Residual‐Stress Predictions in Polycrystalline Alumina

Vedula, Venkata; Glass, S. Jill; Saylor, David M.; Rohrer, Gregory S.; Carter, W. Craig; Langer, Stephen A.; Fuller, Edwin R.

doi:10.1111/j.1151-2916.2001.tb01119.x

Cited by 118 publications

(65 citation statements)

References 25 publications

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“…Para altos ângulos, o comportamento observado é o oposto. O processo de mudança da microestrutura é considerado como origem dos processos de formação das tensões residuais em cerâmicas policristalinas, [5]. Durante a formação da microestrutura, fronteiras com alta mobilidade e energias são suscetíveis a serem eliminadas, alterando desse modo as orientações da rede cristalina e misorientação dos contornos dos grãos.…”

Section: Introductionunclassified

Mudanças Microestruturais Após Soldagem

Gomes¹,

Peripolli²,

Gurova³

et al. 2017

Anais Do Congresso Anual Da ABM

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ResumoProcessos metalúrgicos durante soldagem provocam tensões residuais em peças soldadas. Recentemente foi observado um efeito de redistribuição das tensões residuais de soldagem num período de até duas semanas após o termino do processo de soldagem. Existe hipótese nossa que esta redistribuição das tensões está associada a mudança na microestrutura que ocorre no material após do processo de soldagem. Para provar esta hipótese, uma simulação física dos ciclos térmicos do processo de soldagem foi realizada utilizando a simulação física termomecânica (GLEEBLE). Através da técnica de microscopia eletrônica de varredura associada a técnica de difração de elétrons retroespalhados (MEV-EBSD) foi observada a variação da misorientação dos grãos e mudanças na microestrutura do material nos primeiros dias após soldagem, acompanhada de redistribuição das tensões residuais. Palavras-chave: Soldagem; Microestrutura; Misorientação; Tensões residuais. MICROSTRUCTURE CHANGES AFTER WELDING AbstractMetallurgical processes during welding produce residual stresses in different zones of the welded parts. Our recent works report the effect of residual stress redistribution in a relatively short, up to two weeks, period after the welding procedure. The hypothesis that the observed stress relaxation phenomenon is associated to the microstructure evolution that occur in the material after the end of the welding procedure was proposed. To prove this hypothesis a physical simulation of the influence of the welding thermal cycles on the base metal with GLEEBLE equipment was performed. Using SEM EBSD technique the variation of grain boundary misorientation and changes in the microstructure accompanied by the residual stresses redistribution in the first dais after welding were.

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Section: Introductionunclassified

Mudanças Microestruturais Após Soldagem

Gomes¹,

Peripolli²,

Gurova³

et al. 2017

Anais Do Congresso Anual Da ABM

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“…(1), which is comparable to those derived by stress simulations. 27,29,30) 3. Correlation between stress and grain misorientation It can be seen that Δν changes sharply at some grain boundaries.…”

Section: Luminescence Properties Of Single-crystal and Polycrystallinmentioning

confidence: 99%

“…[26][27][28] To date, the evaluation of grain-anisotropy-induced stress has been limited to numerical stress simulation using grainorientation-limited polycrystalline ceramics as a model. 26,27,[29][30][31] Simultaneous high-resolution imaging of stress and grain orientation by near-field luminescence spectroscopy will provide important insights for further advancements of local stress simulation.…”

Section: Introductionmentioning

confidence: 99%

Correlation between the local stress and the grain misorientation in the polycrystalline Al₂O₃ measured by near-field luminescence spectroscopy

Tomimatsu

Takigawa

2018

Jpn. J. Appl. Phys.

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Owing to its high spatial resolution, near-field spectroscopy is a useful method for sensing the stress in a narrow region of submicron order. Here, on the basis of the highly resolved images obtained by near-field luminescence spectroscopy, we propose a statistical method of analyzing grain anisotropy-induced stress in polycrystalline Al 2 O 3 . We focus on two characteristics of a spectra: the intensity ratio and peak shift of luminescence of two lines (R 1 and R 2 ) from Al 2 O 3 to discuss crystal orientation and stress, respectively. By incorporating the concept of the crystal misorientation parameter using intensity ratio, an apparent correlation between the magnitude of stress and the misorientation is found. This correlation analysis provides an important insight for the investigation of local thermal stress in Al 2 O 3 .

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“…However, measurement of the residual stresses in such a small grain is almost impossible at the present. 15) Fig. 1.…”

Section: Strength and Fracture Toughnessmentioning

confidence: 99%

Toughening mechanism and frontal process zone size of ceramics

Araki¹,

Nishimura

Choi

et al. 2009

J. Ceram. Soc. Japan

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In order to improve the fracture toughness of intrinsically brittle ceramics, it is essential to expand the frontal process zone (FPZ) ahead of a crack tip. Nanocomposites proposed by Niihara utilize dislocations generated around the dispersed nanosized particles in matrix and expand the FPZ. In this paper, we discussed the toughening mechanism of ceramics using our experimental data on alumina-based nanocomposites, focusing on fundamental theories of fracture mechanics, such as Griffith-Irwin energy equilibrium and the local fracture criterion. We estimated the FPZ size using an indirect technique proposed recently, and clarified that the FPZ expansion toughening mechanism is achieved in nanocomposites by means of dislocation activities. The results revealed that ceramics with a larger FPZ size had higher fracture toughness and properly annealed nanocomposites had the largest FPZ size. The FPZ expansion mechanism in nanocomposites was considered that sessile dislocations generated around a crack tip in matrix, served as nano-crack nuclei, and hence expanded the FPZ size. It is clarified that the critical local stress is the strength of an infinite plate with no crack, and must be the true strength with no size effect. The fracture toughness, the critical local stress, and the FPZ size are the mutually dependent material properties, and the relation among them is clarified.

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Residual‐Stress Predictions in Polycrystalline Alumina

Cited by 118 publications

References 25 publications

Mudanças Microestruturais Após Soldagem

Mudanças Microestruturais Após Soldagem

Correlation between the local stress and the grain misorientation in the polycrystalline Al₂O₃ measured by near-field luminescence spectroscopy

Toughening mechanism and frontal process zone size of ceramics

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Residual‐Stress Predictions in Polycrystalline Alumina

Cited by 118 publications

References 25 publications

Mudanças Microestruturais Após Soldagem

Mudanças Microestruturais Após Soldagem

Correlation between the local stress and the grain misorientation in the polycrystalline Al2O3 measured by near-field luminescence spectroscopy

Toughening mechanism and frontal process zone size of ceramics

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Product

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Correlation between the local stress and the grain misorientation in the polycrystalline Al₂O₃ measured by near-field luminescence spectroscopy