Accumulative spin-bonding (ASB) as a novel SPD process for fabrication of nanostructured tubes

Nanostructure, Texture Evolution and Mechanical Properties of Aluminum Alloys Processed by Severe Plastic Deformation

“…Total strain at each time is then determined by summation of these increments. The strain rate is calculated by dividing these strain increments to the deformation time of each one (Mohebbi & Akbarzadeh, 2010b). It was demonstrated that the material undergoes a small deformation with high strain rate at any exposure to roller, while at the time between the steps, the strain rate downfalls to zero.…”

“…Circular shaped hollow sections like tubes and cylinders, as a category of engineering components, are also expected to achieve high strengths by nanostructure. Tube spinning is used as a common tube fabricating process (Wong et al, 2003), based on which a coldbonding process titled "spin-bonding" with the advantages of ARB of sheets has been recently proposed (Mohebbi & Akbarzadeh, 2010a, 2010b for manufacturing of high strength thin-walled tubes and cylinders. The SPD process proposed in that work is, in fact, repeatedly spin-bonding of layered tubes (accumulative spin-bonding, ASB) to induce large plastic strain on tubes similar to the ARB of sheets, Fig.…”

“…This is why the stress and strain have such a complicated distribution in this incremental process. There is always an inhomogeneous material flow due to the local deformation between the roller and the preform surface with a high strain rate (Mohebbi & Akbarzadeh, 2010b, 2010c, 2009b.…”

Experimental investigation of three different tube equal channel angular pressing techniques

“…Next, a roller moves axially along the direction of the tube axis. This operation is performed to decrease tube thickness by 50 % [18,19]. The techniques which have been considered are difficult and expensive in the die design set-up and operation and also, high magnitudes of processing variations are seen in these techniques, and hence, it can be said that they are not easily adapted for the fabrication and employment in large scale industrial applications and constructions.…”

Experimental Investigation of the Equal Channel Forward Extrusion Process

“…Based on the geometry of the work-piece, SPD techniques can be divided into the three groups nominating bulk, sheet, and tube classifications. For group 1: equal channel angular pressing (ECAP) [1], high pressure torsion (HPT) [2], twist extrusion (TE) [6], accumulative back extrusion (ABE) [7]; for group 2: equal channel angular rolling (ECAR) [8], accumulative roll bonding (ARB) [9], constrained groove pressing (CGP) [10]; and for group 3: high pressure tube twisting (HPTT) [11], accumulative spin bonding (ASB) [12], tubular channel angular pressing (TCAP) [13] are the major examples. It should be pointed out that the principal rule of all SPD methods consists of imposing shear stress to the sample, increasing the dislocation density in deformed material, formation of dense dislocation walls and then low angle grain boundaries (LAGBs), and, finally, transformation of LAGBs into high angle grain boundaries (HAGBs) [1,[14][15][16][17].…”