DOI: 10.36347/sjet.2019.v07i01.004

Pages: 18-26

In this paper, the fatigue strength of casted aluminum alloys A14 and A17, AK9M2 and AK8M3 was investigated at room elevated temperatures of (20 °C-1550C-2700C-3400C and 200-1000-2000-2500C) and at different frequencies (0.3KHz,3.0KHz,9KHz and 18KHz) and various loading bases(1.106, 5.106 and 1.107 cycles). Experimental studies were performed at different frequencies on primary aluminum alloys Al4, Al7 and on AK9M2 and AK8M3 as model materials for establishing the influence of high test temperatures on the behavior of endurance limits, and the influence of frequency of alternating bending on the kinetics of micro -hardness, and dislocation density on fatigue characteristics. In addition, the character of the dependencies obtained confirms the possibility of using accelerated fatigue tests by increasing the frequency for aluminum casting alloys made using recycled materials as well. The influence of amplitude-frequency and time parameters on the kinetics of physical-mechanical properties demonstrate that the most intensive changes in structure-sensitive characteristics for the selected levels of variable stresses occur during early stages of cyclic loading. It was confirmed by the results of fatigue tests of the deformable aluminum alloys. The experiments show that the shape of fatigue curves does not change with increasing frequency. Fatigue curves for different frequencies are practically equidistant. All studies materials are characterized by a monotonous increase in the fatigue life with increasing loading frequency, which is observed under alternating bending conditions for various test bases. The analysis of results of experiments demonstrated that the established endurance limits also increase with increasing frequency. The test results demonstrate that the loading frequency significantly influences fatigue life of all studied materials.