Enhanced Shear Deformation in Rod Rolling with Inclined Oval Pass Modification

Analytical model of pass-by-pass strain in rod (or bar) rolling and its applications to prediction of austenite grain size

Rod rolling is a process in which the deformation of the workpiece between the work rolls is quite different from the rod drawing process, but the area strains (natural logarithm of area reduction ratio) multiplied by a constant have been used in the calculation of the pass-by-pass evolution of austenite grain size in rod (or bar) rolling without any verification. Considering that the deformation parameters (strain and strain rate) at a given pass play a crucial role in determining recrystallization behavior, the calculation method for the deformation parameters associated with rod rolling should be examined. In this study, a series of numerical simulations has been carried out using an area strain model [5] and an analytic model [6] which calculate the pass-by-pass strain in the rod rolling process, focusing on the effect of the calculation method for the pass-by-pass strain on the recrystallization behavior and evolution of AGS (austenite grain size) during a given pass. These have been investigated for a six-pass rolling sequence (oval-round or round-oval) designed for this study by incorporating the recrystallization and AGS evolution model being widely used in hot rolling. It was found that the recrystallization behavior and evolution of AGS during a given pass were significantly influenced by the calculation methods for deformation parameters. The area strain model lacks mathematical grounds to be used as input to the equations for recrystallization and AGS evolution.

Atomic-scale deformation mechanism of nano Cu precipitate along the rolling process of ferritic steel

Chapter 7 - Plate lattice metamaterials

The present article reports selected results of a preliminary study of the process of skew rolling of bimetallic rods. The experiments were conducted using a numerically controlled three-roller skew rolling mill. During the tests, bimetallic rods were rolled from billets whose cores and outer sleeves (bushings) were made of different types of steel. The results demonstrate that the proposed method can be successfully used in the production of bimetallic rods. However, proper fastening of the two materials depends on the geometrical parameters of the billets, and the quality of bimetallic rods depends on the heating method used. When the rods are heated without protective atmospheres, the surface layer of the core gets decarburized and the surfaces of the materials being joined together are oxidized, which hinders the welding process and adversely affects the physical and chemical properties of such products. The results of numerical modeling indicate that the material near the surface tends to flow, which may have a negative impact on the welding process. In addition, the distribution of stress in the tool–workpiece contact zone may make welding of the materials difficult. The results reported in this paper are preliminary and constitute a prelude to a more detailed analysis of bimetallic rod rolling.

Instability criterion of materials in combined stress states and its application to orthogonal cutting process

The present article considers the construction of differential equations of equilibrium of geometrically and physically nonlinear ideally elastoplastic in relation to shear deformations of continuous medium under conditions of one-dimensional plane deformation, when the diagrams of volumetric and shear deformation are approximated by biquadratic functions. The construction of physical dependencies is based on calculating the secant moduli of volumetric and shear deformation. When approximating the graphs of the volumetric and shear deformation diagrams using two segments of parabolas, the secant shear modulus in the first segment is a linear function of the intensity of shear deformations; the secant modulus of volumetric expansion-contraction is a linear function of the first invariant of the strain tensor. In the second section of the diagrams of both volumetric and shear deformation, the secant shear modulus is a fractional (rational) function of the shear strain intensity; the secant modulus of volumetric expansion-compression is a fractional (rational) function of the first invariant of the strain tensor. Based on the assumption of independence, generally speaking, from each other of the volumetric and shear deformation diagrams, five main cases of physical dependences are considered, depending on the relative position of the break points of the graphs of the diagrams volumetric and shear deformation. On the basis of received physical equations, differential equations of equilibrium in displacements for continuous medium are derived under conditions of plane one-dimensional deformation. Differential equations of equilibrium in displacements constructed in the present article can be applied in determining stress and strain state of geometrically and physically nonlinear ideally elastoplastic in relation to shear deformations of continuous medium under conditions of plane one-dimensional deformation, closing equations of physical relations for which, based on experimental data, are approximated by biquadratic functions.

Surface texture transfer in skin-pass rolling with the effect of roll surface wear

Simulation of deformation and temperature in multi-pass continuous rolling by three-dimensional FEM

Problems of differential equations construction of equilibrium of a geometrically and physically nonlinear continuous medium under conditions of one-dimensional plane deformation are considered, when the diagrams of volumetric and shear deformation are approximated by quadratic functions. The construction of physical dependencies is based on calculating the secant moduli of volumetric and shear deformation. When approximating the graphs of the volumetric and shear deformation diagrams using two segments of parabolas, the secant shear modulus in the first segment is a linear function of the intensity of shear deformations, the secant modulus of volumetric expansion - contraction is a linear function of the first invariant of the strain tensor. In the second section of the diagrams of both volumetric and shear deformation, the secant shear modulus is a fractional (rational) function of the shear strain intensity, the secant modulus of volumetric expansion - compression is a fractional (rational) function of the first invariant of the strain tensor. Based on the assumption of independence, generally speaking, from each other of the volumetric and shear deformation diagrams, six main cases of physical dependences are considered, depending on the relative position of the break points of the graphs of the diagrams volumetric and shear deformation, each approximated by two parabolas. The differential equations of equilibrium in displacements constructed in the article can be applied in determining the stressed and deformed state of a continuous medium under conditions of one-dimensional plane deformation, the closing equations of physical relations for which, constructed on the basis of experimental data, are approximated by biquadratic functions.

