Influence of Creep and Subsequent Heat Treatment of AK4-1 (Al-Cu-Mg) Alloy Specimens on Fatigue Resistance
A.Yu. Larichkin1, K.V. Zaharchenko1, V.I. Kapustin2
1Lavrentyev Institute of Hydrodynamics SB RAS, Novosibirsk, Russia
2Novosibirsk State Technical University, Novosibirsk, Russia
Keywords: aluminum alloy, elastoplastic deformation, deformation characteristics, creep, fatigue failure
Abstract
Physical modeling of the forming process of a panel made of AK4-1 (Al-Cu-Mg) alloy under creep conditions at an annealing temperature of T = 420 °C was carried out. The forming process was simulated by tensile creep of cylindrical specimens to various strain values not exceeding 6 %. The tests yielded parameters of the classical Boyle-Norton model for steady-state creep. In accordance with the technological forming process under creep conditions, heat treatment (quenching and aging) was performed to restore the panel’s strength properties. Stress levels for fatigue tests were determined using stepwise cyclic loading with increasing stress amplitude. Tests were stopped upon the occurrence of plastic deformations. A comparison of fatigue resistance characteristics was performed for as-received specimens, specimens stretched under creep, specimens after heat treatment, and specimens with zero creep strain after heat treatment. It was shown that accumulated creep strain exceeding 2 % can reduce the fatigue performance compared to as-received specimens.
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