Characterisation of Al-Cu and Al-Mg-Si Free-Cutting Alloys

Miroslav Karlík; Jiri Faltus; Jitka Nejezchlebová; Petr Haušild; Petr Harcuba

doi:10.4028/www.scientific.net/MSF.794-796.1181

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HomeMaterials Science ForumMaterials Science Forum Vols. 794-796Characterisation of Al-Cu and Al-Mg-Si...

Characterisation of Al-Cu and Al-Mg-Si Free-Cutting Alloys

Abstract:

Free cutting alloys of Al-Cu (AA2011 and AA2111B) in T6 temper and Al-Mg-Si system (AA6023 and AA6262) in tempers T6 and T8 were subjected to Charpy U - notch impact testing at the temperatures ranging from 20°C to 350°C. The microstructure of the materials was characterized by light metallography, fracture surfaces were observed using scanning electron microscope (SEM). The alloys showed a significant decrease in the impact energy KU at temperatures ~125°C (AA2011, AA2111B), ~170°C (AA6023), and ~250°C (AA6262), respectively. This decrease of KU was caused by melting of disperse phases containing low-melting point metals (Pb, Sn, Bi), which was confirmed by differential scanning calorimetry. Additional annealing of the AA6262-T8 alloy for 2h at 400°C followed by slow cooling led to the transformation of Pb + Bi particles accompanied by the shift of the melting temperature from ~250 to ~310 °C. Higher temperature solution annealing of the AA6023 alloy for 30 min at 540°C (as a replacement of common 30 min at 520°C) resulted in a partial transformation of Sn + Bi particles accompanied by melting point shift from ~170 to ~200°C. Chemical composition of the corresponding phases was monitored by energy dispersive X-ray spectroscopy in SEM.

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Periodical:

Materials Science Forum (Volumes 794-796)

Pages:

1181-1186

DOI:

https://doi.org/10.4028/www.scientific.net/MSF.794-796.1181

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Online since:

June 2014

Authors:

Miroslav Karlík*, Jiri Faltus, Jitka Nejezchlebová, Petr Haušild, Petr Harcuba

Keywords:

Differential Scanning Calorimetry (DSC), Liquid Metal Embrittlement, Mechanical Property, Metallography

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