The subject under analysis is construction of differential equations of equilibrium in displacements for plane deformation of physically and geometrically nonlinear continuous media when the closing equations are biquadratically approximated in a Cartesian rectangular coordinate system. Proceeding from the assumption that, generally speaking, the diagrams of volume and shear deformation are independent from each other, six main cases of physical dependences are considered, depending on the relative position of the break points of biquadratic diagrams of volume and shear deformation. Construction of physical dependencies is based on the calculation of the secant module of volume and shear deformation. When approximating the graphs of volume and shear deformation diagrams using two segments of parabolas, the secant shear modulus in the first segment is a linear function of the intensity of shear deformations; the secant modulus of volume expansion-contraction is a linear function of the first invariant of the strain tensor. In the second section of the diagrams of both volume and shear deformation, the secant shear modulus is a fractional (rational) function of the intensity of shear deformations; the secant modulus of volume expansion-contraction is a fractional (rational) function of the first invariant of the strain tensor. The obtained differential equations of equilibrium in displacements can be applied in determining the stress-strain state of physically and geometrically nonlinear continuous media under plane deformation the closing equations of physical relations for which are approximated by biquadratic functions.

Boundary Element Analysis of Cracks in Shear Deformable Plates and Shells. Topics in Engineering, Vol 43

Microstructures, deformation mechanisms and seismic properties of a Palaeoproterozoic shear zone: The Mertz shear zone, East-Antarctica

Deformationprocessing of immiscible systems is observed to disruptthermodynamic equilibrium, often resulting in nonequilibrium microstructures.The microstructural changes including nanostructuring, hierarchicaldistribution of phases, localized solute supersaturation, and oxygeningress result from high-strain extended deformation, causing a significantchange in mechanical properties. Because of the dynamic evolutionof the material under large strain shear load, a detailed understandingof the transformation pathway has not been established. Additionally,the influence of these microstructural changes on mechanical propertiesis also not well characterized. Here, an immiscible Cu-4 at. % Nballoy is subjected to a high-strain shear deformation (∼200);the deformation-induced changes in the morphology, crystal structure,and composition of Cu and Nb phases as a function of total strainare characterized using transmission electron microscopy and atomprobe tomography. Furthermore, a multimodal experiment-guided computationalapproach is used to depict the initiation of deformation by an increasein misorientation boundaries by crystal plasticity-based grain misorientationmodeling (strain ∼0.6). Then, co-deformation and nanolaminationof Cu and Nb are envisaged by a finite element method-based computationalfluid dynamic model with strain ranging from 10 to 200. Finally, theexperimentally observed amorphization of the severely sheared supersaturatedCu–Nb–O phase was validated using the first principle-basedsimulation using density functional theory while highlighting theinfluence of oxygen ingress during deformation. Furthermore, the nanocrystallinemicrostructure shows a >2-fold increase in hardness and compressiveyield strength of the alloy, elucidating the potential of deformationprocessing to obtain high-strength low-alloyed metals. Our approachpresents a step-by-step evolution of a microstructure in an immisciblealloy undergoing severe shear deformation, which is broadly applicableto materials processing based on friction stir, extrusion, rolling,and surface shear deformation under wear and can be directly appliedto understanding material behavior during these processes.

The characteristics of grain boundaries (GBs) and their mechanical responses under external loading are pivotal in governing the strength and plasticity of polycrystalline ceramics. In this study, first-principles calculations were employed to investigate the stability of Σ5 {310}[001] GBs in (HfNbTaTiZr)C high-entropy carbide ceramic (HECCs) and its constituent binary transition-metal carbides (TMCs), as well as their mechanical behavior under shear and tensile deformation. The results showed that the Σ5{310}[001] GBs in all systems were classified into "Open GB" and "Compact GB" based on their morphologies, with the Open GB exhibiting lower GB formation energy and thus greater structural stability. Under shear deformation, all carbides display shear-coupled GB migration, except for the Open GBs in group IVB TMCs, where the formation of C-C bonds induces supercell failure through the rupture of TM-C bonds. Furthermore, the initial migration stress of Open GB in the HECC is higher than that in binary TMCs, highlighting the strengthening effect introduced by multicomponent GBs. Under tensile deformation, binary TMCs containing Compact GB primarily fail through graphitization, whereas the HECC exhibits both graphitization and intergranular fracture. For Open GB, group IVB TMCs yield due to increased excess volume of GB, while group VB TMCs undergo intergranular fracture; both failure mechanisms coexist in the HECC. Notably, the HECC containing Compact GBs exhibits yield strength comparable to the peak strength of binary TMCs, surpassing the "weakest-link" limit typically associated with ideal condition (0 K and defect-free). Overall, this work elucidates the synergistic roles of GB and multicomponent effects in governing mechanical responses in HECC, suggesting that the interplay between multicomponent effects and defects may underlie the exceptional mechanical performance of high-entropy materials. These findings provide theoretical guidance for GB engineering and mechanical optimization in HECCs, and they offer insights into exploring their mechanical behavior under complex defect interactions.