G.O. Rading, M. Shamsuzzoha and J.T. Berry "A TEM and High Resolution Microstructural Characterization of the Al-Li-Cu Alloy 2095 in the T8 Temper Condition" ACEM-13: 13th. Conf. Australian Society for Electron Microscopy, Brisbane (1994)

Citation:
O PROFRADINGGEORGE. "G.O. Rading, M. Shamsuzzoha and J.T. Berry "A TEM and High Resolution Microstructural Characterization of the Al-Li-Cu Alloy 2095 in the T8 Temper Condition" ACEM-13: 13th. Conf. Australian Society for Electron Microscopy, Brisbane (1994).". In: Mountain Research and Development, vol. 8, no. 2. 2011; 1994.

Abstract:

The fatigue crack growth (FCG) characteristics of a cast Al-Cu alloy A206 in the T7 temper condition were studied in laboratory air at a frequency of 30 Hz and an R-ratio of 0.2. Two different (as cast) thicknesses and two different casting conditions (casting with and without a chill) were investigated with the aim of characterizing the effect of porosity on the FCG behavior. The level of porosity in each sample was determined by the point-counting method and varied from 2.4 to 4.0% before hot isostatic pressing (HIP).<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

 

The study covered both near-threshold and mid-range regimes of FCG. The results indicate that for this limited range of porosity, there exists no systematic relationship between casting conditions (i.e., chilled or non-chilled) or the as-cast thickness and the average level of porosity. However, in the near-threshold regime, the FCG resistance decreased as the level of porosity increased, while in the mid-range of FCG, the FCG rate was fairly independent of the amount of porosity.

Application of HIP led to a reduction in the porosity level from about 4% to less than 0.4%, but this was accompanied by improvement in the FCG resistance only, close to the threshold. The results are rationalized in terms of the effect of porosity on the micro-mechanisms of fatigue crack growth and the initiation of secondary cracks caused by the size, distribution and morphology, of the pores.

Notes:

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