Effect of Tailoring Martensite Shape and Spatial Distribution on Tensile Deformation Characteristics of Dual Phase Steels

The authors simulated the industrially used continuous annealing conditions to process dual phase (DP) steels by using a custom designed annealing simulator. Sixty-seven percentage of cold rolled steel sheets was subjected to different processing routes, including the conventional continuous annealing line (CAL), intercritical annealing (ICA), and thermal cycling (TC), to investigate the effect of change in volume fraction, shape, and spatial distribution of martensite on tensile deformation characteristics of DP steels. Annealing parameters were derived using commercial software, including thermo-calc, jmat-pro, and dictra. Through selection of appropriate process parameters, the authors found out possibilities of significantly altering the volume fraction, morphology, and grain size distribution of martensite phase. These constituent variations showed a strong influence on tensile properties of DP steels. It was observed that TC route modified the martensite morphology from the typical lath type to in-grain globular/oblong type and significantly reduced the martensite grain size. This route improved the strength–ductility combination from 590 MPa–33% (obtained through CAL route) to 660 MPa–30%. Finally, the underlying mechanisms of crack initiation/void formation, etc., in different DP microstructures were discussed.

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Micromechanical Simulation Approach of Dual Phase Steel Artificial Microstructure Using Random Field Model

Materials Science Forum ◽

10.4028/www.scientific.net/msf.1016.534 ◽

2021 ◽

Vol 1016 ◽

pp. 534-540

Author(s):

Mohamed Imad Eddine Heddar ◽

Nadjoua Matougui ◽

Brahim Mehdi

Keyword(s):

Grain Size ◽

Random Field ◽

Dual Phase Steel ◽

Field Model ◽

Volume Fraction ◽

Gaussian Kernel ◽

Dual Phase ◽

Strain Behavior ◽

Proportional Relationship ◽

Dp Steels

In this study, a random field (RF) model with a Gaussian kernel was applied to generate an artificial microstructure of dual phase (DP) steels. Micrographs obtained from Scanning Electron Microscopy (SEM) were analyzed using image processing software to extract the grain size and the volume fraction of each phase. Based on watershed (Ws) segmentation and quantitative analysis, the real and artificial microstructures were compared by analyzing grain features related the solidity, grain size and aspect ratio (the proportional relationship between its width and its height). Consequently, this approach allows to simulate the overall stress-strain behavior of the analyzed microstructures. As a result, it was shown that the strain localization starts to develop at the ferrite/martensite interface and that the RF model could replicate the micromechanical behavior of DP steels.

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Effects of ferrite volume fraction on the tensile deformation characteristics of dual phase twinning induced plasticity steel

Materials & Design (1980-2015) ◽

10.1016/j.matdes.2013.06.033 ◽

2014 ◽

Vol 53 ◽

pp. 99-105 ◽

Cited By ~ 32

Author(s):

A. Imandoust ◽

A. Zarei-Hanzaki ◽

S. Heshmati-Manesh ◽

S. Moemeni ◽

P. Changizian

Keyword(s):

Volume Fraction ◽

Tensile Deformation ◽

Dual Phase ◽

Deformation Characteristics

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MITTAL DI-FORM T700, HF80Y100T

Alloy Digest ◽

10.31399/asm.ad.sa0561 ◽

2007 ◽

Vol 56 (2) ◽

Keyword(s):

Automotive Industry ◽

High Strength ◽

Martensite Phase ◽

Carbon Steels ◽

Ferrite Phase ◽

Dual Phase ◽

Low Carbon ◽

Advanced High Strength Steel ◽

Dp Steels ◽

Soft Ferrite

Abstract MITTAL DI-FORM T700 and HF80Y100T are low-carbon steels with a manganese and silicon composition. Dual-phase (DP) steels are one of the important advanced high-strength steel (AHSS) products developed for the automotive industry. Their microstructure typically consists of a soft ferrite phase with dispersed islands of a hard martensite phase. The martensite phase is substantially stronger than the ferrite phase. The DI-FORM grades exhibit low yield-to-tensile strengths, and the numeric designation in the name corresponds to the tensile strength. This datasheet provides information on microstructure and tensile properties as well as deformation and fatigue. It also includes information on forming. Filing Code: SA-561. Producer or source: Mittal Steel USA Flat Products.

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A Dislocation-Based Theory for the Deformation Hardening Behavior of DP Steels: Impact of Martensite Content and Ferrite Grain Size

Journal of Metallurgy ◽

10.1155/2010/647198 ◽

2010 ◽

Vol 2010 ◽

pp. 1-16 ◽

Cited By ~ 36

Author(s):

Yngve Bergström ◽

Ylva Granbom ◽

Dirk Sterkenburg

Keyword(s):

Plastic Deformation ◽

Grain Size ◽

Deformation Process ◽

Volume Fraction ◽

High Energy ◽

Martensite Content ◽

Plastic Deformation Process ◽

Deformation Hardening ◽

Dp Steels ◽

Ferrite Grain Size

A dislocation model, accurately describing the uniaxial plastic stress-strain behavior of dual phase (DP) steels, is proposed and the impact of martensite content and ferrite grain size in four commercially produced DP steels is analyzed. It is assumed that the plastic deformation process is localized to the ferrite. This is taken into account by introducing a nonhomogeneity parameter, f(ε), that specifies the volume fraction of ferrite taking active part in the plastic deformation process. It is found that the larger the martensite content the smaller the initial volume fraction of active ferrite which yields a higher initial deformation hardening rate. This explains the high energy absorbing capacity of DP steels with high volume fractions of martensite. Further, the effect of ferrite grain size strengthening in DP steels is important. The flow stress grain size sensitivity for DP steels is observed to be 7 times larger than that for single phase ferrite.

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Predicting Plastic Flow Behaviour, Failure Mechanisms and Severe Deformation Localisation of Dual-Phase Steel using RVE Simulation

International Journal of Automotive and Mechanical Engineering ◽

10.15282/ijame.18.1.2021.19.0654 ◽

2021 ◽

Vol 18 (1) ◽

pp. 8601-8611

Author(s):

A. K. Rana ◽

P. P. Dey

Keyword(s):

Plastic Strain ◽

Failure Modes ◽

Volume Fraction ◽

Ferrite Matrix ◽

Martensite Phase ◽

Von Mises Stress ◽

Dual Phase ◽

Strain Partitioning ◽

Deformation Inhomogeneity ◽

Von Mises

In this work, the von Mises stress and plastic strain distribution of Ferrite-Martensite–Dual-Phase (FMDP) steels are predicted at various stages of deformation. The failure modes and volume fraction effect are identified based on Representative Volume Element (RVE). FMDP steel consists of a typical ferrite-matrix phase, in which martensite-islands are dispersed. Recently FMDP steels are increasingly used to the various car parts in demand. 2D-RVEs are also utilised to predict the orientations effect of the martensite phase in the FMDP steels. Based on the position of the element, the boundary conditions (BC) are given in the RVE of FMDP steel microstructures. The failure modes are examined in the form of severe plastic strain localisation. While the distribution of islands in the microstructure varies, as a result, the deformation inhomogeneity increases with a rise of martensite fraction. The results of numerical computation and the trend of experimental failure shown in the literature are compared. This is signifying that the overall macro-behaviour of FMDP steel, as a consequence of stress-strain partitioning and influence of martensite-island volume fractions (MVFs), can be predicted by the finite element (FE) based 2D-RVE modelling.

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