Effect of Thermal Aging on Ductile-Brittle Transition Temperature of Modified 9Cr-1Mo Steel Evaluated with Reference Temperature Approach Under Dynamic Loading Condition

Sathyanarayanan, S.; Basu, Joysurya; Moitra, A.; Sasikala, G.; Singh, Vakil

doi:10.1007/s11661-012-1510-0

Cited by 30 publications

(14 citation statements)

References 15 publications

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“…However, uncontrolled precipitation may lead to deterioration of mechanical properties in high strength structural materials. Although the physics of dispersion strengthening is relatively better understood, degradation of mechanical properties due to uncontrolled precipitation of Laves phases in structural materials and steels is almost not understood [14]. It has been postulated that the precipitation of Laves phases in steel matrix reduces solid solution strengthening effects and additionally contributing factors like inherent limited plasticity of the phase and the weak precipitate-matrix interface lead to such degradation [15].…”

Section: Introductionmentioning

confidence: 99%

Structure imaging and vanadium substitution in cubic TiCr₂Laves phase

Ghosh

Sharma

Basu

et al. 2015

Philosophical Magazine

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Properties of Laves phase compounds can be tailored by alloying and microstructural engineering. V-substituted cubic TiCr 2 Laves phase has been studied to understand the location of V atoms in the lattice, by structural imaging and first-principle computations. Even though Ti, V and Cr appear next to each other in the periodic table, V preferentially replaces the Ti lattice producing anti-site defects. The defect formation energy for V substitution in Ti and in Cr lattice is 0.29 and 0.40 eV, respectively. V replacement in the Ti lattice generates atomic scale strain. Atomic numbers of V, Ti and Cr being very close, this phase is not quite suitable for incoherent imaging for understanding the structure and the chemistry. Instead, difference in channelling behaviour of electron waves along the Ti columns and along the Cr columns could be exploited to preferentially image the individual atom columns. Nature of the exit phase wave, phase and amplitude has been used to understand the contrast qualitatively. The intensity distribution of any particular atom column that is disturbed by the presence of foreign atom has been used to detect the position of V atoms. This method could be extended to study other Laves phases and complex intermetallic structures to understand their structure, defects and interfaces. IntroductionLaves phases, a group of topologically close-pack hard intermetallic compounds with AB 2 stoichiometry, are known to form at a particular radius ratio of A and B (r A /r B = 1.22) atoms [1]. However, a considerable deviation from ideal radius ratio (r A /r B = 1.05-1.67) [2] is observed in practice and the phase can often accommodate non-stoichiometry [3]. There are three allotropic polymorphs of Laves phase i.e. cubic (cF24), hexagonal (hP12) and double-hexagonal (hP24) [2]. Since the discovery of this phase, more than a thousand binary and ternary Laves phase forming compounds with a range of interesting properties and varying crystal chemistry have been reported in the literature [4]. These attributes could be exploited to design single-phase or multiphase

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Section: Introductionmentioning

confidence: 99%

Structure imaging and vanadium substitution in cubic TiCr₂Laves phase

Ghosh

Sharma

Basu

et al. 2015

Philosophical Magazine

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“…For instance, Dimmler et al [21] reported stunted fatigue resistance of the steel due to Laves phase precipitation. In the same line, Sathyanarayanan et al [6] reported a drop in dynamic fracture toughness with the precipitation of Laves phase. Dimmler et al [23] have attributed this to be a result of massive nucleation and growth of cracks/voids at low strain values on regions adjacent to the Laves phase.…”

Section: Failure Mechanismsmentioning

confidence: 76%

“…In an earlier study [6] on modified 9Cr-1Mo steel, formation of Laves phase has been reported after an aging treatment of 10,000 h at 873 K (600 °C) and 923 K (650 °C). Therefore, two distinct samples, each from the respective aging treatment from the same steel, chemical composition of which is given in Table 1, have been used for this study.…”

Section: Samplesmentioning

confidence: 93%

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Understanding Laves phase precipitation induced embrittlement of modified 9Cr–1Mo steel

Sarwat

Basu

2018

SN Appl. Sci.

