ISSN:
1573-9325
Keywords:
cyclic loading
;
frequency
;
damage accumulation
;
fatigue crack
;
plastic-deformation zone
;
dislocation structure
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract We examine the dislocation structure of a pseudo-α-alloy of the Ti–Al–Zr–Sn–Mo–Nb–Si system upon fatigue and cyclic crack-resistance testing under identical conditions of symmetrical tensile–compressive loading with a frequency of 100, 500, 3000, and 10,000 Hz. It is shown that the structural development of the alloy during the fatigue-damage accumulation occurs in a limited number of microvolume zones near local stress concentrators, although a considerable number of structural alteration zones originate but stay undeveloped, while the rest of the material remains almost unchanged. At the stage of main-crack development, the structure of the crack-tip plastic zone presents a further logical development of the structure that was formed during the fatigue-damage accumulation. However, the stress level, which is much higher than that in the bulk volume of the material, can be responsible for additional structural elements and a diminishing role of local stress concentrators. These mechanisms are true for the entire range of cyclic loading frequencies studied. A variation of the rate of cyclic loading leads only to a slight decrease in the size of the microvolumes of maximum structural changes during fatigue-damage accumulation and in the honeycomb structural elements during the main crack propagation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1005260500863
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