Ductile-Brittle Transition in Refractory Metal Alloys Containing a Dispersed Second Phase

Trefilov, V. I.; Pokhodnya, I. K.; Moiseev, V. F.; Vasiliev, Andrei

doi:10.1515/9783112501740-051

Cited by 2 publications

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“…For As15-6 ceramics the porosity does not exceed 1%, and the pores have a rounded shape, which also reduces the stress concentration in the volume (figure 6). Analysis of the structure of ceramic materials BO-13, BOK-60, BOK-71 and ONT-20 using electron microscopy shows that this class of instrumental materials can be considered as dispersionhardened materials [21]. Depending on the brand of ceramics, its matrix is hardened with particles of oxides, carbides (TiC, TiN, ZrO 2 , etc.).…”

Section: Resultsmentioning

confidence: 99%

Special features of manufacturing cutting inserts from nanocomposite material Al₂O₃-SiC

et al. 2021

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The article examines the cutting characteristics of the developed composite material based on aluminum oxide micropowders with silicon carbide nanopowder additives obtained with the help of electric sintering. The influence of thermal conductivity of the developed composite Al2O3-SiC based material on the wear and durability of the material in application of cutting tool is examined, and a comparison with the traditional cutting ceramic tool materials is made. Considering that the process of cutting with ceramic inserts is carried out without the cutting fluids, the heat removal improvement from the cutting zone makes it possible to increase the tool life. It is proposed to use the thermomechanical parameter B for a comparative assessment of cutting ceramic composite material characteristics.

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Section: Resultsmentioning

confidence: 99%

Special features of manufacturing cutting inserts from nanocomposite material Al₂O₃-SiC

et al. 2021

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“…В этом состоянии на диаграммах деформации в прямом и обратном направлении (как в верхнем, так и в нижнем сечении) уровень напряжения примерно соответствует определению материала как циклически стабильного, но не соответствует такому определению, если судить по амплитуде деформации для нижнего сечения. Иначе говоря, многократное циклическое знакопеременное нагружение не ликвидирует полностью начальную анизотропию материала 4 .…”

Section: экспериментальные данные для образца № 25 и их анализunclassified

“…Это означает циклическое упрочнение материала данного образца в указанном направлении, и в этом состоит еще одно отличие его поведения от поведения образца №22 (как циклически стабильного при первом цикле нагружения). 4 Это объясняется наличием изотропной составляющей упрочнения [38]. На основе численных экспериментов по многократному (циклическому) деформированию показано, что с увеличением количества циклов практически исчезает площадка текучести [39].…”

Section: экспериментальные данные для образца № 11 и их анализunclassified

“…Обобщенная схема деформационного упрочнения материала (в том числе «скрытого» под площадкой текучести) представлена в обзоре [3] (диаграмма на рис. 10 [3], полученная в работе [4] на основе установленных различных типов дислокационных структур). На этой диаграмме выделен, в частности, предел упругости, который определяется при наличии начальной линейной стадии упрочнения (наблюдаемой за площадкой текучести) путем ее экстраполяции на нулевую деформацию.…”

Section: Introductionunclassified

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About the Yield Plateau Under Sign-Variable Loading

Rychkov

Goncharova

Rezin

2021

PNRPU Mechanics Bulletin

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During tension of samples of low-carbon steels and some other plastic materials, the sharp yield point and the yield plateau are fixed on the deformation diagram. In this case, Chernov-Luders bands appear on the surface of the sample in the local section, which then propagate along the tension axis. The physical nature of the sharp yield point is established: the drop in the load after reaching the (upper) yield limit occurs as a result of dislocations being an extraction out of the cloud of the embedded atoms and vacancies (Cottrell's cloud). At the occurrence of the sharp yield point , the plastic strain is limited to a small area. When the sample deformation increases, the plasticity zone (the yield plateau is marked on the diagram at this time) expands, and the stress-strain state in this zone becomes almost homogeneous, if we do not consider its boundary with the elastic region. At the end of the yield plateau, the entire sample experiences a uniform plastic deformation, excluding its ends (galtels). From this point on, the strain diagram shows the of material hardening; presumably, this hardening occurred from the very beginning, but was hidden under the yield plateau. This is evidenced by the resulting strain-induced anisotropy. After unloading the sample, when the plastic strain front (in the form of Chernov-Luders bands) has not yet passed through the entire sample, and the Bauschinger's effect is observed with the subsequent change in the stress sign. The fact that after the occurrence of the sharp yield point , the plastic strain is not localized in a certain volume, similar to what occurs during the neck formation, but spreads along the sample, serves as proof of the material hardening due to plastic deformation immediately after the load falls. Therefore, if the plastically deformable part of the sample did not have a hardening of the material due to the plastic strain growth, it would not be able to spread to the elastic part of the sample. This paper presents the experimental data of the sign-variable torsion of the thin-walled tubular samples of steel 45 in the annealed state. The deformation atdiagram of the occurrence and development of the yield plateau in distinct sections along the length of the test sample is obtained. The material hardening diagram hidden under the yield plateau is reconstructed using the well-known Masing's principle.

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Ductile-Brittle Transition in Refractory Metal Alloys Containing a Dispersed Second Phase

Cited by 2 publications

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Special features of manufacturing cutting inserts from nanocomposite material Al₂O₃-SiC

Special features of manufacturing cutting inserts from nanocomposite material Al₂O₃-SiC

About the Yield Plateau Under Sign-Variable Loading

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Ductile-Brittle Transition in Refractory Metal Alloys Containing a Dispersed Second Phase

Cited by 2 publications

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Special features of manufacturing cutting inserts from nanocomposite material Al2O3-SiC

Special features of manufacturing cutting inserts from nanocomposite material Al2O3-SiC

About the Yield Plateau Under Sign-Variable Loading

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Special features of manufacturing cutting inserts from nanocomposite material Al₂O₃-SiC

Special features of manufacturing cutting inserts from nanocomposite material Al₂O₃-SiC