An investigation of the fatigue properties of the aluminium-copper alloy AA2014-T6

ABSTRACT

An approach to determine the fatigue behaviour in the heat-affected zone (HAZ) of AA 2014 has not been investigated exhaustively since the HAZ has been treated as one region. In this study, fatigue crack growth (FCG), fatigue strength and low cycle fatigue (LCF) properties of the base metal (BM) and two regions of the HAZ were studied. The two regions of the HAZ were thermally simulated at 590°C and 650°C representing regions of the weldment 4 mm and 5 mm from the weld centreline respectively. The hardness tests and microstructure characterisation of the base metal and the two regions of the HAZ were also carried out. The HAZ region thermally simulated at 590°C was found to offer the least resistance to FCG, had shorter LCF life and lowest value of fatigue strength compared to both the BM and the HAZ region thermally simulated at 650°C. The cause of weakness in this region was associated with the dissolution of strengthening phases. The degradation of the fatigue properties of AA2014 occurred severely at 590°C due to the dissolution of CuAl₂ precipitates in the aluminium matrix. The HAZ region thermally simulated at 590°C was confirmed to be the weakest link in the HAZ.

KEYWORDS:

• AA2014
• fatigue crack growth
• fatigue strength
• low cycle fatigue
• thermal simulation
• heat-affected zone

Acknowledgments

The authors wish to acknowledge the University of Nairobi for granting permission to access its workshop and laboratories at the Department of Mechanical and Manufacturing Engineering.

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No potential conflict of interest was reported by the author(s).

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Funding

Funding The author(s) reported there is no funding associated with the work featured in this article.