A Comparative Investigation on the High Temperature Fatigue of Three Cast Aluminum Alloys

Engler-Pinto, Carlos; Lasecki, John; Boileau, James; Allison, J.

doi:10.4271/2004-01-1029

Cited by 13 publications

(11 citation statements)

References 15 publications

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“…At 250°C, the creep strain rate is on the order of 10 -8 per second at stress levels of 60 to 80 MPa. [28] As such, strain caused by creep during each cycle is approximately 10 -10 at conventional frequency and 10 -13 at ultrasonic frequency. These values are far below the fatigue-strain amplitude, which is on the order of 10 -3 .…”

Section: A Effect Of Frequency and Environment On Fatigue-crack Propmentioning

confidence: 99%

Effect of Frequency, Environment, and Temperature on Fatigue Behavior of E319 Cast-Aluminum Alloy: Small-Crack Propagation

Zhu

Jones

Allison

2008

Metall Mater Trans A

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The influence of test frequency on fatigue-crack propagation behavior of small cracks in E319 cast-aluminum alloy was studied using ultrasonic and conventional test techniques. It was observed that fatigue cracks grow faster at 30 Hz than at 20 kHz in air at both 20°C and 250°C. The effect of frequency on the fatigue-crack growth rates was attributed to an environmental effect. For E319 cast-aluminum alloy, fatigue-crack growth rate increases with increasing water exposure (characterized by the ratio of water partial pressure over test frequency, P/f), and this behavior can be estimated using a modified superposition model. The effect of temperature on fatigue-crack growth behavior was primarily attributed to the effect of temperature on Young's modulus and yield strength. The environmental contribution to fatigue-crack growth rates modestly decreases with increasing temperature.

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Section: A Effect Of Frequency and Environment On Fatigue-crack Propmentioning

confidence: 99%

Effect of Frequency, Environment, and Temperature on Fatigue Behavior of E319 Cast-Aluminum Alloy: Small-Crack Propagation

Zhu

Jones

Allison

2008

Metall Mater Trans A

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“…[5] Nevertheless, as a simple model, we wish to see whether there exists any correlation between the calculated phase fractions of equilibrium phases and the measured yield strength of respective alloys. So we have collected the measured yield strength data [5,21,41,42] for these alloys, which are plotted in Figure 8. For comparison, we also show a plot of the calculated phase fractions (Thermotech, 0°C) of the dominant phases (Table VI) in the respective alloys.…”

Section: Correlation Between Calculated Phase Fractions and Measumentioning

confidence: 99%

Comparison of thermodynamic databases for 3xx and 6xxx aluminum alloys

Ravi

Wolverton

2005

Metall Mater Trans A

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Computational thermodynamics, or Calculation of Phase Diagram (CALPHAD) methods have proven useful in applications to modeling a variety of alloy properties. However, the methods are only as accurate as the thermodynamic databases they use, and two commercial thermodynamic databases exist for aluminum alloys: Thermotech and Computherm. In order to provide a critical comparison of these databases, we used both the databases to calculate equilibrium solid-state phase fractions and phase diagram isothermal sections of several industrial aluminum alloys: a 319-type and 356 cast alloys, as well as the wrought alloys 6022 and 6111. All of these alloys may be generically described as being based on the Al-Mg-Si-Cu quaternary with other additions such as Fe, Mn, and Zn. Although many of the results are consistent between the two databases, several qualitative and quantitative differences were observed. Many of these differences are found to be due to the intermetallic compounds involving Fe, Mn, Cr, and Zn. On the other hand, thermodynamics involving only phases from the Al-Mg-Si-Cu quaternary show good agreement between the databases, although some small differences still exist, particularly involving the quaternary Q phase. To understand and assess these differences, formation enthalpies and reaction energies from the databases were compared against density functional first-principles energetics. These comparisons indicate possible avenues for future improvements of Al-alloy thermodynamic databases. Finally, we demonstrate an interesting correlation between the calculated phase fractions and the measured yield strengths across this wide family of 3xx cast and 6xxx wrought alloys.

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“…In addition to aluminium cylinder heads being lighter, aluminium alloys in cylinder heads also offer the advantage of high thermal conductivity and increased corrosion resistance compared to their cast iron counterparts [1,2]. As the drive to advance the engine efficiency increases, the operating temperatures have kept increasing with the engine peak temperature reported well above 200 • C in recent times [3][4][5]. Cylinder heads undergo thermomechanical fatigue cycles associated with the engine start-stop cycle, leading to possible failure of thin sections in the cylinder heads that are exposed to steep thermal gradients such as the valve bridge area [3,6,7].…”

Section: Introductionmentioning

confidence: 99%

“…As the drive to advance the engine efficiency increases, the operating temperatures have kept increasing with the engine peak temperature reported well above 200 • C in recent times [3][4][5]. Cylinder heads undergo thermomechanical fatigue cycles associated with the engine start-stop cycle, leading to possible failure of thin sections in the cylinder heads that are exposed to steep thermal gradients such as the valve bridge area [3,6,7]. This problem is further aggravated with hybrid powertrains, as the number of such engine start-stop thermomechanical cycles are considerably increased.…”

Section: Introductionmentioning

confidence: 99%

“…Copper additions have been used in recent years to improve the high-temperature strength and the creep properties of the A356 alloy [1, 13,14]. The A356 + 0.5 wt % Cu alloy is commonly used in recent generations of cylinder heads [3,4,15]. The alloy is often heat-treated to an over-aged condition (T7) to improve the microstructural and dimensional stability of the component.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Strain Rate on the Deformation Behaviour of A356-T7 Cast Aluminium Alloys at Elevated Temperatures

Natesan

Ahlström

Manchili

et al. 2020

Metals

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Internal combustion engine downsizing and powertrain electrification trends in recent years have led to higher thermal loads on the cylinder head materials with an increased number of engine start–stop thermal load cycles. This requires designing cylinder heads that are resilient against thermomechanical fatigue damage. To reduce the developmental costs, reliable numerical models for use in computer-aided design approaches are required. Thus, a comprehensive understanding of the material deformation behaviour under loads mimicking in-service conditions is desired to make better engineering decisions. This study examines the effect of strain rate on the cyclic deformation behaviour of the A356-T7 + 0.5% Cu aluminium alloy commonly used in modern internal combustion engine cylinder heads. Samples extracted from the valve bridge areas of the cylinder heads are tested in strain-controlled fatigue tests. Samples are tested at strain rates of 1% s−1 and 10% s−1 at room temperature, 150 and 200 °C. The material exhibits increased isotropic hardening and softening rates and an increased number of cycles to failure at 10% s−1. The strain rate has a dramatic influence on the mean stress development at room temperature. The role of silicon particles in the fracture mechanism is investigated using electron microscopy techniques.

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A Comparative Investigation on the High Temperature Fatigue of Three Cast Aluminum Alloys

Cited by 13 publications

References 15 publications

Effect of Frequency, Environment, and Temperature on Fatigue Behavior of E319 Cast-Aluminum Alloy: Small-Crack Propagation

Effect of Frequency, Environment, and Temperature on Fatigue Behavior of E319 Cast-Aluminum Alloy: Small-Crack Propagation

Comparison of thermodynamic databases for 3xx and 6xxx aluminum alloys

Effect of Strain Rate on the Deformation Behaviour of A356-T7 Cast Aluminium Alloys at Elevated Temperatures

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