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Precipitation of Laves phase in steels is often identified as the primary cause for the degradation of mechanical properties. Analytical electron microscopy and thermodynamic modelling have been used in this study to understand the Lave phase precipitation induced damage initiation process in modified 9Cr-1Mo steel, exposed to high temperature for 10,000 h. The results have suggested that in addition to void nucleation at the interface and de-cohesion, the limited plasticity of the Laves phase is also a predominant mechanism for crack initiation in this material. The thermodynamic propensity of Laves phase precipitation around the carbides and the underlying role of local chemistry have also been studied. Binary Laves phases have been found to be stabilized by ternary additions.

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“…This concept has been further analysed by Odette et al [8] in steels for fusion reactor application. Considering that the effect of dynamic loading would give rise to conservative DBTT, the reference temperature was evaluated under dynamic loading condition as T 0 dy by Moitra et al [9][10][11][12] for 9Cr-1Mo family of steels. Further, fracture in the transition temperature regime is a crack initiation controlled event, as most of the energy to fracture would be associated with the crack initiation process rather than its propagation.…”

Section: Introductionmentioning

confidence: 99%

A Study of Fracture Mechanisms in RAFM Steel in the Ductile to Brittle Transition Temperature Regime

Moitra

Dasgupta

Sathyanarayanan

et al. 2014

Procedia Engineering

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The fracture behaviour of a Reduced Activation Ferritic Martensitic Steel (RAFM) has been studied within the Ductile to Brittle Transition Temperature (DBTT) regime. The DBTT has been determined by ASTM E 1921 based reference temperature approach under dynamic loading condition. The dynamic reference temperature (T 0 dy ) was found to be − 33.8 °C. The fracture mechanism has been studied by extracting TEM specimens precisely at the crack initiation sites using focused ion beam (FIB) technique in a high resolution dual beam scanning electron microscope. Detailed analytical TEM studies revealed that the morphology of carbides play a crucial role in the initiation of a crack. The larger ellipsoidal carbides, which were found to be Crrich, have been found to be responsible for dislocation piles ups. The shorter edge of these ellipsoidal carbides are areas of high stress concentration and were found to initiate cracks by decohesion of the particle-matrix interface. On the contrary, the iron rich carbides have been found to be smaller, more spherical, and thus less effective in blocking dislocation movement and therefore formation of pile ups. The results, which reveal an important mechanism towards crack initiation in ferritic-martensitic steels, will be presented in detail.

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Effect of Thermal Aging on Ductile-Brittle Transition Temperature of Modified 9Cr-1Mo Steel Evaluated with Reference Temperature Approach Under Dynamic Loading Condition

Cited by 30 publications

References 15 publications

Structure imaging and vanadium substitution in cubic TiCr₂Laves phase

Structure imaging and vanadium substitution in cubic TiCr₂Laves phase

Understanding Laves phase precipitation induced embrittlement of modified 9Cr–1Mo steel

A Study of Fracture Mechanisms in RAFM Steel in the Ductile to Brittle Transition Temperature Regime

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Effect of Thermal Aging on Ductile-Brittle Transition Temperature of Modified 9Cr-1Mo Steel Evaluated with Reference Temperature Approach Under Dynamic Loading Condition

Cited by 30 publications

References 15 publications

Structure imaging and vanadium substitution in cubic TiCr2Laves phase

Structure imaging and vanadium substitution in cubic TiCr2Laves phase

Understanding Laves phase precipitation induced embrittlement of modified 9Cr–1Mo steel

A Study of Fracture Mechanisms in RAFM Steel in the Ductile to Brittle Transition Temperature Regime

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Structure imaging and vanadium substitution in cubic TiCr₂Laves phase

Structure imaging and vanadium substitution in cubic TiCr₂Laves phase