Journal ArticleDOI
Fatigue properties of ultrafine grained low carbon steel produced by equal channel angular pressing
TLDR
In this article, the effect of load ratio on the fatigue crack growth rates of ultra-fine grained microstructure was investigated, and the results indicated that the contribution of the crack closure vanished.Abstract:
Ultrafine grained low carbon (0.15 wt.% C) steel produced by equal channel angular pressing (ECAP) was tested for investigating fatigue properties, including cyclic softening and crack growth rate. Emphasis was placed on investigating the effect of load ratio on the fatigue crack growth rates of ultrafine grained microstructure. The ECAPed steel exhibited cyclic softening. After the first cycle, the tension and compression peak stresses decreased gradually with the number of cycles. Fatigue crack growth resistance and the threshold of ECAPed ultrafine grained steel were lower than that of an as-received coarse grained steel. This was attributed to a less tortuous crack path. The ECAPed steel exhibited slightly higher crack growth rates and a lower ΔKth with an increase in R ratio. The R ratio effect on growth rates and ΔKth was basically indistinguishable at a lower load ratio (R>0.3) compared with other alloys, indicating that the contribution of the crack closure vanished. This was explained by the fact that finer grained materials produce a lower opening load Pop due to a relatively less serrated crack path. Consequently, Kmin can reach Kop readily with a smaller increment of load ratio. The crack growth rate curve for the ECAPed ultrafine grained steel exhibited a linear extension to the lower growth rate regime than that for the coarse grained as-received steel. This behavior can be explained by a reverse crack tip plastic zone size (rp) that is always larger than the grain size.read more
Citations
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Mechanical properties of nanocrystalline materials
TL;DR: The mechanical properties of nanocrystalline materials are reviewed in this paper, with emphasis on their constitutive response and on the fundamental physical mechanisms, including the deviation from the Hall-Petch slope and possible negative slope, the effect of porosity, the difference between tensile and compressive strength, the limited ductility, the tendency for shear localization, fatigue and creep responses.
Journal ArticleDOI
Cyclic deformation and fatigue properties of very fine-grained metals and alloys
TL;DR: In this paper, the authors present a review of the literature on the fatigue properties of very fine-grained bulk materials and their applications in the last decade, focusing on simple materials and on more complex alloys and structural materials.
Journal ArticleDOI
Failure of metals III: Fracture and fatigue of nanostructured metallic materials
TL;DR: In this article, the current state of the art in terms of plastic localization, damage, static and fatigue cracking for three classes of systems: (1) bulk ultra-fine grained and nanocrystalline metals, (2) thin metallic films on substrates, and (3) 1D and 2D freestanding micro and nanoscale systems.
Journal ArticleDOI
Fatigue properties and crack behavior of ultra-fine and nanocrystalline pure metals
TL;DR: In this paper, the fatigue properties of pure metals (Al, Ti, Ni and Cu) produced via equa-channel angular pressing (ECAP) are analyzed by means of stress-controlled tests and the results compared with those of the micro-crystalline counterpart.
Journal ArticleDOI
Fatigue limit and crack growth in ultra-fine grain metals produced by severe plastic deformation
TL;DR: In this paper, the experimental results on fatigue resistance of ultra-fine grain metals produced by severe plastic deformation (SPD) are reviewed with regard to two major characteristics of cyclic damage initiation and failure.
References
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Book
Fatigue of materials
TL;DR: In this article, the cyclic deformation and fatigue crack initiation in polycrystalline ductile solids was studied and a total-life approach was proposed to deal with the problem.
Journal ArticleDOI
Fatigue crack closure under cyclic tension
TL;DR: In this article, an analysis of the stress distribution acting on the fracture surfaces shows that the local compressive stress maxima may exceed the yield stress of the material and that crack closure may influence the shape of the striation pattern.
Journal ArticleDOI
Effect of load ratio and maximum stress intensity on the fatigue threshold in Ti–6Al–4V
Brad L. Boyce,R.O. Ritchie +1 more
TL;DR: In this paper, the authors examined the effect of a wide range of loading frequencies and load ratios on fatigue-crack propagation and threshold behavior in a Ti-6Al-4V turbine blade alloy consisting of ∼60 vol% primary-α and ∼40 vol% lamellar α+β.
Journal ArticleDOI
Overview of fatigue performance of Cu processed by severe plastic deformation
TL;DR: In this paper, discrepancies regarding cyclic softening of Cu processed by severe plastic deformation (SPD) were investigated, and all samples softened if the microhardnesses before and after fatiguing are compared.
Journal ArticleDOI
Microstructural changes in equal channel angular pressed low carbon steel by static annealing
TL;DR: In this paper, the thermal stability of ultrafine grained low carbon steel manufactured by the equal channel angular pressing technique was examined by imposing the static annealing treatment for 1h at various temperatures of 693-873 K.