Plasticity and fracture modeling of quench-hardenable boron steel with tailored properties

Eller, Tom; Greve, Lars; Andres, Michael; Medricky, M.; Hatscher, Ansgar; Meinders, Vincent T.; Boogaard, A.H. van den

doi:10.1016/j.jmatprotec.2013.12.015

Cited by 84 publications

(58 citation statements)

References 15 publications

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“…In this case, it is not possible to determine initial Swift and Voce fits for the exponential mixing law (Equation 3) as it was done in Subsection 4.1. For that reason, and in order to keep the number of free model parameters within bounds, the 3-parameter Swift law will be used, which is known to provide good results for softer material grades [18]: Figure 13 shows an average curve of the experimental force-displacement results together with the sample points used for the optimization and two simulation results: with initial and final (optimized) parameters. When comparing the two simulated curves, it can be seen that the strain hardening parameters of the HAZ have a significant influence on the global force-displacement behavior, which is a good result as this increases the accuracy of the optimization routine.…”

Section: Haz Plasticity Modelmentioning

confidence: 99%

Identification of Plasticity Model Parameters of the Heat-Affected Zone in Resistance Spot Welded Martensitic Boron Steel

Eller

Greve

Andres

et al. 2015

KEM

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A material model is developed that predicts the plastic behavior of fully hardened 22MnB5 base material and the heat-affected zone (HAZ) material found around its corresponding resistance spot welds (RSWs). Main focus will be on an accurate representation of strain fields up to high strains, which is required for subsequent calibration of the fracture behavior of both base material and HAZ. The plastic behavior of the base material is calibrated using standard tensile tests and notched tensile tests and an inverse FEM optimization algorithm. The plastic behavior of the HAZ material is characterized using a specially designed tensile specimen with a HAZ in the gage section. The exact location of the HAZ relative to the center of the RSW is determined using microhardness measurements, which are also used for mapping of the material properties into an FE-model of the specimen. With the parameters of the base material known, and by assuming a linear relation between the hardness and the plasticity model parameters of base material and HAZ, the unknown HAZ parameters are determined using inverse FEM optimization. A coupon specimen with HAZ is used to validate the model at hand.

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Section: Haz Plasticity Modelmentioning

confidence: 99%

Identification of Plasticity Model Parameters of the Heat-Affected Zone in Resistance Spot Welded Martensitic Boron Steel

Eller

Greve

Andres

et al. 2015

KEM

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“…An extended Swift law is introduced for fitting all three main grades using the same analytical function [1]. The modified Mohr-Coulomb fracture model (mMC) by Bai and Wierzbicki [2] is used in this work, which is based on the classical Mohr-Coulomb (MC) criterion [3,4].…”

Section: Hardness-based Necking/post-necking Modelmentioning

confidence: 99%

“…The modified Mohr-Coulomb fracture model (mMC) by Bai and Wierzbicki [2] is used in this work, which is based on the classical Mohr-Coulomb (MC) criterion [3,4]. A review of the fracture model theory and the combined experimental/numerical model parameter identification procedure for the three main grades is provided in [1]. In FIGURE 1c, the mMC fracture curves for the main grades (thick solid lines) and some interpolated curves are shown.…”

Section: Hardness-based Necking/post-necking Modelmentioning

confidence: 99%

“…It will be shown subsequently that due to the length-based formulation the post-necking model is quite mesh-independent. Generalized hardness-based necking model: Basically, our model implies a 2-phase decomposition of the material phases for continuous cooling of the material [1]. Depending on the material hardness, the material contains ferrite/pearlite plus bainite phases, or bainite plus martensite phases, where the "pure" phases (ferrite/pearlite, bainite, and martensite) represent the three main material grades characterized and modeled in the previous sections.…”

Section: Figure 1cmentioning

confidence: 99%

“…The model has been integrated into the modular user material model frame work (MMM) developed at Volkswagen Group Research [1]. The present paper focusses on the development of the shell element extensions.…”

Section: Introductionmentioning

confidence: 99%

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Hardness-based plasticity and fracture model for quench-hardenable boron steel (22MnB5)

Greve

Eller

Medricky

et al. 2013

AIP Conference Proceedings

Self Cite

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Abstract.A comprehensive strain hardening and fracture characterization of different grades of boron steel blanks has been performed, providing the foundation for the implementation into the modular material model (MMM) framework developed by Volkswagen Group Research for an explicit crash code. Due to the introduction of hardness-based interpolation rules for the characterized main grades, the hardening and fracture behavior is solely described by the underlying Vickers hardness. In other words, knowledge of the hardness distribution within a hot-formed component is enough to set up the newly developed computational model. The hardness distribution can be easily introduced via an experimentally measured hardness curve or via hardness mapping from a corresponding hot-forming simulation. For industrial application using rather coarse and computationally inexpensive shell element meshes, the user material model has been extended by a necking/post-necking model with reduced mesh-dependency as an additional failure mode. The present paper mainly addresses the necking/post-necking model.

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The Effect of Intercritical Annealing on the Microstructure and Mechanical Properties of Ferritic–Martensitic Two‐Phase Steels

Wolf¹,

Nürnberger²,

Rodman³

et al. 2016

steel research int.

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Modified press‐hardening processes are very attractive for manufacturing safety‐relevant vehicle body parts from steels with martensitic–ferritic microstructures. In the process developed, the formation of the two‐phase microstructure and the hot sheet forming simultaneously occur subsequently to an intercritical annealing. By contrast, previously used process chains do not integrate setting of a multi‐phase microstructure within the forming step. In order to successfully combine the intercritical annealing with the actual forming, comprehensive knowledge of the microstructural evolution and the resulting mechanical properties is needed. Specifically, different heat‐treating routes are used to obtain different microstructures of ferritic–martensitic dual‐phase steels and partial martensitic steels. As a result of intercritical annealing in the temperature range of Ac1–Ac3, it is possible to vary the martensite volume fractions from 7 to 96 vol%. The data obtained can be employed for numerically describing the microstructural transformation and for designing the heat treatment process. It is demonstrated that this combined process allows for designing steels that feature properties that are similar to complex‐phase steels.

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Plasticity and fracture modeling of quench-hardenable boron steel with tailored properties

Cited by 84 publications

References 15 publications

Identification of Plasticity Model Parameters of the Heat-Affected Zone in Resistance Spot Welded Martensitic Boron Steel

Identification of Plasticity Model Parameters of the Heat-Affected Zone in Resistance Spot Welded Martensitic Boron Steel

Hardness-based plasticity and fracture model for quench-hardenable boron steel (22MnB5)

The Effect of Intercritical Annealing on the Microstructure and Mechanical Properties of Ferritic–Martensitic Two‐Phase Steels

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