Direct observation and analysis of failure initiation and crack progression in tear toughness of two Al sheet alloys
Morgeneyer, T.F., Sinclair, I., Besson, J. and Starink, M.J. (2008) Direct observation and analysis of failure initiation and crack progression in tear toughness of two Al sheet alloys. In, Aluminium Alloys. 11th International Conference on Aluminium Alloys (ICAA 11) Weinheim, Germany, Wiley-VCH, 1504-1510.
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The failure initiation and crack progression in tear toughness tests on 2 sheet alloys have been analysed through synchrotron radiation computed tomography (SRCT), supported by TEM, SEM and DSC studies. For the quench sensitive 6156 Al-Mg-Si-Cu alloy propagation energy was reduced by changing water quench temperature from 20°C to 60°C. Observation of fail-ure initiation for a 60°C water quenched sample revealed failure ahead of the crack tip of grain boundaries oriented at 45° to the main loading axis and crack “tongues” extending into the material ahead of the main crack. The fracture toughness of AA2139 (Al-Cu-Mg-Ag) is anisotropic. SRCT reveals that three-dimensional distribution and morphology of pores and defects in the as-received state are anisotropic, with chains of voids and void elongation in the L (longitudinal) direction. For toughness testing in L-T orientation (T is transverse), voids ahead of the crack grow and link in the L direction. In T-L tests, voids ahead of the crack tip also grow in the loading direction. New models for crack propagation and toughness have been derived on the basis of the quantitative microstructural data.
|Item Type:||Book Section|
|Keywords:||aluminium, rolled, sheet, aerospace, toughness, crack, precipitation hardened, synchrotron radiation computed tomography, microtomography, precipitate free zone, crack propagation, quench sensitivity, anisotropy|
|Subjects:||T Technology > TN Mining engineering. Metallurgy|
|Divisions:||University Structure - Pre August 2011 > School of Engineering Sciences > Engineering Materials & Surface Engineering
|Date Deposited:||01 Jul 2008|
|Last Modified:||27 Mar 2014 18:35|
|RDF:||RDF+N-Triples, RDF+N3, RDF+XML, Browse.|
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