Microstructural aspects of fracture by dimpled rupture

Stone, R. H. Van; Cox, T. B.; Low, J. R.; Psioda, J. A.

doi:10.1179/imr.1985.30.1.157

Cited by 79 publications

(51 citation statements)

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“…Excellent reviews are given by Stone et al (1985), Garrison and Moody (1987) and Wilsdorf (1983). In the remainder of this section the major and most widely known models will be introduced, with due respect to aIl the works by others.…”

Section: Void Nucleationmentioning

confidence: 99%

“…A necessary condition for the nucleation of a microvoid, by decohesion of the partic1e-matrix interface, is that the elastic strain energy released by the particle must be greater than or equal to the energy created by the new surfacees) (Goods and Brown (1979), Thomason (1990), Anderson (1995), Argon and Safoglu (1975), Gurland and Plateau (1963), Garrison and Moody (1987), Wilsdorf (1983), Stone et al (1985) and Tanaka et al (1970)). The local stress caused by dislocation pile-up due to a far field stress which adds to the stress requirement for particle matrix decohesion has been shown by Brown and Stobbs (1976) to be expressed by:…”

Section: Y\mentioning

confidence: 99%

“…Void growth and coalescence is strongly dependent on the extent of stable void growth before void coalescence. An estimated 87% of energy consumed during "dimpled fracture" of high strength steel is absorbed during void growth (Stone et al (1985)). …”

Section: 32: Void Growth and Coalescencementioning

confidence: 99%

“…The ductile failure is more pertinent to this work and thus will be discussed in more detail. The ductile failure mechanism is characterized by three distinct mechanisms (Knot (1989), Knot (1980), Rogers (1967), Garrison and Moody (1987), Wilsdorf (1983), Gurland and Plateau (1963) and Stone et al (1985)):…”

Section: Failure Mechanisms In Metalsmentioning

confidence: 99%

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Micromechanical modeling of dual phase steels

Al-Abbasi

Nemes

2003

International Journal of Mechanical Sciences

140

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Section: Void Nucleationmentioning

confidence: 99%

Section: Y\mentioning

confidence: 99%

Section: 32: Void Growth and Coalescencementioning

confidence: 99%

Section: Failure Mechanisms In Metalsmentioning

confidence: 99%

See 2 more Smart Citations

Micromechanical modeling of dual phase steels

Al-Abbasi

Nemes

2003

International Journal of Mechanical Sciences

140

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“…However, in pure ductile metals where these particles and inclusions are not present, such as in the 99.9% Ta used in this study, the process is inherently different. Initial tensile deformation experiments and post-mortem fractography as noted in Figure 1 show that Ta exhibits significant ductility, but with a valley and ridge surface [6] instead of the classic hemispherical dimpling commonly observed in ductile metal alloys [7]. Through SEM analysis of the fracture surfaces, it was determined that the mating fracture surfaces were mirrored: valleys mated to valleys, and ridges mated to ridges.…”

mentioning

confidence: 99%

Characterization of Void-Dominated Ductile Failure in Pure Ta

et al. 2015

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Prediction of materials reliability requires a physical understanding of the failure process. In the case of void-dominated ductile failure, this includes an understanding of the processes and dominant microstructural variables that lead to void nucleation, growth, and coalescence.Mechanistic descriptions of void-dominated ductile failure are largely based on studies from several decades ago that relied on optical microscopy techniques [1] [2]. This talk will discuss how modern techniques, such as scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), site-specific focused ion beam (FIB) sample preparation, and transmission electron microscopy (TEM), can enable new insight into the ductile failure process, particularly at the nano to microscale. Because this work is part of a collaborative effort to develop predictive computational models for failure of BCC metals, experiments are focused on characterizing the void-dominated ductile failure process in pure Ta.In metal alloys the initiation of voids is primarily driven by decohesion at second-phase particles or inclusions [3][4] [5]. However, in pure ductile metals where these particles and inclusions are not present, such as in the 99.9% Ta used in this study, the process is inherently different. Initial tensile deformation experiments and post-mortem fractography as noted in Figure 1 show that Ta exhibits significant ductility, but with a valley and ridge surface [6] instead of the classic hemispherical dimpling commonly observed in ductile metal alloys [7]. Through SEM analysis of the fracture surfaces, it was determined that the mating fracture surfaces were mirrored: valleys mated to valleys, and ridges mated to ridges. Thus the deformation was void dominated, but the mechanism of void initiation was unclear.To further study the void initiation process in Ta and the progression of damage towards failure, interrupted tensile specimens as a function of percent remaining strength were prepared. By polishing the samples to their mid-plane as seen in Figure 2a, where triaxial stresses are highest and thus voids likely to be present, we studied the progression of void structures as a function of strain. Using EBSD analysis to characterize local misorientations in voided regions, we determined that voids in Ta are formed within grains, as opposed to at grain boundaries, along bands of high misorientation with respect to the tensile axis. Figure 2b shows elongated, inclined [001] subgrains alternating with regions of [122] associated with voids in a Ta tensile bar elongated to 60% remaining strength. We hypothesize that the dislocation processes giving rise to localized regions of high misorientation within grains are promoting the collection of vacancies, thus inducing void nucleation. This hypothesis is being further explored through site-specific FIB sample preparation and TEM analysis of dislocation structures in deformed Ta samples.

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