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Using a direct proportionality between the rate of fatigue crack growth and crack opening displacement above a threshold, it is shown that fatigue crack growth data for a wide variety of different materials can be accurately described in terms of the mechanical properties and two material constants ; the constant of proportionality A and the threshold stress intensity factor Kth. Some 65 sets of data for tests at R ~ 0 were analysed by computer and it is shown that the approach is valid to growth rates up to about 10 .4 in]cycle, i.e. until the onset of crack propagation by dimple formation. It is found that A can be related to the yield strain for crack growth in non-aggressive environments, and is in r creased by increasingly severe environments, while Kt~ is decreased. These changes provide a measure of the severity of the environment. Crack growth rate in non-aggressive environments is shown to be independent of the yield stress and proportional to the strain intensity factor above the threshold. The tabulation of A and Kth values as a function of material, environment and loading conditions provides a systematic engineering approach to estimating rates of fatigue crack growth and in determining the residual lifetimes of flawed structures.

Parent bore materials of copper-containing hypereutectic Al-Si alloys have been tried with limited success. Fundamentally the reason for this technology limitation is because coppercontaining hypereutectic aluminum-silicon alloys precipitate the copper-phase late in the solidification process and hinder the feeding process to make sound castings. As a result, the copper-containing hypereutectic Al-Si alloys that have been used in the past as parent bore materials have been compromises of low silicon content, which has translated into low wear resistances and the need for special surface treatments. This paper presents the new advancements to the old hypereutectic aluminum-silicon technology for linerless parent bore aluminum blocks. The technology is centered around the use of a copper-free hypereutectic aluminum-silicon alloy parent bore material and a piston coating that has particles of a solid lubricant embedded in the plated coating. Because there are no commercially available copper-free hypereutectic aluminum-silicon alloys, this paper contains the thermal/physical/mechanical data for such alloys.

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Lost foam casting is a sand casting process in which the mold consists of an evaporative polystyrene foam pattern embedded in sand. It is especially well suited for making complex parts with convoluted features such as engine blocks, transmission cases, and cylinder heads. This article describes the lost foam casting process and its primary advantages, including the elimination of flash and parting lines, the relative ease of prototyping with foam, and the ability to incorporate multiple metals, whether in sections or layers, through sequential pours. It illustrates an entire process cycle from mold filling to fusion, cooling, and part ejection. The article also provides information on casting quality, discussing dimensional tolerances, fold defects, and porosity.