A novel technique for developing bimodal grain size distributions in low carbon steels

Azizi-Alizamini, Hamid; Militzer, Matthias; Poole, Warren J.

doi:10.1016/j.scriptamat.2007.08.035

Cited by 122 publications

(63 citation statements)

References 19 publications

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“…The mechanical properties obtained by short annealing time at high temperature are comparable to the results reported by Azizi-Alizamini et al. 16) They used a novel process for fabrication of the UFG low carbon steel containing 0.17% C with bimodal grain size distribution. In their proposed process, a ferritic microstructure with bimodal ferrite grain size distribution was fabricated by 50% cold rolling and subsequent annealing of a ferrite-martensite dual-phase microstructure.…”

Section: Mechanical Propertiessupporting

confidence: 83%

Effect of Process Parameters on Microstructures and Mechanical Properties of a Nano/ultrafine Grained Low Carbon Steel Produced by Martensite Treatment Using Plane Strain Compression

et al. 2012

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In this work, the martensite treatment consisting of cold deformation by plane strain compression and subsequent annealing was used for producing the nano/ultrafine grained structure in a low carbon steel. The equivalent strain was varied from 0.1 to 2, while the annealing process was carried out in the temperature range of 400-600°C for 0-180 min. The microstructural evolution and mechanical properties of the as-deformed and annealed specimens were investigated. The results showed that in the as-deformed specimens, increase in strain intensified the volume fraction of the martensite cell blocks and consequently the strength. Fully equiaxed nano/ultrafine grained ferrite was developed from the martensite cell blocks during the annealing at warm temperature around 500°C for sufficient time lengths. It was concluded that the final multi-phased microstructure composed of ultrafine ferrite grains, block-tempered martensite, and fine cementite precipitates was responsible for the obtained superior mechanical properties.

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Section: Mechanical Propertiessupporting

confidence: 83%

Effect of Process Parameters on Microstructures and Mechanical Properties of a Nano/ultrafine Grained Low Carbon Steel Produced by Martensite Treatment Using Plane Strain Compression

et al. 2012

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“…To this end, a vast variety of microstructure variations can be introduced in DP steels by small changes in the composition and/or thermomechanical processing [18,[35][36][37][38][39][40][41][42]. To guide this microstructure design process, micromechanicsbased foundations and design guidelines are needed that would ensure damage-prone microstructures.…”

Section: Introductionmentioning

confidence: 99%

Retardation of plastic instability via damage-enabled microstrain delocalization

et al. 2015

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Multi-phase microstructures with high mechanical contrast phases are prone to microscopic damage mechanisms. For ferrite-martensite dual-phase steel, for example, damage mechanisms such as martensite cracking or martensite-ferrite decohesion are activated with deformation, and discussed often in literature in relation to their detrimental role in triggering early failure in specific dualphase steel grades. However, both the micromechanical processes involved and their direct influence on the macroscopic behavior are quite complex, and a deeper understanding thereof requires systematic analyses. To this end, an experimental-theoretical approach is employed here, focusing on three model dual-phase steel microstructures each deformed in three different strain paths. The micromechanical role of the observed damage mechanisms is investigated in detail by in-situ scanning electron microscopy tests, quantitative damage analyses, and finite element simulations. The comparative analysis reveals the unforeseen conclusion that damage nucleation may have a beneficial mechanical effect in ideally designed dual-phase steel microstructures (with effective crack-arrest mechanisms) through microscopic strain delocalization.

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“…1) However, most of these UFG ferrite/cementite steels are characterized by a very low strain hardening rate and consequently, a low uniform elongation, when compared to their coarse grained counterparts. 2,3) Among the different attempts to restore the strain hardening capacity of UFG steels, [4][5][6] the replacement of cementite by martensite through an intercritical annealing treatment seems to be most efficient. 7,8) During intercritical annealing in the ferrite + austenite two-phase field, the desired amount of austenite is formed.…”

Section: Introductionmentioning

confidence: 99%

Microstructure Control during Fabrication of Ultrafine Grained Dual-phase Steel: Characterization and Effect of Intercritical Annealing Parameters

2012

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An ultrafine grained (UFG) ferrite/cementite steel was subjected to intercritical annealing in order to obtain an UFG ferrite/martensite dual-phase (DP) steel. The intercritical annealing parameters, namely, holding temperature and time, heating rate, and cooling rate were varied independently by applying dilatometer experiments. Microstructure characterization was performed using scanning electron microscopy (SEM) and high-resolution electron backscatter diffraction (EBSD). An EBSD data post-processing routine is proposed that allows precise distinction between the ferrite and the martensite phase. The sensitivity of the microstructure to the different annealing conditions is identified. As in conventional DP steels, the martensite fraction and the ferrite grain size increase with intercritical annealing time and temperature. Furthermore, the variations of the microstructure are explained in terms of the changes in phase transformation kinetics due to grain refinement and the manganese enrichment in cementite during warm deformation.

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A novel technique for developing bimodal grain size distributions in low carbon steels

Cited by 122 publications

References 19 publications

Effect of Process Parameters on Microstructures and Mechanical Properties of a Nano/ultrafine Grained Low Carbon Steel Produced by Martensite Treatment Using Plane Strain Compression

Effect of Process Parameters on Microstructures and Mechanical Properties of a Nano/ultrafine Grained Low Carbon Steel Produced by Martensite Treatment Using Plane Strain Compression

Retardation of plastic instability via damage-enabled microstrain delocalization

Microstructure Control during Fabrication of Ultrafine Grained Dual-phase Steel: Characterization and Effect of Intercritical Annealing Parameters

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