An interactive micro-void shear localization mechanism in high strength steels

McVeigh, Cahal; Vernerey, Franck J.; Liu, Wing Kam; Moran, Brian; Olson, Gregory B.

doi:10.1016/j.jmps.2006.08.002

Cited by 104 publications

(70 citation statements)

References 34 publications

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“…As is well known, void formation during deformation is controlled by microstructural factors like carbides, inclusions and phase boundaries [11][12]. Especially DP steels show only moderate HE properties due to decohesion of the soft ferrite and hard martensite phases during the local deformation generated by the HE test.…”

Section: Factors Affecting Hole Expansion Ratiomentioning

confidence: 99%

“…These voids occur as a result of decohesion between the ferritic matrix and the hard nitrides ( Figure 8d). Decohesion takes place because the hard TiN does not deform, which leads to shear localization and void formation in the boundary area [11]. It is also evident that voiding intensifies when TiN inclusions crack into smaller fragments (Figures 8e-f).…”

Section: Factors Affecting Hole Expansion Ratiomentioning

confidence: 99%

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The effect of microstructure on the sheared edge quality and hole expansion ratio of hot-rolled 700 MPa steel

Kaijalainen

Kesti

Vierelä

et al. 2017

J. Phys.: Conf. Ser.

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Abstract. The effects of microstructure on the cutting and hole expansion properties of three thermomechanically rolled steels have been investigated. The yield strength of the studied 3 mm thick strip steels was approximately 700 MPa. Detailed microstructural studies using laser scanning confocal microscopy (LCSM), FESEM and FESEM-EBSD revealed that the three investigated materials consist of 1) single-phase polygonal ferrite, 2) polygonal ferrite with precipitates and 3) granular bainite. The quality of mechanically sheared edges were evaluated using visual inspection and LSCM, while hole expansion properties were characterised according to the methods described in ISO 16630. Roughness values (R a and R z ) of the sheet edge with different cutting clearances varied between 12 μm to 21 μm and 133 μm to 225 μm, respectively. Mean hole expansion ratios varied from 28.4% to 40.5%. It was shown that granular bainite produced the finest cutting edge, but the hole expansion ratio remained at the same level as in the steel comprising single-phase ferrite. This indicates that a single-phase ferritic matrix enhances hole expansion properties even with low quality edges. A brief discussion of the microstructural features controlling the cutting quality and hole expansion properties is given.

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Section: Factors Affecting Hole Expansion Ratiomentioning

confidence: 99%

Section: Factors Affecting Hole Expansion Ratiomentioning

confidence: 99%

The effect of microstructure on the sheared edge quality and hole expansion ratio of hot-rolled 700 MPa steel

Kaijalainen

Kesti

Vierelä

et al. 2017

J. Phys.: Conf. Ser.

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“…Traditional hierarchical homogenization conducts averaging over a representative neighborhood of material response at one scale to determine the constitutive behavior at a higher scale (Carrere et al, 2004;Hao et al, 2004;McVeigh et al, 2007). This is typically achieved by conducting direct numerical simulation of a material RVE or by embedding analytical idealizations into formal volume averages.…”

Section: Hierarchical Continuum-to-continuum Scale Linking Approachesmentioning

confidence: 99%

“…Void growth and eventual coalescence are typically modeled as a function of stress triaxiality. McVeigh et al (2007) used direct mesoscale simulations to identify competing mechanisms (i.e., void sheeting) and propose a phenomenological extension to Gurson's flow potential that enhances the coalescence behavior particularly under pure shear loading (does not result in additional porosity increase). Their hierarchical multiscale approach to simulate the effects of two distinct scales of inclusions consisted of: (1) assessing the kinetics of the underlying mechanisms from direct numerical simulation, (2) fitting the modified Gurson flow surface to the simulated response of a unit cell of small inclusions, and (3) using this fit to represent the matrix in another unit cell simulation conducted at a higher scale to address debonding of larger inclusions.…”

Section: Hierarchical Continuum-to-continuum Scale Linking Approachesmentioning

confidence: 99%

A hierarchical framework for the multiscale modeling of microstructure evolution in heterogeneous materials.

