Isothermal fatigue damage mechanisms at ambient and elevated temperature of a cast Al-Si-Cu aluminium alloy. (April 2019)

• Record Type: Journal Article
• Authors: Wilson, Pablo; Saintier, Nicolas; Palin-Luc, Thierry; Bergamo, Sebastien
• Is Part Of: International journal of fatigue. Volume 121(2019)
• Page Start: 112
• Page End: 123
• Publication Date: 2019-04
• Subjects: Aluminum alloys -- Low-cycle fatigue -- High temperature testing -- Tomography -- Casting defects; Materials -- Fatigue -- Periodicals; Materials -- Fatigue; Periodicals; 620.1122
• DOI: 10.1016/j.ijfatigue.2018.11.016
• Languages: English
• ISSNs: 0142-1123

Abstract

Highlights: Cracks initiate on casting defects at low and high temperature. Eutectic regions play a larger role on the crack propagation path as temperature increases. Defects interact and influence the fatigue crack path. Real size and location of defects has to be considered in order to assess the defect criticity. LCF life and crack growth can be adressed with a crack-like defect approach effectively predicted. Abstract: Cast aluminium alloys have a key position as structural materials for the automotive industry combining good mechanical performance, excellent castability and thermal conductivity, making them a suitable choice for engine parts such as cylinder heads. In this paper, the low-cycle fatigue behaviour of a cast aluminium alloys is investigated at ambient and elevated temperatures by the use of in situ optical surface crack monitoring, secondary electron microscopy and X-ray tomography which are combined to study the fatigue mechanisms. The observations highlight the effect of defect distribution and temperature on the crack propagation path and in particular the change of the role of eutectic regions as the temperature increases. In addition, based on the defects population analyses by tomography, a fatigue crack initiation model is proposed to consider both temperature and defect effects on the total low-cycle fatigue life and fatigue crack growth rates.