Effect of bimodal harmonic structure on fatigue properties of austenitic stainless steel under axial loading

Kikuchi, Shoichi; Nukui, Yuhei; Nakatsuka, Yuta; Nakai, Yoshikazu; Nakatani, Masashi; Kawabata, Mie; Ameyama, Kei

doi:10.1016/j.ijfatigue.2019.06.016

Cited by 22 publications

(9 citation statements)

References 51 publications

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“…Based on our prior work [39,40,41,42,43,44,45], a disk-shaped compact (DC(T)) sample type was employed in this work, similar to the specimen type referred to in the E399-17 ASTM standard. The composite was machined to produce specimens of this type having the sizes presented in Figure 1, after which the surfaces were polished to a mirror finish using emery papers (#80–#4000) followed by a suspension of SiO 2 .…”

Section: Methodsmentioning

confidence: 99%

Effect of TiB Orientation on Near-Threshold Fatigue Crack Propagation in TiB-Reinforced Ti-3Al-2.5V Matrix Composites Treated with Heat Extrusion

et al. 2019

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TiB-reinforced Ti-3Al-2.5V matrix composites, in which TiB whiskers are oriented parallel to the direction of heat extrusion, were fabricated via mechanical alloying and hot isostatic pressing (HIP). To investigate the near-threshold fatigue crack propagation in TiB-reinforced Ti-3Al-2.5V matrix composites, stress intensity factor K-decreasing tests were conducted for disk-shaped compact specimens having two different orientations of TiB whiskers at force ratios from 0.1 to 0.8 under ambient conditions. The crack growth rates, da/dN, for the composites incorporating TiB whiskers oriented perpendicular to the direction of crack growth were constantly lower than those obtained in the case where the orientation was parallel at the same stress intensity range ΔK, while the threshold stress intensity range, ΔKth, was higher. This effect can be explained by the increase in the degree of roughness-induced crack closure resulting from the perpendicular TiB, because fatigue cracks preferentially propagated across the boundaries between the matrix and the TiB in certain regions. In contrast, the effective threshold stress intensity range, ΔKeff,th, for composites was unaffected by the TiB orientation at low force ratios.

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Section: Methodsmentioning

confidence: 99%

Effect of TiB Orientation on Near-Threshold Fatigue Crack Propagation in TiB-Reinforced Ti-3Al-2.5V Matrix Composites Treated with Heat Extrusion

et al. 2019

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“…Nukui et al [72] found that the fatigue strength is increased because the resistance of the material to the initiation of fatigue cracks was improved by the grain refinement at the shell. The beginning of fatigue cracks was also observed in the coarse grains core in harmonic-structured designed materials, including CP titanium [72], Ti-6Al-4V alloys [73,74], and austenitic stainless steel [75,76]. However, in alloys, it can be attributed to both the network topology and strain-induced phase transformations, for example; α-fcc to ε-hcp in CCM [28].…”

Section: Fracture Behavior Of Hs Materialsmentioning

confidence: 96%

Harmonic Structure Design: A Strategy for Outstanding Mechanical Properties in Structural Materials

Sharma

Dirras

Ameyama

2020

Metals

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Structured heterogeneous materials are ubiquitous in a biological system and are now adopted in structural engineering to achieve tailor-made properties in metallic materials. The present paper is an overview of the unique network type heterogeneous structure called Harmonic Structure (HS) consisting of a continuous three-dimensional network of strong ultrafine-grained (shell) skeleton filled with islands of soft coarse-grained (core) zones. The HS microstructure is realized by the strategic processing method involving severe plastic deformation (SPD) of micron-sized metallic powder particles and their subsequent sintering. The microstructure and properties of HS-designed materials can be controlled by altering a fraction of core and shell zones by controlling mechanical milling and sintering conditions depending on the inherent characteristics of a material. The HS-designed metallic materials exhibit an exceptional combination of high strength and ductility, resulting from optimized hierarchical features in the microstructure matrix. The experimental and numerical results demonstrate that the continuous network of gradient structure in addition to the large degree of microstructural heterogeneity leads to obvious mechanical incompatibility and strain partitioning, during plastic deformation. Therefore, in contrast to the conventional homogeneous (homo) structured materials, synergy effects, such as synergy strengthening, can be obtained in HS-designed materials. This review highlights recent developments in HS-structured materials as well as identifies further challenges and opportunities.

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“…Indeed, the investigation of the fatigue behavior is one of the crucial aspects to probe before attempting any application as structural material. Therefore, several works have already been carried out to estimate the properties of materials tailored into harmonic structures under cyclic loading [20][21][22][23][24][25][26][27]. An increase of the fatigue endurance is reported, in line with the static tensile strength, despite the decrease of the fatigue stress intensity factor threshold.…”

Section: Introductionmentioning

confidence: 99%

Investigation on the Durability of Ti-6Al-4V Alloy Designed in a Harmonic Structure via Powder Metallurgy: Fatigue Behavior and Specimen Size Parameter Issue

Guennec

Ishiguri

Kawabata

et al. 2020

Metals

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In the present work, the four-point bending loading fatigue properties of a heterogeneously distributed grain size microstructure consolidated from Ti-6Al-4V alloy powder are studied. The microstructure involved here, a so-called “harmonic structure”, possesses quasi-spherical large grain regions (“cores”) embedded in a continuous fine grain region (“shell”). Unlike the previous reports dealing with this issue, the effect of the specimen size on the fatigue characteristics is also probed, since two distinct specimen configurations are considered. Furthermore, the obtained experimental data are compared with the corresponding fatigue results derived from homogeneous coarse grain counterparts. Contrary to homogeneous structure material, discrepancies on both the fatigue strength and the fatigue crack initiation aspects are found for the harmonic structure material. Consequently, the present work aims to clarify the underlining phenomena involved in the specimen size effect detected for Ti-6Al-4V designed in the harmonic structure. A less active interface surface between the core and the shell combined with a wider critical volume in the large size specimen should be the main reasons of the fatigue strength discrepancy.

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Effect of bimodal harmonic structure on fatigue properties of austenitic stainless steel under axial loading

Cited by 22 publications

References 51 publications

Effect of TiB Orientation on Near-Threshold Fatigue Crack Propagation in TiB-Reinforced Ti-3Al-2.5V Matrix Composites Treated with Heat Extrusion

Effect of TiB Orientation on Near-Threshold Fatigue Crack Propagation in TiB-Reinforced Ti-3Al-2.5V Matrix Composites Treated with Heat Extrusion

Harmonic Structure Design: A Strategy for Outstanding Mechanical Properties in Structural Materials

Investigation on the Durability of Ti-6Al-4V Alloy Designed in a Harmonic Structure via Powder Metallurgy: Fatigue Behavior and Specimen Size Parameter Issue

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