Journal ArticleDOI
Influence of loading frequency on high cycle fatigue properties of b.c.c. and h.c.p. metals
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In this article, the influence of the loading frequency on the high cycle fatigue properties of two b.c.p. metals, commercially pure (c. p.) niobium and c. p. tantalum, in annealed and cold worked condition, and of two annealing h.c.p. titanium and of Ti-6Al-7Nb alloy were investigated.Abstract:
The influence of the loading frequency on the high cycle fatigue properties of two b.c.c. metals, commercially pure (c.p.) niobium and c.p. tantalum in annealed and cold worked condition, and of two annealed h.c.p. titanium and of Ti–6Al–7Nb alloy were investigated. Endurance data in the regime of 105 to 2×108 cycles to failure obtained with rotating bending and ultrasonic fatigue testing equipment (loading frequencies 100 Hz and 20 kHz, respectively) coincide within the ranges of scatter for niobium and Ti–6Al–7Nb alloy. The mean endurance limits at 2×108 cycles of these metals are ≈60% of the respective yield stress of the as produced material. The high loading frequency leads to prolonged lifetimes and increased mean endurance limits for tantalum and (less pronounced) for titanium. Fatigue crack initiation in tantalum changes from a preferentially ductile and transgranular mode at 100 Hz to a more brittle, crystallographic and intergranular mode at 20 kHz. The mean endurance limit of tantalum is above the yield stress of the as produced material, and high initial rates of plastic deformation therefore result. Cold working of tantalum and niobium improves their static strength properties, but is of only minor importance for the high cycle fatigue behaviour.read more
Citations
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Journal ArticleDOI
Very high cycle fatigue measuring techniques
TL;DR: In this paper, the principles and testing procedures of very high cycle fatigue tests and reports findings in the areas of crack formation, non-propagating small cracks, long crack propagation and thresholds are reported.
Journal ArticleDOI
Microstructural Influences on Very-High-Cycle Fatigue-Crack Initiation in Ti-6246
Christopher J. Szczepanski,Christopher J. Szczepanski,Sushant K. Jha,J. M. Larsen,J. W. Jones +4 more
TL;DR: In this article, the authors examined the mechanisms of fatigue-crack formation by quantifying critical microstructural features observed in the fatiguecrack initiation region, and found that the fracture surface near the fatigue crack-initiation site was crystallographic in nature.
Journal ArticleDOI
Recent developments in ultrasonic fatigue
TL;DR: The recently increased interest in very high cycle fatigue properties of materials has led to extended use and further development of the ultrasonic fatigue testing technique as discussed by the authors, where the high frequency allows collecting lifetime data of up to 1010 cycles and measuring crack propagation rates down to 10−12m per cycle within reasonable testing times.
Journal ArticleDOI
Fatigue and fatigue crack growth of aluminium alloys at very high numbers of cycles
TL;DR: The application of ultrasonic frequency (20 kHz) loading to test fatigue and fracture mechanical properties of materials is briefly reviewed and recent investigations on high strength aluminium alloys are reported as mentioned in this paper.
References
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Journal ArticleDOI
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H. Zitter,Hanns Plenk +1 more
TL;DR: It seems that simple and cheap electrochemical tests allow an even more precise differentiation of the suitability of metallic materials for implant purposes than most of the conventional implantation tests, considering that biocompatibility is not only determined by corrosion products, but also by exchange currents and reaction products of redox processes involving tissue compounds.
Journal ArticleDOI
Cyclic deformation and fatigue behaviour of α-iron mono-and polycrystals
Haël Mughrabi,K. Herz,X. Stark +2 more
TL;DR: In this paper, a series of cyclic deformation tests were conducted at room temperature on decarburized high-purity α-iron specimens in mono and polycrystalline form.
Journal ArticleDOI
Fatigue crack growth and threshold measurements at very high frequencies
TL;DR: In this article, a survey of fatigue investigations of metallic materials, composites, metallic glass, and ceramics, determined with the ultrasound method, is presented, emphasizing the influences on dislocation structures, crack initiation, and fatigue crack growth for pure metals and for technical materials.
Journal ArticleDOI
The cyclic stress-strain response of copper at low strains—i. Constant amplitude testing
TL;DR: In this paper, the cyclic stress-strain (CSS) curve for polycrystalline copper can be correlated with that for monocrystals, particularly in showing a plateau and a fatigue limit at an equivalent stress and strain (equivalence being expressed via Taylor's factor).