Abstract
The article deals with microstructure and fatigue properties of machinable AA2007-T2 and AA2015-T2 aluminium alloys. The extruded and drawn rods of diameter of 19 mm were used for fatigue tests. Rods were manufactured in the plant of ALCAN Děčín, Ltd. by an usual production method. The process of fatigue crack initiation and growth was qualitatively identical for both alloys. The fatigue crack initiation took place on the surface of test body notches, followed by crystallographic and striation phases of fatigue crack growth with the final plastic rupture. Fatigue lifetimes of the AA2015-T2 alloy compared to the AA2007-T2 alloy were higher in the whole tested area of cyclic stresses. This was caused by the higher share of hard brittle particles containing Fe in the AA2007-T2 alloy, which resulted in an easier initialisation of fatigue cracks and accelerated propagation. The higher content of low-melting metals and higher area share of soft particles of low-melting metals in the AA2015-T2 alloy, compared to the AA2007-T2 alloy, did not adversely affect the alloy fatigue performance.

Key words
machinable aluminium alloys, microstructure, fatigue test, fractographic analysis, mechanisms of fatigue crack growth

Full text (627 KB)