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Crystal Lattice Rotations Induced by Shear Banding in fcc Metals Deformed at High Strain Rates

Mania Izabela, Paul Henryk, Chulist Robert, Petrzak Paweł, Miszczyk Magdalena, Prażmowski Mariusz

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 1

319--329

EN

In this paper, the microstructural and texture changes in polycrystalline CuZn30 alloy, copper, and AA1050 aluminium alloy have been studied to describe the crystal lattice rotation during shear bands formation. The hat-shaped specimens were deformed using a drop-hammer at the strain rate of 560 s-1. Microstructure evolution was investigated using optical microscopy, whereas texture changes were examined with the use of a scanning electron microscope equipped with the EBSD facility. The microstructural observations were correlated with nanohardness measurements to evaluate the mechanical properties of the sheared regions. The analyses demonstrate the gradual nature of the shear banding process, which can be described as a mechanism of the bands nucleation and then successive growth rather than as an abrupt instability. It was found that regardless of the initial orientation of the grains inside the sheared region, a well-defined tendency of the crystal lattice rotation is observed. This rotation mechanism leads to the formation of specific texture components of the sheared region, different from the one observed in a weakly or non-deformed matrix. During the process of rotation, one of the {111} planes in each grain of the sheared region ‘tends’ to overlap with the plane of maximum shear stresses and one of the <110> or <112> directions align with the shear direction. This allows slip propagation through the boundaries between adjacent grains without apparent change in the shear direction. Finally, in order to trace the rotation path, transforming the matrix texture components into shear band, rotation axis and angles were identified.

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Impact of the interface on the fatigue life of steel-based explosively welded heterostructured plates

Derda Szymon, Korolczuk Aleksander, Robak Grzegorz, Prażmowski Mariusz, Paul Henryk, Łagoda Tadeusz, Gupta Munish Kumar

Archives of Civil and Mechanical Engineering

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2023

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Vol. 23, no. 3

art. no. e191, 2023

EN

Melted zones, microcracks, shear bands, and elastic incompatibility of explosively welded materials are features that may initialize cracks at the interface and reduce fatigue strength. This study aims to determine the effect of interfacial defect-like structures on the fatigue strength of explosively welded corrosion-resistant plates. Cyclic axial loading was applied to seven distinct layer-by-layer compositions of Ti Gr 1, Zr 700 alloys, and carbon steels. The interfacial wave height as a metric of potential fatigue life influencing factors along with measured strain amplitude was applied as the input quantities for the Machine Learning based model, i.e. the Gaussian process for regression (GPR). This is a novel and successful application of GPR to estimate the effect of interfacial wave height on the fatigue life of explosively welded plates. For the first time, the effect of the interface feature on fatigue life was estimated quantitatively. The Digital Image Correlation technique was applied to measure the field of cyclic strain for the purpose of verifying if a single strain amplitude is representative of a heterostructured plate. It was found that interfacial wave height is an important feature and its increase by 100 µm reduces the fatigue life of analysed plates by 36%. Additionally, to validate the applicability of explosively welded plates to engineering structures under cyclic loading, the experimental fatigue lives were compared with the design curve of the American Society of Mechanical Engineers (ASME) code.

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Testing of Air-Cooling Efficiency of the Underside of a Turning Tool Carbide Insert in EN-GJL 250 Cast Iron Turning Operations

Bartoszuk Marian, Prażmowski Mariusz, Hurey Igor

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no 4

1--9

EN

This article shows the results of research on the effectiveness of operation of an original tool air cooling system in cutting. A case of turning EN-GJL 250 cast iron with TH10 tungsten carbide cutting inserts without protective coatings was selected for testing. The paper gives constructional details of the tested tool cooling system and discusses the principle of its operation. The research carried out has shown that this way of cooling the cutting insert causes a significant decrease in temperature in all sub-areas of the cutting zone. In addition, air cooling has been proven to significantly reduce cutting tool wear and slightly improve the roughness of the machined surface. The results obtained showed that the proposed method of cooling can be successfully used in the treatment of grey cast iron. In the future, it may serve as a basis for the construction of a professional cooling system for industrial applications.

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Fatigue failure analysis of three-layer Zr–Ti/Zr–Steel composite plates: an insight into the evolution of cracks initiated at the interfaces

Karolczuk Aleksander, Carpinteri Andrea, Robak Grzegorz, Derda Szymon, Prażmowski Mariusz

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 4

604--616

EN

Initiation and evolution of fatigue cracks at the interfaces in three-layer Zr–Ti/Zr–Steel composites is herein examined by in situ optical microscopy for the first time. Specimens cut out from three composite plates comprising Zr 700, Ti Gr. 1, and P265GH steel layers have been subjected to uniaxial fatigue cyclic loading. It is found that mechanical property mismatch between layers and defects at the interfaces can reduce the fatigue life of composite plates. An insight into the evolution of cracks initiated at the interfaces reveals that (1) most of the cracks grow into adjacent layers along two distinct planes, and (2) these cracks could lead to the fatigue failure of composites. One of these planes coincides with the adiabatic shear band orientation found in Ti Gr. 1 and Zr 700 layers. The interfaces in multilayer metallic composite could have excellent fatigue strength depending on their structural properties.