Effect of banding on micro-mechanisms of damage initiation in bainitic/martensitic steels

Shakerifard, Behnam; Lopez, Jesus Galan; Hisker, F.; Kestens, Léo

doi:10.1016/j.msea.2018.08.049

Cited by 8 publications

(6 citation statements)

References 31 publications

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“…Voids are distributed heterogeneously and more densely present in the vicinity of the fracture surface. The microstructural observation of the interrupted tensile sample at the elongation of 5%, reported elsewhere by Shakerifard et al [18], confirmed the absence of void formation during the uniform plastic deformation. In contrast to this bainitic martensitic steel, for ferritic and martensitic dual phase (DP) steels, it has been reported that voids can nucleate in the early stage of plastic deformation prior to necking [29].…”

Section: Quantitative Analysis Of Voids' Evolutionsupporting

confidence: 84%

“…at the microstructure level, these local deformation incompatibilities may induce void formation at the critical moment in order to dissipate the local plastic work. The role of the second phase (i.e., martensite) and its morphology (size, shape, and distribution) in ductile damage initiation in dual phase steels has been extensively studied by advanced experimental and crystal plasticity-based modelling techniques [14][15][16][17][18]. Moreover, in polycrystalline materials, the anisotropic response of each individual crystallographic orientation to stress (and/or strain) is another important factor that needs to be considered in damage initiation mechanisms.…”

Section: Methodsmentioning

confidence: 99%

“…The investigated steel consists of a bainitic matrix with two main second phase constituents of martensite and carbide. However, two types of martensites are observed: (i) auto-tempered martensite (ATM) and (ii) MA islands, which are composed of isolated martensite blocks (M) with a negligible fraction of retained austenite (A) between the martensite laths [18]. The EBSD technique is employed to quantify the grain size and fraction of bainite and martensite (ATM and MA) separately.…”

Section: Methodsmentioning

confidence: 99%

“…This enables to understand at which macroscopic strain level damage initiates in the microstructure. In this research work, particular attention is given to the crystallographic orientation aspect of damage initiation, while the mechanical phase contrast and its morphological aspect is reported elsewhere by Shakerifard et al [18]. An EBSD analysis is employed to observe the orientations around the initiated voids.…”

Section: Introductionmentioning

confidence: 99%

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A New Electron Backscatter Diffraction-Based Method to Study the Role of Crystallographic Orientation in Ductile Damage Initiation

Shakerifard

Lopez

Kestens

2020

Metals

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The third generation of advanced high strength steels shows promising properties for automotive applications. The macroscopic mechanical response of this generation can be further improved by a better understanding of failure mechanisms on the microstructural level and micro-mechanical behavior under various loading conditions. In the current study, the microstructure of a multiphase low silicon bainitic steel is characterized with a scanning electron microscope (SEM) equipped with an electron backscatter diffraction detector. A uniaxial tensile test is carried out on the bainitic steel with martensite and carbides as second phase constituents. An extensive image processing on SEM micrographs is conducted in order to quantify the void evolution during plastic deformation. Later, a new post-mortem electron backscatter diffraction-based method is introduced to address the correlation between crystallographic orientation and damage initiation. In this multiphase steel, particular crystallographic orientation components were observed to be highly susceptible to micro-void formation. It is shown that stress concentration around voids is rather relaxed by void growth than local plasticity. Therefore, this post-mortem method can be used as a validation tool together with a crystal plasticity-based hardening model in order to predict the susceptible crystallographic orientations to damage nucleation.

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Section: Quantitative Analysis Of Voids' Evolutionsupporting

confidence: 84%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A New Electron Backscatter Diffraction-Based Method to Study the Role of Crystallographic Orientation in Ductile Damage Initiation

Shakerifard

Lopez

Kestens

2020

Metals

Self Cite

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“…Steels with the martensite-bainite composite structure are expected to be used as high-strength steels. 10,11) Generally, the microstructure of a type of steel changes when its elemental contents are changed. Therefore, the complexing nature of the microstructure in case of BDT remains ambiguous, especially the controlling factors of BDT.…”

Section: Brittle-to-ductile Transition In Martensite -Bainite Steelmentioning

confidence: 99%

Brittle-to-ductile Transition in Martensite – Bainite Steel

et al. 2021

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To understand the effect of composite structure on brittle-to-ductile transition (BDT) in low-carbon martensite-bainite steel, this study investigates the temperature dependence of the impact absorbed energy in five types of steel having the same chemical composition: fully martensitic steel, fully bainitic steel, and martensite-bainite steel with bainite fractions of 4%, 15%, and 55%, respectively. The BDT temperature was the highest for fully martensitic steel, followed by those of the martensite-4% bainite, martensite-15% bainite, martensite-55% bainite, and full bainitic steel. The BDT temperatures of martensite-15% bainite, martensite-55% bainite, and fully bainitic steel were close despite the large differences in their bainite volume fractions, suggesting that the trend of BDT temperatures cannot be explained simply based on the rule of mixture. The temperature dependence of 0.2% proof stress was measured in each steel to understand the trend of BDT temperature based on the shielding theory. Optical micrographs and the temperature dependence of effective stress indicated that the dislocations in bainite were preferentially activated and governed the yielding and BDT in the martensite-barite steels. This phenomenon was also linked to the network structures of bainite surrounding the martensite, where bainite was subjected to plastic deformation immediately after yielding in the employed steel.

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