Luscher¹

2010

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ACKNOWLEDGEMENTSAs far as I am concerned, there is no better way to celebrate a success than to share the credit with those that have contributed to the effort. Here I share credit with those people that have had tremendous impact to the successful completion of requirements for my PhD degree at Georgia Tech, including this dissertation.Of primary importance in this acknowledgement is to convey how substantial I consider my wife's sacrifices over the last five years. With the sole exception of unmarried PhD candidates, Ido not imagine that there exists a PhD thesis whose acknowledgement section does not make reference to the author's spouse. So I strive to make this acknowledgement of my wife's contributions to my success so compelling and unique that it escapes the status of 'formality'. To attempt this, I will provide a single anecdote selected from five years of worthy material.Stephanie Luscher endured months alone keeping our house in Los Alamos while I was in Atlanta attending classes and fulfilling residency requirements. During that time, she continued working as an engineering design review coordinator at Los Alamos National Lab. While in Oregon to visit family during the winter of 2004-5, a water pipe inside our Los Alamos house froze and burst. Over the next week, 90,000 gallons of water flowed throughout our house ruining just about everything. We returned home and opened soggy Christmas presents from the relative comfort of our car parked in the driveway while contemplating our next course of action.Our house required extensive repairs including a new heating system, kitchen cabinets, flooring, and complete refinishing of the interior walls. We lived in a motor home, a rented house, and a hotel over the course of six months of these repairs. Within two weeks of this happening, I was back in Atlanta and Stephanie was left to manage the reconstruction effort by herself. Of course, this is a single example of how Stephanie has sacrificed, and tended to the many details of life, in order to allow me to focus attention on the work presented within this thesis. Stephanie, I thank iv you for the support and sacrifice you have made to help me accomplish this goal. I'm glad you embraced "my goal" as "our goal."Well in advance of thoughts regarding graduate school, my parents instilled a few helpful traits in me. As a young boy, during hot summers spent roofing with my Dad, Mark Luscher, I learned to work hard and to play hard. My Dad taught me that sometimes "getting the job done" is not elegant; it simply requires you to roll up your sleeves and get to work. As a complement to this, my Mom taught me the importance of precision and attention to detail. Together, my parents have taught me the importance of family, which supersedes all else. Engineering division leader (W-DO), gave me opportunities to excel within the weapons program. Ryan Maupin, group leader for Advanced Engineering Analysis (W-13) has enthusiastically supported and trusted me, both as my manager and friend, to pursue a course of research th...

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“…They found that, for any remote strain-rate field, the enlargement of spherical voids is amplified by a factor of an exponential function of the stress triaxiality. McVeigha et al (2007) studied the micro-void shear localization softening mechanism and modeled the process at the scale of the secondary particles under pure shear loading conditions using the commercially available finite-element software ABAQUS. A comprehensive review of the past research on ductile fracture of solids is presented by Curran et al (1987) and Garrison and Moody (1987).…”

Section: Introductionmentioning

confidence: 99%

Micromechanisms of ductile fracturing of DH-36 steel plates under impulsive loads and influence of polyurea reinforcing

Amini¹,

Nemat‐Nasser²

2010

IUTAM Symposium on Dynamic Fracture and Fragmentation

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Micromechanisms of ductile fracturing of DH-36 steel plates subjected to blast-induced pressure loads are studied experimentally using specially designed dynamic testing facilities. The sample geometry is such that it undergoes controllable fracturing, generally initiated near its center and grows first circumferentially and then radially. Selected fractured samples are sectioned normal to the fracture surfaces, at various intervals along the length of the fracture which extends into the necked and finally to the uniformlydeformed material. The thickness profile of the sample at each cross section is analyzed using optical and scanning electron microscopy. In this manner, we have been able to examine the microstructural evolution that has taken place, from necking inception to fracture initiation and growth, leading to a better understanding of the underpinning mechanisms of the fracturing of this material. The observed ductile fracture involves void nucleation, and void growth and coalescence, creating dimpled fracture surfaces. The examination of the microstructure of the deformed steel samples also revealed that the microstructure does not change M. R. Amini Omnicell Inc., 1201 Charleston Road, Mountain View, CA 94093, USA e-mail: mr_amini_2000@yahoo.com S. Nemat-Nasser (B) Center of Excellence for Advanced Materials, Department of Mechanical and Aerospace Engineering, University of California, La Jolla, San Diego, CA 92093-0416, USA e-mail: sia@ucsd.edu significantly during the deformation and that there are no shearbands developing in and around the fracture zones. Based on the observed micro-scale deformation, a finite-element model was developed to further study the fracturing process, using a physics-based and experimentally-supported temperature-and rate-sensitive constitutive model for DH-36 steel. The finiteelement model was capable of predicting the fracture process of the steel plates rather well. Additional finiteelement simulations are performed to investigate the effect of the polyurea coating on the fracturing and fracture resistance of the plates. These also correlated well with the experimental results.

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An interactive micro-void shear localization mechanism in high strength steels

Cited by 104 publications

References 34 publications

The effect of microstructure on the sheared edge quality and hole expansion ratio of hot-rolled 700 MPa steel

The effect of microstructure on the sheared edge quality and hole expansion ratio of hot-rolled 700 MPa steel

A hierarchical framework for the multiscale modeling of microstructure evolution in heterogeneous materials.

Micromechanisms of ductile fracturing of DH-36 steel plates under impulsive loads and influence of polyurea reinforcing

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