Direct high resolution in situ SEM observations of very small fatigue crack growth in the ultra-fine grain aluminium alloy IN 9052

Zhang, Jia Zhen; Zhang, Jiazhong; Zhao, Meng

doi:10.1016/j.scriptamat.2003.12.016

Cited by 28 publications

(13 citation statements)

References 9 publications

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“…The fracture morphology of the unidirection rolled samples from Figure 12D,H supports the fact by revealing a brittle cleavage failure. The crack interaction with such second phase particles/precipitates has led to crack propagation through particle de‐bonding or matrix–particle interface de‐bonding, as observed by Kumar and Curtin 27 and Zhang et al 28 During cross rolling, that is, when the material was rolled in both the direction, the second phase particles/precipitates are aligned in a different orientation. Hence, the second phase particles are parallel and perpendicularly oriented.…”

Section: Discussionmentioning

confidence: 97%

Effect of crack path and high angle grain boundaries on fracture toughness and fatigue behaviour of cryorolled AA2219

Blessto

Sivaprasad

Muthupandi

et al. 2020

Fatigue Fract Eng Mat Struct

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AA2219 aerospace alloys in T87 condition were rolled at room temperature and subzero temperature, followed by analysis on its tensile, fracture toughness and fatigue crack growth characteristics. The cryorolled alloy exhibits lower plane stress fracture toughness (50 kJ m −2) than T87 condition (99 kJ m −2) because of higher high angle grain boundaries (HAGBs) which causes an inability to withstand the cyclic deformation. Nevertheless, the cryorolled alloy has shown higher tensile properties and crack growth resistance due to finer grains and large plastic zone size in the crack tip. The unidirectional rolled samples undergo a distinctive zigzag path than the cross-directional rolled alloy because of deflection from the orderly oriented second phase particles.

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Section: Discussionmentioning

confidence: 97%

Effect of crack path and high angle grain boundaries on fracture toughness and fatigue behaviour of cryorolled AA2219

Blessto

Sivaprasad

Muthupandi

et al. 2020

Fatigue Fract Eng Mat Struct

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“…Some studies strongly support the crack closure effect on fatigue crack growth 6–9 . Other studies indicate that crack closure does not contribute much to the crack growth 10–14 . Elber 5 pointed out that fatigue cracks remained closed during part of the loading process and proposed an effective stress intensity factor range to account for the crack closure.…”

Section: Introductionmentioning

confidence: 98%

“…[6][7][8][9] Other studies indicate that crack closure does not contribute much to the crack growth. [10][11][12][13][14] Elber 5 pointed out that fatigue cracks remained closed during part of the loading process and proposed an effective stress intensity factor range to account for the crack closure. Many related studies have been done on the crack using experimental investigation, numerical analysis as well as theoretical studies.…”

Section: Introductionmentioning

confidence: 99%

Plastic zone size estimation under cyclic loadings using in situ optical microscopy fatigue testing

Zhang

Liu

2011

Fatigue Fract Eng Mat Struct

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A B S T R A C T An in situ optical microscopy fatigue testing is proposed in this paper to investigate the forward and reversed plastic zone size under cyclic loadings for Al-7075-T6. This experimental study is used to verify the hypotheses in a recently developed small time scale formulation of fatigue crack growth. During the testing, the entire cyclic loading cycle is divided into a certain number of steps. Images of the crack tip are taken at each step. The full strain field around the crack tip is determined using the digital image correlation (DIC) technique. The plastic zone size is obtained by combining the DIC results and the material constitutive relationship. Experimental measurements from the proposed study are compared with theoretical predictions. It is observed that the crack closure has a large effect on the reversed plastic zone size. The plastic zone size remains almost constant when the unloading path is below a certain stress level, which is one of the hypotheses used in a previous crack growth model. Discussions are given for the modelling of plastic zone size variation under cyclic loadings and several conclusions are drawn based on the current investigation. N O M E N C L A T U R Eσ = Applied stress K = Applied stress intensity factor K closure = Crack closure stress intensity factor σ closure = Crack closure stress a = Crack length K open = Crack opening stress intensity factor θ = Crack tip opening angle δ = CTOD K eff = Effective stress intensity factor range F = Geometry correction factor ρ f = Forward plastic zone size ρ r = reversed plastic zone size ε y = Tensile yield strain σ y = Tensile yield strength D = Thickness of the specimen W = Width of the specimen E = Young's modulus I N T R O D U C T I O NVarious approaches have been proposed in the past to correlate the fatigue damage with applied driving forces. EarCorrespondence: Y. Liu.

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“…In situ scanning electron microscopy (SEM) has recently become a direct and effective tool to investigate crack initiation, propagation, and fracture mechanisms [8][9][10][11][12][13][14]. The fracture behavior of A390 aluminum cylinder liner alloys under static loading was investigated by in situ SEM [15].…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Crack Propagation and Strain Fields Evolution around a Crack Tip in 5A05 Aluminum Alloy

Zhao

et al. 2018

Metals

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In situ scanning electron microscopy three-point bending test was employed in this study to investigate the crack initiation and propagation in 5A05 aluminum alloy. The microscale strain fields around the crack tip were measured by using the geometric phase analysis method. Results show that prior to the crack initiation, the normal strain εyy (y direction is perpendicular to the load direction) was tensile around the notch, whereas the normal strain εxx (x direction is parallel to the load direction) was compressive around the notch. The shear strain εxy was nearly zero. With the increase in load, the normal strains εyy and εxx gradually increased, but the change in shear strain εxy was not evident. When the stresses at several sharp points at the notch root reached the breaking strengths, a few microcracks initiated at these points. At this moment, the normal strains εyy and εxx were much greater than the shear εxy, and dominated the strain fields around the crack tip. In the crack propagation process, the normal strains εyy and εxx, and the shear strain εxy dominated the strain fields around the crack tip, thereby leading to a Z-form of crack propagation path in the specimen.

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Direct high resolution in situ SEM observations of very small fatigue crack growth in the ultra-fine grain aluminium alloy IN 9052

Cited by 28 publications

References 9 publications

Effect of crack path and high angle grain boundaries on fracture toughness and fatigue behaviour of cryorolled AA2219

Effect of crack path and high angle grain boundaries on fracture toughness and fatigue behaviour of cryorolled AA2219

Plastic zone size estimation under cyclic loadings using in situ optical microscopy fatigue testing

Experimental Investigation of Crack Propagation and Strain Fields Evolution around a Crack Tip in 5A05 Aluminum Alloy

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