The Developments of Cold-rolled TRIP-assisted Multiphase Steels. Al-alloyed TRIP-assisted Multiphase Steels.

Jacques, Pascal; Girault, Etienne; Mertens, Anne; Verlinden, Bart; Humbeeck, Jan Van; Delannay, Francis

doi:10.2355/isijinternational.41.1068

Cited by 160 publications

(109 citation statements)

References 15 publications

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“…These results are consistent with the observations by Jacques et al [6] that low-Si steel with a low initial content of retained austenite (~3%) displaying a significant elongation of ~20%. Therefore, for a more precise description of the microstructure-properties relation in TRIP-assisted steels, it is very important to know the microstructural features that influence the transformation behavior of retained austenite grains during deformation.…”

Section: Introductionsupporting

confidence: 83%

Deformation-induced austenite grain rotation and transformation in TRIP-assisted steel

et al. 2012

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Uniaxial straining experiments were performed on a rolled and annealed Si-alloyed TRIP (transformation-induced plasticity) steel sheet in order to assess the role of its microstructure on the mechanical stability of austenite grains with respect to martensitic transformation. The transformation behavior of individual metastable austenite grains was studied both at the surface and inside the bulk of the material using electron back-scattered diffraction (EBSD) and X-ray diffraction (XRD) by deforming the samples to different strain levels up to about 20%. A comparison of XRD-and EBSD-results revealed that the retained austenite grains at the surface have a stronger tendency to transform than the austenite grains in the bulk of the material.The deformation-induced changes of individual austenite grains before and after straining were monitored with EBSD. Three different types of austenite grains can be distinguished that have different transformation behaviors: austenite grains at the grain boundaries between ferrite grains, twinned austenite grains, and embedded austenite grains that are completely surrounded by a single ferrite grain. It was found that twinned austenite grains and the austenite grains present at the grain boundaries between larger ferrite grains typically transform first, i.e. are less stable, in contrast to austenite grains that are completely embedded in a larger ferrite grain. In the latter case, straining leads to rotations of the harder austenite grain within the softer ferrite matrix before the austenite transforms into martensite. The analysis suggests that austenite grain rotation behavior is also a significant contributing factor for enhancement of the ductility.

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Section: Introductionsupporting

confidence: 83%

Deformation-induced austenite grain rotation and transformation in TRIP-assisted steel

et al. 2012

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“…21,[27][28][29][30] The 200 C microstructures, with low fractions and lowest stability of the austenite (high M d temperatures), rapidly transform at very small strains. As a result, there is little benefit of the strain induced transformation.…”

Section: Discussionmentioning

confidence: 99%

“…Both temperatures depend on the retained austenite chemical composition. Elements such as C, Mn, Si and Al 21,22) significantly affect the mechanical stability of austenite by decreasing M d and/or M S . Among them C is the element that exhibit the strongest influence.…”

Section: Microstructural Characterizationmentioning

confidence: 99%

The Role of Retained Austenite on Tensile Properties of Steels with Bainitic Microstructures

García‐Mateo¹,

Caballero²

2005

Mater. Trans.

213

103

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In high-carbon, silicon-rich steels it is possible to obtain a very fine bainitic microstructure by transformation at low temperatures (200-300 C). This microstructure consists of slender ferrite plates, with thicknesses of several tens of nm, in a matrix of retained austenite. Whereas strength is mainly provided by to the fine scale of the ferrite plates (stronger phase), ductility is mostly controlled by the retained austenite (softer phase). Further improvement in ductility is achieved by strain induced transformation of austenite to martensite, the so called TRIP effect. In order to take full advantage of this effect, the mechanical stability of the austenite, i.e., its capability to transform to martensite under strain, must not be too low nor excessively high.Two main aspects of the mechanical stability of the retained austenite, morphology and chemical composition, have been studied to determine the role that these play on the ductility behaviour of the bainitic steels studied. It is suggested that the chemical composition has the strongest effect on the ductility of these new high strength alloys.

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“…In most of the works, the processing of TRIP steels with niobium is carried out either as cold rolling followed by intercritical annealing [6], or as thermo-mechanical processing with several deformation steps [7]. For thermo-mechanical treatment, the number of deformations, deformation temperatures and sizes are very important factors influencing resulting microstructures and properties.…”

Section: Introductionmentioning

confidence: 99%

High Versatility of Niobium Alloyed AHSS

Kučerová¹,

Opatová²,

Káňa³

et al. 2017

Archives of Metallurgy and Materials

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The effect of processing parameters on the final microstructure and properties of advanced high strength CMnSiNb steel was investigated. Several processing strategies with various numbers of deformation steps and various cooling schedules were carried out, namely heat treatment without deformation, conventional quenching and TRIP steel processing with bainitic hold or continuous cooling. Obtained multiphase microstructures consisted of the mixture of ferrite, bainite, retained austenite and M-A constituent. They possessed ultimate tensile strength in the range of 780-970 MPa with high ductility A 5 mm above 30%. Volume fraction of retained austenite was for all the samples around 13%. The only exception was reference quenched sample with the highest strength 1186 MPa, lowest ductility A 5 mm = 20% and only 4% of retained austenite.

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The Developments of Cold-rolled TRIP-assisted Multiphase Steels. Al-alloyed TRIP-assisted Multiphase Steels.

Cited by 160 publications

References 15 publications

Deformation-induced austenite grain rotation and transformation in TRIP-assisted steel

Deformation-induced austenite grain rotation and transformation in TRIP-assisted steel

The Role of Retained Austenite on Tensile Properties of Steels with Bainitic Microstructures

High Versatility of Niobium Alloyed AHSS

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