On the Mn–C Short-Range Ordering in a High-Strength High-Ductility Steel: Small Angle Neutron Scattering and Ab Initio Investigation

Song, Wenwen; Bogdanovski, Dimitri; Yildiz, Ahmet Bahadir; Houston, Judith E.; Dronskowski, Richard; Bleck, Wolfgang

doi:10.3390/met8010044

Cited by 20 publications

(8 citation statements)

References 66 publications

(91 reference statements)

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“…Al delays the reorientation of Mn-C point defect complexes by rising the process activation energy [28,[31][32][33][34]. Song et al [35] and Madivala et al [36] reported that some amount of Al addition could suppress the Mn-C formation in high-Mn steels. This might be the reason for the delay or absence of the serration phenomenon in Al-alloyed high-Mn steels.…”

Section: Theories Explaining the Plc Mechanism In Medium-and High-manmentioning

confidence: 99%

Explanation of the PLC Effect in Advanced High-Strength Medium-Mn Steels. A Review

et al. 2019

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The paper reviews the recent works concerning the Portevin-Le Chatelier (PLC) effect in Advanced High-Strength Steels (AHSSs) with a special attention to high-strength medium-manganese steels. Theories explaining the mechanism of the plastic instability phenomenon in steels with medium-and high-Mn contents were discussed. The relationships between microstructural effects such as TRIP (Transformation-Induced Plasticity), TWIP (Twinning-Induced Plasticity) and the PLC effect were characterized. The effects of processing conditions including a deformation state (hot-rolled and cold-rolled) and strain parameters (deformation temperature, strain rate) were addressed. Factors affecting the value of critical strain for the activation of serrated flow behavior in particular in medium-manganese steels were described.The explanation of the Portevin-Le Chatelier mechanism in medium-Mn steels showing the TRIP effect is a complicated issue because of their microstructure consisting of several phases, as well as the TRIP effect exhibited by these steels. The exact characteristics of the factors affecting the PLC effect in AHSS is very important, both from a research point of view and their industrial implementation. This overview concerns the PLC phenomenon in Advanced High Strength Steels (AHSSs), with particular emphasis on advanced medium-Mn TRIP steels. The Nature of PLC Effect in SteelsThe plastic instability phenomenon occurring during the deformation of metallic materials shows two most common forms of propagative bands: Lüders and Portevin-Le Chatelier bands. The Lüders bands refer to the regions of localized strain. They form immediately after the onset of plastic deformation from the yield point drop, followed to a dominant stage of the stress plateau stage. Lüders bands are commonly caused by static strain aging (SSA) [13]. Static strain aging is characterized by an increase in strength properties associated with a decrease in plasticity. The PLC bands are represented by characteristic serrations on stress-strain curves. PLC bands are usually related to the dynamic strain aging (DSA) effect. The occurrence of the PLC bands is much more erratic, and can be observed in various forms (serration types) in comparison to the Lüders bands.There are several theories which explain the PLC effect in metallic materials. However, none has been so far clearly confirmed. The first interpretation of this phenomenon was proposed by Cottrell [1]. From his point of view, the PLC effect is related to the interactions between solute atoms, such as C or N, and mobile dislocations. The presence of serrations on a tensile curve is associated with the rapid release of dislocations from the atmospheres of dissolved atoms, which block their movement. This model is based on the assumption that atmospheres are formed around dislocations due to volume diffusion. In the presence of substitution atoms, diffusion is facilitated by vacancies resulting from plastic deformation. The interstitial gaps located in the vicinity of the dislocation are enl...

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Section: Theories Explaining the Plc Mechanism In Medium-and High-manmentioning

confidence: 99%

Explanation of the PLC Effect in Advanced High-Strength Medium-Mn Steels. A Review

et al. 2019

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“…This is in agreement with some authors, stating ordering as the origin of strain aging in high‐manganese steels. [ 12,33,49 ] Others, assume cluster formation is impossible, as they state the time needed to form C–Mn clusters is up to 10 27 s. [ 57 ] A combined effect is stated to increase planar slip due to short‐range ordering and thus increase twinning, which would as well explain the stronger localization [ 37,58,59 ] as twinning promotes a serrated flow. [ 20,60,61 ] Other investigations even show that not only does a higher pre‐deformation intensifies strain aging, but also an increase in temperature or a higher strain rate during pre‐deformation further accelerates the static strain aging process.…”

Section: Discussionmentioning

confidence: 99%

Dynamic and Static Strain Aging in a High‐Manganese Steel

Wesselmecking

Song

Bleck

2022

steel research int.

