Browsing by Author "Biba, N."

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    Local High Pressure Torsion: A Process for Creating Targeted Heterogeneities in Metallic Materials
    (Springer Nature, 2025) Beygelzimer, E.; Davydenko, O.; Beygelzimer, Y.; Tereshchenko, Y.; Bondarchuk, V.; Shyvaniuk, V.; Fataiev, R.; Shapiro, I.; Balakin, Valerii F.; Biba, N.; Orlov, D.
    ENG: In the light of recent developments in the design of structural materials, micro-architected heterogenous-structure metals are considered among most structurally efficient. In this work, a new technique for Local High Pressure Torsion (L-HPT) enabling the creation of heterogeneous structures through localised deformation processing in sheet metals by impeding a rotating punch is proposed. Using AA5083 aluminium alloy as an example, we show experimentally that the rotation of the punch sets adjacent material layers in motion. This results in more than two-fold increase in material hardness over initial level in the workpiece bulk with rather sharp gradients in hardness level transition. The maximum hardness is observed at the peripheral edge of a punch tip. Finite-element modelling of the L-HPT process confirmed that the rotational flow of workpiece material leads to the accumulation of shear strain. The level of accumulated strain increases with an increase in friction at the contact surface. Further analysis based on dimensionality theory revealed that for such an L-HPT configuration the level of equivalent strain is directly proportional to the ratio of rotation-to-translation speeds at the punch.
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    Use of the Dactyling Effect to Obtain a Compositional Structure in White Iron during Forming
    (IOP Publishing, 2021) Myronova, T.; Ashkelianets, A.; Chukhlib, V.; Biba, N.; Gubskii, S.; Okun, A.
    ENG: Cast iron is traditionally used as a casting alloy for the manufacture of products operating in various industries. White cast irons are used for parts with high wear resistance due to the presence in their composite structure a large number of eutectic carbides, which are located around the dendrites of the solid solution and provide a high level of hardness and strength. The location of eutectic colonies in the form of a mesh causes a low level of ability to withstand impact loading, facilitates the chipping of individual "grains" in abrasive wear and limits the use of these alloys. The use of forming process allows us to grind the eutectic mesh in the structure of white cast iron, which significantly improves the complex of mechanical and operational properties. But the low level of plasticity of white cast iron in the cast state does not allow widespread using white cast iron plastic deformation. The possibility of hot deformation of cast iron workpieces with different speeds and schemes was investigated. The deformation rate of alloys was varied due to the use of different equipment for mass and small-series production using different types of metal forming.