Effect of intermetallic particles and grain boundaries on short fatigue crack growth behaviour in a cast Al–4Cu–3Ni–0.7Si piston alloy

Mbuya, Thomas Ochuku; Gu, Yalong; Thomson, Rachel C.; Reed, P.A.S.

doi:10.1111/ffe.12586

Cited by 10 publications

(7 citation statements)

References 67 publications

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“…Figure a shows that the unHIPped Al0.7Si alloy microstructure mainly comprises the α ‐Al matrix and a network of intermetallic compounds. The secondary dendrite arm spacing (SDAS) was measured using the line intercept method and found to be ≈37.3 ± 10 μm and the volume fraction ( V f ) of the intermetallics was measured and found to be ≈12.1 ± 2.2% . Figure a also shows an intermetallic cluster in the unHIPped microstructure.…”

Section: Results and Analysismentioning

confidence: 98%

Application of X‐Ray Microtomography to Evaluate Complex Microstructure and Predict the Lower Bound Fatigue Potential of Cast Al–7(0.7)Si–4Cu–3Ni–Mg Alloys

et al. 2017

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The 3D architecture of intermetallics and porosity in two multicomponent cast Al-7(0.7)Si-4Cu-3Ni-Mg alloys is characterized using conventional microscopy and X-ray microtomography. The two alloys are found to contain intermetallic phases such as that have complex networked morphology in 3D. The results also show that HIPping does not significantly affect the volume fraction, size, and shape distribution of the intermetallic phases in both alloys. A novel technique similar to serial sectioning that circumvents quantification difficulties associated with interconnected particles is used to quantify the intermetallics. The largest particle size distribution is then correlated to fatigue performance using extreme value analysis to predict the maximum particle size in a sample of S-N fatigue specimens and subsequently, the lower bound fatigue life. The predictions are found to correlate well with fatigue data. The effect of HIPping on porosity characteristics is also characterized. Large pore clusters with complex morphology are observed in the unHIPped versions of both alloys, but more significant in the low Si (Al-0.7Si-4Cu-3Ni-Mg) alloy. However, these are significantly reduced after HIPping. The differences between 2D and 3D pore morphology and size distribution is discussed in terms of the appropriate pore size parameter for fatigue life prediction.

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Section: Results and Analysismentioning

confidence: 98%

Application of X‐Ray Microtomography to Evaluate Complex Microstructure and Predict the Lower Bound Fatigue Potential of Cast Al–7(0.7)Si–4Cu–3Ni–Mg Alloys

et al. 2017

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“…Research in this field has identified that at low loading most of the component life is used for the crack initiation phase [3], while at high loading the component life is used for the crack propagation phase [4,5]. Crack initiation and growth in the early stages are strongly influenced by the microstructure of the material [6][7][8]. To determine the effect of microstructure on the damage process, a study was carried out on an early stage damage due to fatigue loading.…”

Section: Introductionmentioning

confidence: 99%

On the Influence of the Initial Shear Damage to the Cyclic Deformation and Damage Mechanism

Suhartono¹,

Kirman²,

Prawoto³

2022

Metals

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The accuracy and precision of lifetime predictions for cyclically loaded technical components are still lacking. One of the main reasons for the discrepancy between the calculated life time and experimental results is that it is not yet possible to create a model capable of describing the microstructural damage process that occurs in the tested material and to subsequently incorporate this model into the calculation. All of the presently available research results recognize that the growth of microcracks is significantly influenced by the microstructure of the material. In order to take into account the influence of the microstructure on the damage process, research on the very early fatigue damage is carried out. The results are obtained from tension and torsion fatigue testing. For this purpose, the surfaces of the tested specimens are carefully observed to discover and analyze microcracks, which are classified according to their orientation. Moreover, the mechanisms of crack initiation and propagation are major points of interest. Through a mix of mechanical and metallurgical points of view, calculations and multi-level FEA modeling are carried out to gain a better understanding of the properties of the phases. The simulation is based on continuum mechanics, which considers the positions and mechanical metallurgy, which account for each constituent character’s failure laws. It is concluded that both the experimental and computational approaches conform, showing that such an approach is indeed a necessity and should become a trend in the near future. Statistically, microcracks under tension modes are highest at 45° (approximately 30%), while under torsion they are highest at 0° (approximately 20%) with respect to the sample orientation. The influence of the microstructure is explained via the finite element analysis.

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“…Pores were usually considered more detrimental to fatigue properties than oxide film. Several technologies such as hot isostatic pressing (HIP) can reduce pores of Al‐Si alloys with simple geometries . However, their application on piston alloys with complex structure involving thin‐wall sections was seldom reported.…”

Section: Introductionmentioning

confidence: 99%

“…Several technologies such as hot isostatic pressing (HIP) can reduce pores of Al-Si alloys with simple geometries. [30][31][32][33] However, their application on piston alloys with complex structure involving thin-wall sections was seldom reported. The pistons without casting defects may be hardly achieved.…”

Section: Introductionmentioning

confidence: 99%

The influence of defect and temperature on the fatigue behaviours of Al‐Si‐Cu‐Mg‐Ni alloy

Liu

Pang

Wang

et al. 2019

Fatigue Fract Eng Mat Struct

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High‐cycle fatigue (HCF) properties of two Al‐Si‐Cu‐Mg‐Ni alloys with different defect sizes named as alloys A (smaller ones) and B (bigger ones) were investigated at 350°C and 425°C, respectively. The results indicate that fatigue strengths of both alloys decrease as the temperature increases. Fatigue cracks originated from pores and oxide films at both temperatures. They propagated preferentially through cracked matrix at 350°C and debonded interface and grain boundary at 425°C. Alloy A exhibits higher fatigue life and fatigue strength than alloy B at 350°C due to its smaller pore sizes. However, it has slightly worse fatigue properties than alloy B at 425°C because the fatigue crack initiation is controlled by oxide film at this temperature and is not affected by its size. This indicates that there is a transition of predominant initiation site from pores to oxide films when the temperature increases. The fatigue strength estimated through defect size is consistent with the experimental results at 350°C, while unsuitable at 425°C.

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Effect of intermetallic particles and grain boundaries on short fatigue crack growth behaviour in a cast Al–4Cu–3Ni–0.7Si piston alloy

Cited by 10 publications

References 67 publications

Application of X‐Ray Microtomography to Evaluate Complex Microstructure and Predict the Lower Bound Fatigue Potential of Cast Al–7(0.7)Si–4Cu–3Ni–Mg Alloys

Application of X‐Ray Microtomography to Evaluate Complex Microstructure and Predict the Lower Bound Fatigue Potential of Cast Al–7(0.7)Si–4Cu–3Ni–Mg Alloys

On the Influence of the Initial Shear Damage to the Cyclic Deformation and Damage Mechanism

The influence of defect and temperature on the fatigue behaviours of Al‐Si‐Cu‐Mg‐Ni alloy

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