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Title: Predicting Ductility and Failure Modes of TRIP Steels under Different Loading Conditions

Abstract

We study the ultimate ductility and failure modes of a TRIP (TRansformation-Induced Plasticity) 800 steel under different loading conditions with an advanced micromechanics-based finite element analysis. The representative volume element (RVE) for the TRIP800 under examination is developed based on an actual microstructure obtained from scanning electron microscopy (SEM). The evolution of retained austenite during deformation process and the mechanical properties of the constituent phases of the TRIP800 steel are obtained from the synchrotron-based in-situ high-energy X-ray diffraction (HEXRD) experiments and a self-consistent (SC) model. The ductile failure of the TRIP800 under different loading conditions is predicted in the form of plastic strain localization without any prescribed failure criteria for the individual phases. Comparisons of the computational results with experimental measurements suggest that the microstructure-based finite element analysis can well capture the overall macroscopic behavior of the TRIP800 steel under different loading conditions. The methodology described in this study may be extended for studying the ultimate ductile failure mechanisms of TRIP steels as well as the effects of the various processing parameters on the macroscopic behaviors of TRIP steels.

Authors:
; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1000797
Report Number(s):
PNNL-SA-70428
VT0505000; TRN: US201101%%553
DOE Contract Number:
AC05-76RL01830
Resource Type:
Conference
Resource Relation:
Conference: Proceedings of the 10th International Conference on Numerical Methods in Industrial Forming Processes (NUMIFORM 2010): AIP Conference Proceedings, 1252(2):1265-1270
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; AUSTENITE; DEFORMATION; DUCTILITY; MECHANICAL PROPERTIES; MICROSTRUCTURE; PLASTICITY; PLASTICS; PROCESSING; SCANNING ELECTRON MICROSCOPY; STEELS; STRAINS; X-RAY DIFFRACTION; TRIP steel; ductility; failure criteria; retained austenite; phase transformation

Citation Formats

Choi, Kyoo Sil, Liu, Wenning N., Sun, Xin, and Khaleel, Mohammad A.. Predicting Ductility and Failure Modes of TRIP Steels under Different Loading Conditions. United States: N. p., 2010. Web.
Choi, Kyoo Sil, Liu, Wenning N., Sun, Xin, & Khaleel, Mohammad A.. Predicting Ductility and Failure Modes of TRIP Steels under Different Loading Conditions. United States.
Choi, Kyoo Sil, Liu, Wenning N., Sun, Xin, and Khaleel, Mohammad A.. 2010. "Predicting Ductility and Failure Modes of TRIP Steels under Different Loading Conditions". United States. doi:.
@article{osti_1000797,
title = {Predicting Ductility and Failure Modes of TRIP Steels under Different Loading Conditions},
author = {Choi, Kyoo Sil and Liu, Wenning N. and Sun, Xin and Khaleel, Mohammad A.},
abstractNote = {We study the ultimate ductility and failure modes of a TRIP (TRansformation-Induced Plasticity) 800 steel under different loading conditions with an advanced micromechanics-based finite element analysis. The representative volume element (RVE) for the TRIP800 under examination is developed based on an actual microstructure obtained from scanning electron microscopy (SEM). The evolution of retained austenite during deformation process and the mechanical properties of the constituent phases of the TRIP800 steel are obtained from the synchrotron-based in-situ high-energy X-ray diffraction (HEXRD) experiments and a self-consistent (SC) model. The ductile failure of the TRIP800 under different loading conditions is predicted in the form of plastic strain localization without any prescribed failure criteria for the individual phases. Comparisons of the computational results with experimental measurements suggest that the microstructure-based finite element analysis can well capture the overall macroscopic behavior of the TRIP800 steel under different loading conditions. The methodology described in this study may be extended for studying the ultimate ductile failure mechanisms of TRIP steels as well as the effects of the various processing parameters on the macroscopic behaviors of TRIP steels.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2010,
month = 6
}

