The effect of silicon content on long crack fatigue behaviour of aluminium-silicon piston alloy at elevated temperatures


Moffat, A.J., Barnes, S., Mellor, B.G. and Reed, P.A.S. (2005) The effect of silicon content on long crack fatigue behaviour of aluminium-silicon piston alloy at elevated temperatures. International Journal of Fatigue, 27, (10-12), 1564-1570. (doi:10.1016/j.ijfatigue.2005.06.023).

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Description/Abstract

The microstructure of aluminium piston alloys comprises primary and eutectic silicon together with numerous intermetallics. Previous research has shown that primary silicon strongly influences both fatigue crack initiation and subsequent propagation behaviour, however, the detailed effects of varying silicon volume fraction and morphology have not been fully addressed. Therefore, the fatigue properties of a number of candidate piston alloys with varying volume fractions of silicon have been studied. Long crack fatigue tests have been performed at room and elevated temperature typical of the gudgeon pin boss (200 8C) using a test frequency of 15 Hz (a typical engine frequency at engine idle condition). Microstructural characterisation using image analysis approaches combined with optical profilometry has been used to assess the fracture surfaces of test samples. The role of primary Si in enhancing crack growth rates at high DK levels, whilst affording improvements in crack growth rates at lower DK levels due to local crack deflections and shielding, has been confirmed. In the absence of primary Si (lower Si content alloys) the low DK level crack growth behaviour is dominated by matrix properties (intra-dendritic crack growth pre-dominates) whilst the high DK level crack growth behaviour is inter-dendritic and occurs along the weak path of the eutectic Si and/or intermetallic network.

Item Type: Article
Additional Information: Fatigue Damage of Structural Materials V. Hyannis, MA, USA 19-24 September 2004, edited by M. Bache, R. Holtz, T. Nicholas, P. Paris and A. Vasudevan
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Keywords: aluminium–silicon, long crack fatigue, piston, micro-mechanisms
Subjects: T Technology > TJ Mechanical engineering and machinery
T Technology > TN Mining engineering. Metallurgy
Divisions: University Structure - Pre August 2011 > School of Engineering Sciences > Engineering Materials & Surface Engineering
ePrint ID: 65440
Date Deposited: 13 Feb 2009
Last Modified: 27 Mar 2014 18:46
Contact Email Address: pasr1@soton.ac.uk
URI: http://eprints.soton.ac.uk/id/eprint/65440

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