Parallel tubular channel angular pressing (PTCAP) process is a novel recently developed severe plastic deformation technique for fabrication of ultrafine grained (UFG) metallic tubes. This new process consists of two half cycles and is affected by several parameters such as channel angles, deformation ratio and curvature angles. In this paper, the effects of these parameters on the plastic defo...

Abstract The article focuses on the Direct Drive Rotary Friction Welding of ultrafine-grained copper rods, which feature increased mechanical properties and good electrical properties, yet are limited in size. use UFG metals is often by too small dimensions semi-finished elements produced SPD methods. Therefore, production finished machine parts from currently economically unjustified. Dismissa...

Grain refinement can make conventional metals several times stronger, but this comes at dramatic loss of ductility. Here we report a heterogeneous lamella structure in Ti produced by asymmetric rolling and partial recrystallization that can produce an unprecedented property combination: as strong as ultrafine-grained metal and at the same time as ductile as conventional coarse-grained metal. It...

For testing time-dependent material properties by nanoindentation, in particular for long-term creep or relaxation experiments, thermal drift influences on the displacement signal are of prime concern. To address this at room and elevated temperatures, we tested fused quartz at various contact depths at room temperature and ultra-fine grained (ufg) Au at various temperatures. We found that the ...

9 = 0.6 I / s ' 7 = 6.0 0 7 = 2 4 i ti 3 = 6 0 Through close control over green-state powder processing, pure alumina ceramics of 0.5-pm grain size were obtained by sintering at 1250°C. The static grain growth of this material was modest at temperatures below 1300°C. However, dynamic grain growth occurred rapidly during superplastic deformation. Therefore, although the ultrafine-grained alumina...

A dislocation bow-out model has been developed to explain the strength of ultra-fine grained (UFG) materials with grain size roughly between 20 nm to 500 nm. In the model, perfect dislocations are assumed to be nucleated at grain-boundary sources and bow out between two pinning points on a boundary. Yielding is considered to occur when a dislocation takes a semi-circular shape under applied str...

Abstract. Ultrafine-grained S322750 superduplex stainless steel has been obtained through high-pressure torsion (HPT) process. Microstructural evolution after the severe plastic deformation (SPD) shown no phase transformation. Isothermal heat treatment was applied process in order to promote secondary precipitation. Precipitation enhanced ultrafine-grained comparison coarse-grained at same isot...

In this paper, cyclic flaring and sinking (CFS) as a new severe plastic deformation (SPD) method was employed to produce the ultrafine grain (UFG) copper tubes. The extra friction has eliminated in the CFS method that provided the possibility for production of longer UFG tubes compared to the other SPD methods. This process was done periodically to apply more strain and consequently finer grain...

To have an insight into the occurrence of inverse Hall-Petch relationship in ultrafine-grained (UFG) aluminum alloys produced by severe plastic deformation (SPD), ultra-SPD (i.e. inducing several ten thousand shear strains via high-pressure torsion, HPT) followed aging is applied to Al-La-Ce alloy. Average nanograin sizes 40 and 80 nm are successfully achieved together with strain-induced Lomer...