A critical review of experimental results and constitutive descriptions for metals and alloys in hot working

https://sistemas.eel.usp.br/docentes/arquivos/2166002/1234Nb/NiinomicitotoxicityTi-29Nb-13Ta-4,6Zr2003.pdf

Fatigue performance and cyto-toxicity of low rigidity titanium alloy, Ti–29Nb–13Ta–4.6Zr

Effect of inclusion on subsurface crack initiation and gigacycle fatigue strength

Hydrogen-assisted decohesion and localized plasticity in dual-phase steel

Fatigue life of additively manufactured Ti–6Al–4V in the very high cycle fatigue regime

In order to progress in the understanding of fatigue fracture process for high strength alloys, the previous studies of the subsurface fatigue crack generation are reviewed A change in crack initiation mechanism from specimen surface to specimen interior often introduces a plateau ("knee") followed by a rather sharp drop in the shape of S-N curve Various subsurface crack origins are related with microstructural crackings and pre-existing defects The subsurface initiation site is formed as a Stage I crack A new explanation of microcrack growth is proposed for the subsurface crack generation process The subsurface crack size is the most important parameter to determine how the crack becomes a fatal crack The size highly depends on the maximum cyclic stress range, which implies a ΔKth threshold controlling mechanism The dislocation structures in high-cycle fatigue are fairly planar for both austenitic steel and titanium alloy

Subsurface Crack Generation in High-cycle Fatigue for High Strength Alloys

Fabrication of Ni3Al thin foil by cold-rolling

The three-dimensional (3-D) distribution, morphology and nucleation site of intragranular ferrite formed in association with MnS particles were observed by computer-aided reconstruction of images obtained by serial sectioning in an Fe–0.1mass% C–1.5mass% Mn alloy isothermally reacted at 610 and 640 °C. 3-D analysis indicated that essentially all the intragranular ferrite precipitates nucleate at inclusions. The 3-D shape of idiomorphic ferrite precipitates was considerably more irregular than would be expected from their shape on polished specimen surfaces. Electron backscattering diffraction analysis showed that ferrite particles nucleated at inclusions were often composed of several grains and subgrains, and most of them were in contact with the surfaces of inclusions. Widmanstatten ferrite which grew radially from inclusions had a lath rather than a plate shape at the temperature studied.

Three-dimensional distribution, morphology, and nucleation site of intragranular ferrite formed in association with inclusions

Application of the Kocks–Mecking model to tensile deformation of an austenitic 25Cr–19Ni steel

Dislocation structures in warm-rolled low-carbon steels with ultrafine ferrite grains (∼1 μm) are analyzed by both transmission electron microscopy (TEM) observation and the modified Warren–Averbach procedures for X-ray diffraction profiles. In good accordance with the TEM observation results, the dislocation density is derived by the X-ray diffraction profile analysis to be 1.06×1014 and 1.98×1014 m−2, in the as-rolled 0.15C and 0.15C–0.1P steel, respectively. In contrast to the straight dislocation segments in the 0.15C steel, tangled and curved dislocations are observed in the phosphorus steel at both the as-rolled and annealed conditions. The larger q value and smaller dislocation arrangement parameter, M=R e ρ , are observed in the phosphorus steel. Phosphorus in the low-carbon steels tends to prompt the ratio of screw dislocation component and the dislocation arrangement with a stronger interaction during plastic deformation. Not only the dislocation density, but also the dislocation interaction behaviors control the changes of yield strength during annealing the as-rolled steels at 723 K. The modified Warren–Averbach X-ray diffraction profile analysis may be useful in characterizing the dislocation interaction behavior quantitatively.

Osamu Umezawa

Papers

Subsurface Crack Generation in High-cycle Fatigue for High Strength Alloys

Fabrication of Ni3Al thin foil by cold-rolling

Three-dimensional distribution, morphology, and nucleation site of intragranular ferrite formed in association with inclusions

Application of the Kocks–Mecking model to tensile deformation of an austenitic 25Cr–19Ni steel

Phosphorus-induced dislocation structure variation in the warm-rolled ultrafine-grained low-carbon steels