Warm Formability of Ultra High-Strength Low Alloy TRIP-aided Sheet Steels with Bainitic Ferrite Matrix

Sugimoto, Koh‐ichi; Song, Sung-Moo; Sakaguchi, Jyunya; Nagasaka, Akihiko; Kashima, Takahiro

doi:10.2355/tetsutohagane1955.91.2_278

Cited by 14 publications

(8 citation statements)

References 13 publications

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“…Later on, Sugimoto et al [29] also showed that it was not only martensite which could form under straining, but also bainite, as they detected its formation when performing high temperature tensile tests to dual phase steels. Their research on TRIP effect has been verified by many others [30][31][32][33][34][35][36][37][38][39].…”

Section: Introductionmentioning

confidence: 87%

Stress or strain induced martensitic and bainitic transformations during ausforming processes

2020

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The so-called ausforming treatment consists in plastically deforming a fully austenitized steel below the recrystallization stop temperature, prior to either a martensitic or a bainitic transformation. Although this procedure is envisioned as a way to improve the mechanical response of the attained microstructure, it is not without its drawbacks, as the possibility of phase transformations occurring during the deformation step. When such step is applied at relatively higher temperatures than those of the aimed microstructure, the presence of those softer phases could be rather detrimental for the final microstructure. The current study aims to further study those phase transformations to analyze whether they are induced via either stress or strain and to identify the temperature ranges in which they tend to occur, so that they can be avoided or used to improve the final microstructure properties in the future. A final evaluation on the impact of these induced transformations on the final microstructure when deformation is followed by either cooling or an isothermal treatment is also performed.

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Section: Introductionmentioning

confidence: 87%

Stress or strain induced martensitic and bainitic transformations during ausforming processes

2020

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“…The difference of 0.2 of the proportional constant between the TDP and MDP4 steels is attributed to the occurrence of the strain-induced martensitic transformation (SIMT) 6) of γ R (Figs. 10,11).…”

Section: Effect Of Hardness Distribution In Bending Regionmentioning

confidence: 99%

“…The authors have conducted a lot of research on the deep drawability, 6,[8][9][10] stretch-formability, 10,11) stretch-flangeability [11][12][13][14][15][16] and bendability 14,16) in the low alloy TRIP-aided steels to clarify the effects of the matrix, the second phase (γ R ) morphology, and the γ R characteristics on the press formability. Moreover, it has been reported that the TRIPaided annealed martensitic steels (TAM steels) consisting of annealed martensitic lath matrix and needle-shaped retained austenite, and the TRIP-aided bainitic ferrite steels (TBF steels) with bainitic ferrite lath matrix and film-like γ R exhibited the excellent stretch-flangeability in comparison with the TDP steels with polygonal ferrite matrix and granular γ R as the second phase, 8,10,16) and low-alloy TRIP-aided steels possessed the excellent press formability due to the high volume fraction of γ R and high carbon concentration in γ R .…”

Section: Introductionmentioning

confidence: 99%

Effects of Silicon and Manganese Contents on V-Bending in High-Strength TRIP-Aided Dual-Phase Steel Sheets with Polygonal Ferrite Matrix

et al. 2021

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Effects of silicon and manganese contents on V-bending in high-strength TRIP-aided dual-phase (TDP) steel sheets with polygonal ferrite matrix were investigated for automotive applications. V-bending test was performed on a hydraulic testing machine at a processing speed of 1 mm/min, using a rectangular specimen (50 mm in length, 5 mm in width, 1.2 mm in thickness), 88-degree punch (2.0 mm in punch radius), and 88-degree die (12 mm in die width, 0.8 mm in die radius). The main results are as follows.(1) The 0.2C-(1.0-2.5)Si-(1.0-2.0)Mn, mass% TDP steel sheets were able to perform V-bending by straininduced martensitic transformation of TRIP effect. On the other hand, ferrite-martensite dual-phase (MDP0) steel sheet of 900 MPa grade was not able to perform 90-degree V-bending because of initiation of crack on an outer surface.(2) The 0.2C-2.5Si-1.5Mn, mass% TDP-G steel sheet of 980 MPa grade was able to enable the 90-degree V-bending that considered an amount of springback (Δθ = θ 1 − θ 2 ), in which the θ 1 and the θ 2 are a bending angle on loading and a bending angle after unloading respectively, of more than 2-degree by controlling a displacement of punch bottom dead center.

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“…This type of transformations can happen from the austenite in microstructures in which the austenite is the only phase [5][6][7][8][9][10][11], which are called fully austenitic microstructures, from now on. They can also occur from the retained austenite in microstructures which consist of different phases [1,4,[12][13][14][15][16][17][18][19], which are named multiphase microstructures, from now on. Some examples of multiphase microstructures are microstructures consisting of allotriomorphic ferrite, martensite, bainitic ferrite, and retained austenite [20], bainitic microstructures with retained austenite [21] or microstructures obtained by a quenching and partitioning (Q&P) treatment with retained austenite [22].…”

Section: Introductionmentioning

confidence: 99%

Future Trends on Displacive Stress and Strain Induced Transformations in Steels

Eres-Castellanos

García‐Mateo

Caballero

2021

Metals

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Displacive stress and strain induced transformations are those transformations that occur when the formation of martensite or bainitic ferrite is promoted by the application of stress or strain. These transformations have been shown to be one of the mechanisms by which the mechanical properties of a microstructure can be improved, as they lead to a better ductility and strength by the transformation induced plasticity effect. This review aims to summarize the fundamental knowledge about them, both in fully austenitic or in multiphase structures, pointing out the issues that—according to the authors’ opinion—need further research. Knowing the mechanisms that govern the stress and strain induced transformation could enable to optimize the thermomechanical treatments and improve the final microstructure properties.

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Warm Formability of Ultra High-Strength Low Alloy TRIP-aided Sheet Steels with Bainitic Ferrite Matrix

Cited by 14 publications

References 13 publications

Stress or strain induced martensitic and bainitic transformations during ausforming processes

Stress or strain induced martensitic and bainitic transformations during ausforming processes

Effects of Silicon and Manganese Contents on V-Bending in High-Strength TRIP-Aided Dual-Phase Steel Sheets with Polygonal Ferrite Matrix

Future Trends on Displacive Stress and Strain Induced Transformations in Steels

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