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Carbon‐containing high‐manganese steels are susceptible to strain aging, which influences the mechanical properties during and after deformation. To understand the strain aging behavior of austenitic Fe‐22Mn‐1.3Al‐0.3C high‐manganese steel, dynamic as well as static strain aging are examined. Dynamic strain aging, occurring during deformation, is quantified by tensile tests at different strain rates. The strain localization during straining is analyzed by digital image correlation. A decrease in strain rate increases the tensile strength and influences the onset of a serrated flow. Static strain aging is quantified by interrupted tensile tests, combined with digital image correlation and small‐angle neutron scattering (SANS). The yield strength increases due to static strain aging at room temperature within the period of days. The samples show extended yield point (yield point elongation) and the effect strengthens at higher pre‐deformation. With SANS, evidence of carbon‐manganese ordering (C–Mn ordering) during aging is obtained and correlated.

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“…Such sustained and high work hardening rates can also be seen in austenitic steels with high C content because of DSA [41]. The ab-initio based study combined with SANS experiments by Song et al [42] and SANS experimental study by Kang et al proved the presence of Mn-C octahedral clusters and their evolution, indicating the occurrence of DSA during deformation in high Mn steels. The occurrence of static strain aging due to the presence of Mn-C SRO was stated to be responsible for increased yield strength and pronounced yielding of annealed TWIP steel [43].…”

Section: Strain Hardening and Twinning Evolutionmentioning

confidence: 94%

Strain Hardening, Damage and Fracture Behavior of Al-Added High Mn TWIP Steels

Madivala

Schwedt

Prahl

et al. 2019

Metals

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The strain hardening and damage behavior of Al-added twinning induced plasticity (TWIP) steels were investigated. The study was focused on comparing two different alloying concepts by varying C and Mn contents with stacking fault energy (SFE) values of 24 mJ/m 2 and 29 mJ/m 2 . The evolution of microstructure, deformation mechanisms and micro-cracks development with increasing deformation was analyzed. Al-addition has led to the decrease of C diffusivity and reduction in tendency for Mn-C short-range ordering resulting in the suppression of serrated flow caused due to dynamic strain aging (DSA) in an alloy with 0.3 wt.% C at room temperature and quasi-static testing, while DSA was delayed in an alloy with 0.6 wt.% C. However, an alloy with 0.6 wt.% C showing DSA effect exhibited enhanced strain hardening and ductility compared to an alloy with 0.3 wt.% C without DSA effect. Twinning was identified as the most predominant deformation mode in both the alloys, which occurred along with dislocation glide. Al-addition has increased SFE thereby delaying the nucleation of deformation twins and prolonged saturation of twinning, which resulted in micro-cracks initiation only just prior to necking or failure. The increased stress concentration caused by the interception of deformation twins or slip bands at grain boundaries (GB) has led to the development of micro-cracks mainly at GB and triple junctions. Deformation twins and slip bands played a vital role in assisting inter-granular crack initiation and propagation. Micro-cracks that developed at manganese sulfide and aluminum nitride inclusions showed no tendency for growth even after large deformation indicating the minimal detrimental effect on the tensile properties.

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On the Mn–C Short-Range Ordering in a High-Strength High-Ductility Steel: Small Angle Neutron Scattering and Ab Initio Investigation

Cited by 20 publications

References 66 publications

Explanation of the PLC Effect in Advanced High-Strength Medium-Mn Steels. A Review

Explanation of the PLC Effect in Advanced High-Strength Medium-Mn Steels. A Review

Dynamic and Static Strain Aging in a High‐Manganese Steel

Strain Hardening, Damage and Fracture Behavior of Al-Added High Mn TWIP Steels

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