Micromechanisms of fatigue crack growth in cast aluminium piston alloys

Mbuya, Thomas Ochuku; Sinclair, Ian; Moffat, Andrew; Reed, P.A.S.

doi:10.1016/j.ijfatigue.2011.10.015

Cited by 39 publications

(39 citation statements)

References 4 publications

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“…Previous studies [1,3,7,8] on model piston alloys with high Cu and Ni levels (3.9 wt.% Cu and 2.8 wt.%Ni) confirmed that fatigue crack initiation occurs at Si particles and intermetallic particles such as Al 9 FeNi and Al 3 (CuNi) 2 . Some of the model alloys investigated contained reduced Si levels of 6.9 wt.% and 0.67 wt.% as shown in Table 1.…”

Section: Introductionmentioning

confidence: 72%

Section: Crack Growth Micromechanismsmentioning

confidence: 93%

“…In particular, slip lines were observed emanating from the tips of cracks at particles and oriented at ∼45 o to the loading direction [8]. Moreover, the early growth of short cracks into the Al matrix was seen to be controlled by these slip lines [8]. Previous work on other commercial Al alloys has also shown that fatigue cracks that initiate from inclusions or 2 nd phases often seem to be associated with localised slip bands that impinge on the particles [16].…”

Section: Crack Growth Micromechanismsmentioning

confidence: 94%

“…Although the 6.9 wt.%Si alloy did not show pore induced short crack growth behaviour, Moffat [1] observed significant interactions between the crack and eutectic Si structures. It has been shown in a separate publication [8] that the Si particle size and shape distribution are significantly transformed after hipping the strontium modified version of this alloy. It is therefore expected that this Si particle transformation may translate to profound differences in the short crack growth micromechanisms.…”

Section: Introductionmentioning

confidence: 96%

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Micromechanisms of short fatigue crack growth in an Al–Si piston alloy

Mbuya

Reed

2014

Materials Science and Engineering: A

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The short fatigue crack growth behaviour of a model cast aluminium piston alloy has been investigated. This has been achieved using a combination of fatigue crack replication methods at various intervals during fatigue testing and post-mortem analysis of the crack profiles. Crack-microstructure interactions have been clearly delineated using a combination of optical microscopy and scanning electron microscopy. Results show that intermetallic particles and eutectic Al-Si regions play a significant role in determining the crack path and growth rate of short fatigue cracks. It is observed that the growth of short cracks is often retarded or even arrested at intermetallic particles and Al-Si eutectic regions. Crack deflection at intermetallics and eutectic Si is also frequently observed. These results have been compared with the long crack growth behaviour of the alloy.

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Section: Introductionmentioning

confidence: 72%

Section: Crack Growth Micromechanismsmentioning

confidence: 93%

Section: Crack Growth Micromechanismsmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 96%

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Micromechanisms of short fatigue crack growth in an Al–Si piston alloy

Mbuya

Reed

2014

Materials Science and Engineering: A

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“…Initially, the X-ray tomography technique was developed for medical applications [20] and it was not until early 2000 that CT started to be used for characterisation in materials science [21]. Recently CT and μ-CT have been increasingly used within materials science to visualize the microstructure in 3D [22], the interaction of microstructure and fatigue cracks [23][24][25][26][27] etc. It can provide important qualitative (or even quantitative) evaluation of a 3D microstructure and its interaction with crack morphologies by static or in-situ CT-imaging [25,28].…”

Section: Introductionmentioning

confidence: 99%

3-D analysis of fatigue crack behaviour in a shot peened steam turbine blade material

Katsamenis

Mellor

et al. 2015

Materials Science and Engineering: A

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Serial mechanical sectioning and high resolution X-ray tomography have been used to study the three-dimensional morphology of small fatigue cracks growing in a 12 Cr tempered martensitic steam turbine blade material. A range of surface conditions has been studied, namely polished and shot peened (with varying levels of intensity). In the polished (unpeened) condition, inclusions (alumina and manganese sulphide) played an important role in initiating and controlling early fatigue crack behaviour. When fatigue cracks initiated from an alumina stringer, the crack morphology was normally dominated by single stringers, which were always in the centre of the fatigue crack, indicating its primary role in initiation. Manganese sulphide inclusion groups however seemed to dominate and affect the crack path along both the surface and depth crack growth directions. The more intensely shot peened condition did not however evidence inclusion or stringer affected fatigue crack initiation or growth behaviour; sub-surface crack coalescence being clearly observed by both serial sectioning and CT (computed tomography) imaging techniques at a depth of about 150 ~ 180 μm. These sub-surface crack coalescences can be linked to both the extent of the compressive residual stress as well as the depth of the plastic deformation arising from the intense shot peening process. Shot peening appears to provide a different defect population that initiates fatigue cracks and competes with the underlying metallurgical defect populations. The most beneficial shot peening process would in this case appear to "deactivate" 2 the original metallurgical defect population and substitute a known defect distribution from the shot peening process from which fatigue cracks grow rather slowly in the strain hardened surface layer which also contains compressive residual stresses. A benefit to fatigue life in bending, even under Low Cycle Fatigue (LCF) conditions, has been observed in these tests if a sufficiently severe shot peening condition is applied in a constrained notch configuration.

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Transient Microstructural Thermomechanical Fatigue and Deformation Characteristics under Superimposed Mechanical and Thermal Loading in AlSi Based Automotive Diesel Pistons

Morgenstern¹,

Kenningley²

2013

Light Metals 2013

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Micromechanisms of fatigue crack growth in cast aluminium piston alloys

Cited by 39 publications

References 4 publications

Micromechanisms of short fatigue crack growth in an Al–Si piston alloy

Micromechanisms of short fatigue crack growth in an Al–Si piston alloy

3-D analysis of fatigue crack behaviour in a shot peened steam turbine blade material

Transient Microstructural Thermomechanical Fatigue and Deformation Characteristics under Superimposed Mechanical and Thermal Loading in AlSi Based Automotive Diesel Pistons

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