Conference:
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  • In this study, an advanced micromechanics-based finite element model is developed based on the actual microstructure of a TRIP (TRansformation-Induced Plasticity) 800 steel to model complex deformation behavior of TRIP steels, including its ductile failure behaviors. The evolution of volume fraction of retained austenite during loading and the mechanical properties of the constituent phases of the TRIP 800 steel are obtained from the synchrotron-based in-situ high-energy X-ray diffraction (HEXRD) experiments and a self-consistent (SC) model. The ductile failure of the TRIP 800 under different loading conditions is predicted in the form of plastic strain localization without any prescribed failure criteriamore » for the individual phases. The computational results suggest that the response of the microstructure-based representative volume element (RVE) well represents the overall macroscopic behavior of the deformed TRIP 800 steel under different loading and boundary conditions. The methodology described in this study may be extended for studying the ultimate ductile failure mechanisms of TRIP steels as well as the effects of the various processing parameters on the macroscopic behaviors of TRIP steels.« less
  • Ductile failure of metals is often treated as the result of void nucleation, growth and coalescence. Various criteria have been proposed to capture this failure mechanism for various materials. In this study, ductile failure of dual phase steels is predicted in the form of plastic strain localization resulting from the incompatible deformation between the harder marternsite phase and the softer ferrite matrix. Microstructure-level inhomogeneity serves as the initial imperfection triggering the instability in the form of plastic strain localization during the deformation process. Failure modes and ultimate ductility of two dual phase steels are analyzed using finite element analyses basedmore » on the actual steel microstructures. The plastic work hardening properties for the constituent phases are determined by the in-situ synchrotron-based high-energy X-ray diffraction technique. Under different loading conditions, different failure modes and ultimate ductility are predicted in the form of plastic strain localization. It is found that the local failure mode and ultimate ductility of dual phase steels are closely related to the stress state in the material. Under plane stress condition with free lateral boundary, one dominant shear band develops and leads to final failure of the material. However, if the lateral boundary is constrained, splitting failure perpendicular to the loading direction is predicted with much reduced ductility. On the other hand, under plane strain loading condition, commonly observed necking phenomenon is predicted which leads to the final failure of the material. These predictions are in reasonably good agreement with experimental observations.« less
  • A method for predicting and modeling material failure in solids subjected to impact loading is outlined. The method uses classical void growth models of Gurson and Tvergaard in a material point method (MPM). Because of material softening, material stability is lost. At this point, the character of the governing partial differential equations changes, and localization occurs. This localization results in mesh dependence for many problems of interest. For many problems, predicting the occurrence of material failure and its extent is necessary. To enable this modeling, it is proposed that a discontinuity be introduced into the displacement field. By including amore » dissipation-based force-displacement relationship, the mesh dependence of energy dissipation can be avoided. Additionally, the material point method provides a means of allowing large deformations without mesh distortion or introduction of error through remapping.« less
  • This paper reports on the attempts to demonstrate potential failure modes under combined thermal and transverse loading of unidirectional composites and to validate the predictions of an analytical model through careful design and testing of model composite specimens. Several fiber/matrix combinations are being considered with appropriate variations of the fiber-matrix interfacial bond strength and processing conditions. The interfacial bond strength is reduced in one set of specimens by applying a release agent to the surface of the fiber prior to its incorporation in the matrix. Curing is done both at room and at elevated temperature to account for thermal residualmore » stresses induced form the mismatch in the coefficients of thermal expansion of the constituents. The experimental technique including specimen preparation, test procedures and detection of the sequence of failure events is described. The correlation between the experimental and analytical results is fairly reasonable.« less
  • A fractographic and metallographic investigation was performed on specimens of a tungsten fiber reinforced copper matrix composite (9 vol percent), which had experienced fatigue failures at elevated temperatures. Major failure modes and possible failure mechanisms, with an emphasis placed on characterizing fatigue damage accumulation, were determined. Metallography of specimens fatigued under isothermal cyclic loading suggested that fatigue damage initiates in the matrix. Cracks nucleated within the copper matrix at grain boundaries, and they propagated through cavity coalescence. The growing cracks subsequently interacted with the reinforcing tungsten fibers, producing a localized ductile fiber failure. Examinations of interrupted tests before final failuremore » confirmed the suggested fatigue damage processes.« less