Gradient Structures in Thin‐Walled Metallic Tubes Produced by Continuous High Pressure Tube Shearing Process

Abstract

A new severe plastic deformation process, the authors refer to as High Pressure Tube Shearing (HPTS), is proposed. This type of deformation processing enhances the strength of the walls of metallic tubes by producing gradient microstructures with ultrafine grained layers in near-surface regions. The thickness of the layers associated with a gradient in microstructure can be controlled by tuning the rotational and translational speeds of the process. The paper describes several examples of steel and titanium tubes processed by different variants of HPTS. The possibility of producing gradient microstructures with ultrafine grained layers at inner or outer surface of a tube, or at both surfaces is demonstrated by in-depth theoretical analysis, finite element simulations, and experimental investigation of the microstructure and texture of tube walls.

Green and Affordable Manufacturing Method for Multi-Scale Porous Carbon Nanofibers and Its Application in Vanadium Redox Flow Battery

“…18,19 It is simple and efficient to improve the battery performance by enhancing the physical and chemical properties of the electrode materials. Increasing surface roughness to improve the specific surface area, [20][21][22] introducing hetero-atom functional groups to improve the electrochemical active sites 23,24 and modifying nano-catalyzer to improve the electrocatalytic activity 25,26 of carbon fiber materials are the most commonly used ways to improve the electrochemical performance of carbon fiber materials. Among these strategies, increasing the effective specific surface area of electrode materials is the most cost-effective and easy to achieve mass production.…”

Analytical and numerical approaches to modelling severe plastic deformation

“…A successful exercise in analytical modelling of an axisymmetric forward spiral extrusion process [485] -yet another recent variety of SPD processingemployed an upper bound approach, developed earlier in the context of twist extrusion modelling [486]. Substantial efforts were also put in design and simulation of SPD processing of thin products [487,488], notably thin-walled tubes [315,489,490]. A process dubbed tube channel pressing [491] was studied by Farshidi and Kazeminezhad [492] by employing FEM simulations.…”

“…FEM simulations provide important assistance in evaluating the behaviour of metallic materials during such processes and the mechanical properties of the tubes strengthened by SPD. Particular examples include the so called Cone-Cone method (CCM) [494] in which a cone-shaped tube is deformed by severe twist under high hydrostatic pressure, and the techniques for producing gradient structures in thin-walled cylindrical tubes, such as High Pressure Tube Twisting (HPTT) [315,509] and High Pressure Tube Shearing (HPTS) [489]. An important advantage of the latter technique, which is illustrated schematically in Figure 38, is its continuous character, which makes it amenable to large-scale tube manufacturing.…”

“…This was associated with a microstructure gradient induced by SMAT in a near-surface layer of the material. The benefits of gradient structures were also discussed in a recent work on strengthening thin walled tubes by a process referred to as continuous high pressure tube shearing [489]. Modelling of the mechanical behaviour of such materials calls for new theoretical tools 130 that account for gradient structures.…”

The Role of Mandrel Rotation during CSET Processing Demonstrated on a 3003 Aluminium Alloy

“…In both methods, high hydrostatic pressure is applied on a tube positioned between inner and outer mandrels, each of which may rotate independently thus evoking shear deformation of the tube wall. Similarly, in the high-pressure tube shearing (HPTS) process, a tube has been drawn through a rotating die, and an internal rotating mandrel causes thinning of the tube wall [16]. Rotation and high hydrostatic pressure resulted in local shear deformation which resulted in a fine-grained and frequently gradient microstructure.…”