Quantification of the interaction within defect populations on fatigue behavior in an aluminum alloy

✍ Scribed by P. Li; P.D. Lee; D.M. Maijer; T.C. Lindley

• Publisher: Elsevier Science
• Year: 2009
• Tongue: English
• Weight: 806 KB
• Volume: 57
• Category: Article
• ISSN: 1359-6454
• DOI: 10.1016/j.actamat.2009.04.008

✦ Synopsis

The interaction between fatigue crack evolution and porosity in A356-T6 alloys was characterized using both X-ray microtomography and finite-element analysis. The formation and propagation of fatigue cracks are dominated by the highest local stress-strain concentration (k

) caused by the presence of porosity adjacent to the free surface and the crack tip, respectively. The k g factor proved to be a suitable parameter to quantify the influence of porosity on fatigue cracking and to predict the fatigue crack growth rate (da=dN ). Although microporosity has a complex, tortuous morphology, a simple method for mapping the shape to an idealized sphere was proposed. It was found that using a sphere with equal projected area in the plane normal to the loading direction was a good approximation, allowing an equivalent k g to be calculated.