ECAP

Serrano-Muñoz, Jordi; Higuera, Oscar Fabián; Expósito, Ana Hernández; Boulaajaj, A.; Bolmaro, R.E.; Dumitru, Florina; Calvillo, Pablo Rodríguez; Jorge, Alberto Moreira; Cabrera, J.M.

doi:10.1007/s00170-018-2353-7

Cited by 19 publications

(11 citation statements)

References 52 publications

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“…Reconstruction of subgrains and grains was performed by the following boundary conditions: subgrains were assumed to be bounded by mainly low-angle boundaries (LAGBs) 2 • ≤ ω ≤ 15 • , and occasionally also by some high-angle boundaries (HAGBs) ω ≥ 15 • , whereas grains should be only bounded by HAGBs. The GND density, ρ was estimated from the EBSD data as proposed by Hughes and Hansen [25] and previously used in similar studies [26,27,28]:…”

Section: Ebsdmentioning

confidence: 99%

A multi-scale study of the interaction of Sn solutes with dislocations during static recovery in α-Fe

et al. 2019

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The properties of engineering materials can be improved by optimising the microstructural developments during annealing processes. Here, we investigate the effect of Sn on the recovery annealing of cold rolled Fe-3%Si alloys. We use a multiscale approach combining micro hardness, electron back scattering diffraction (EBSD), and dark field X-ray microscopy (DFXM): a recent, nondestructive synchrotron-based technique that allows 3D mapping of orientation and lattice strain within individual grains embedded in bulk samples. Micro hardness results show that the Sn solute has a strong effect on the recovery kinetics. These results are compared to a physical kinetic model suggesting that Sn limits the softening. This observation is further discussed by a complementary atomistic modelling that demonstrates solute-dislocation interaction around edge dislocations. In situ DFXM experiments reveal the 3D microstructural evolution upon annealing at the grain level with high angular resolution. The DFXM observations show that Sn slows the recovery kinetics within individual grains, in agreement with the other microscopic investigations. Furthermore, the DFXM results provide a direct observation of strain fields around dislocation loops in an embedded single grain, which is argued to remain static due to solute effect during recovery.

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Section: Ebsdmentioning

confidence: 99%

A multi-scale study of the interaction of Sn solutes with dislocations during static recovery in α-Fe

et al. 2019

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“…This GND saturation reflects that the ECAP process has reached its lower limit for the grain size reduction in this alloy. Muñoz et al [ 53 ] mentioned that the high GNDs in UFG materials measure the capacity to reach smaller grain sizes. In this way, high GND gives rise to grains subdivision that helps to compensate for the curvature induced by the SPD.…”

Section: Resultsmentioning

confidence: 99%

Strain‐Hardening Behavior in an AA6060‐T6 Alloy Processed by Equal Channel Angular Pressing

Khelfa

Muñoz-Bolaños

et al. 2020

Adv Eng Mater

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Strain hardening is a useful mechanism for improving mechanical properties in materials. This study investigates the strain‐hardening behavior of an AA6060 alloy processed by equal channel angular pressing (ECAP) up to 12 passes. Analysis by electron backscattered diffraction (EBSD) shows that the average geometrically necessary dislocations (GNDs) density increases continually up to the fourth pass and then saturates at a value of ≈1.85 × 1014 m−2. Hollomon and Kocks–Mecking–Estrin (KME) analysis are used to investigate the strain‐hardening behavior of the resulting ultrafine‐grained alloy. Results indicate that the strain‐hardening capacity (HC) and the strain‐hardening exponent (n) of all deformed specimens are lower in comparison with the as‐received condition. Moreover, the strain‐hardening rate fluctuates with the ECAP passes. First, it increases from the first ECAP pass up to the fourth pass, then diminishes up to the fifth pass, and finally, it increases again with further deformation. The difference in the strain‐hardening behavior of the ECAPed AA6060 is examined in terms of the grain size effect. It is shown that the strain‐hardening curves change notably with diminishing the grain size. In addition, the KME model is used to depict the storage and annihilation of dislocations in the ECAPed specimens.

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“…To clarify if the current data fit the expected trend from the Hall-Petch relationship for iron, the current results are plotted as a function of the inverse of the square root of the grain size in Figure 9. Data from the literature [11,[20][21][22] are also shown considering the flow stress as the hardness divided by 3. [23] The grain size of the as-processed material was estimated as d % 200 nm from the literature.…”

Section: Discussionmentioning

confidence: 99%

Corrosion in Hank's Solution and Mechanical Strength of Ultrafine‐Grained Pure Iron

et al. 2020

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In recent years, there has been a growing interest in developing biodegradable implants which are absorbed by the body after fulfilling a task. Pure iron is a candidate for such applications because it is considered biocompatible and it does not passivate in physiological media. Herein, the potential to increase the strength of pure iron through grain refinement is evaluated to allow a reduction in size of implants and its effect on corrosion behavior. High‐pressure torsion is applied to process pure iron and to refine the grain size of less than 1 μm. Annealing at different temperatures is used to produce samples with different grain sizes. Compression tests show a significant increase in flow stress to over 1 GPa in samples with very small grain sizes. However, such structure is associated with negligible strain hardening and strain‐rate sensitivity. Electrochemical and immersion tests in Hank's solution show that the grain refinement reduces the corrosion rate significantly. Samples with grain sizes smaller than 1 μm display uniform corrosion and develop a homogeneous surface layer of corrosion products. Thus, severe plastic deformation followed by annealing produces mechanically stronger pure iron with reduced biodegradability.

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Thermal stability of ARMCO iron processed by ECAP

Cited by 19 publications

References 52 publications

A multi-scale study of the interaction of Sn solutes with dislocations during static recovery in α-Fe

A multi-scale study of the interaction of Sn solutes with dislocations during static recovery in α-Fe

Strain‐Hardening Behavior in an AA6060‐T6 Alloy Processed by Equal Channel Angular Pressing

Corrosion in Hank's Solution and Mechanical Strength of Ultrafine‐Grained Pure Iron

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