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Refinement of microstructure and mechanical properties of titanium processed by twist extrusion and subsequent rolling

Microstructure and mechanical properties as well as thermal stability of commercially pure titanium VT1-0 subjected to severe plastic deformation by twist extrusion (TE) were studied before and after low-temperature annealing and cold rolling. TE leads to a refinement of structural fragments to sizes of less than 1 μm, enhancement of strength, and the appearance of strong anisotropy of mechanical

Destabilization of fcc stable materials during SPD under high pressure

It was shown that of a fine α-phase was formed in the Hadfield steel after a cold plastic deformation to E = 50%. Nuclei of the ex-phase of deformed samples reduced the decomposition start temperature of the austenite by 180°C. Fine crystals of an α-phase nearly 30 nm in size, whose concentration was as high as ∼2.3%, were detected in a steel Fe 79.55Mn17Al3Co0.45 after a SPD to ε = 92%. A steel F

Microstructure, mechanical properties and anysotropy of pure ti processed by twist extrusion and cold rolling

It is investigated UFG structure formation in CP Ti bulks processed by SPD (cold Twist Extrusion (TE), true strain e∼5.1, with the following Cold Rolling (CR), true strain e∼0.7). Evolution of microstructure and tensile mechanical properties in the CP Ti were investigated under room temperature. After the TE, in transversal section it is formed structure fragments with size less 1 μm. Strength inc

Screw extrusion

The information on a new method of severe plastic deformation viz. screw extrusion (SE) is presented. Various SE schemes are considered. Experience of realization of this process is described. Effect of SE on mechanical characteristics of technically pure titanium (VT1-0) is analyzed.

Metal plasticity during the twist extrusion

The new way for deriving severe plastic deformations (SPD) by the twist extrusion (TE) is offered and the new kinematically possible field of defrormation rates is proposed. The value of the accumulated deformation after one pass is calculated. The upper estimate for the quantity of toughness resource exhaust is carried out. That allows to estimate the maximum number of passes without specimen fai

Features of twist extrusion : Method, structures & material properties

During the last decade it has been shown that severe plastic deformation (SPD) is a very effective for obtaining ultra-fine grained (UFG) and nanostructured materials. The basic SPD methods are High Pressure Torsion (HPT) and Equal Channel Angular Extrusion (ECAE). Recently several new methods have been developed: 3D deformation, Accumulative Roll Bonding, Constrained Groove Pressing, Repetitive C

Social/economic costs and health-related quality of life in patients with cystic fibrosis in Europe

Objectives: Our goal was to provide data on the economic burden and health-related quality of life (HRQOL) of patients with cystic fibrosis (CF) and their caregivers in Europe. Methods: A cross-sectional study was carried out on adults and children with CF in eight European countries. Patients completed an anonymous questionnaire regarding their socio-demographic characteristics, use of healthcare

Microstructural evolution of titanium under twist extrusion

We present some experimental results describing microstructural evolution in commercially pure titanium during severe plastic deformation by twist extrusion (TE). In particular, we show that increasing the number of TE passes leads to the decrease of the grain size d in both orthogonal and parallel cross-sections of the work piece. For example, if in its original state titanium has d ∼ 25 μm, then

A new severe plastic deformation method : Twist extrusion

One of the most effective methods for obtaining bulk ultrafine-grained materials is severe plastic deformation that is typically done using equal channel angular pressing. In this work we describe and analyze a new method for obtaining severe plastic deformations proposed by the first author. The method is based on direct extrusion and was called "twist extrusion" The main idea of the method is to

Useful properties of twist extrusion

We present an experimental study of the kinematics of twist extrusion (TE) and show that TE has the following properties: (i) as in equal-channel angular pressing (ECAP), the mode of deformation in twist extrusion is simple shear. Unlike in ECAP, there are two shear planes; one of them is perpendicular and the other is parallel to the specimen axis. (ii) The following processes are present during

Finance and economic growth : The case of Sweden 1834-1991

This study examines the long-run relationship between finance and economic growth in Sweden from the 1830s until the 1990s using recently developed econometric techniques for tests of cointegration. The role of investment, education and technological progress (patents) is accounted for as well in order to assess the relative importance of the development of the financial system for growth performaThis study examines the long-run relationship between finance and economic growth in Sweden from the 1830s to the 1990s using recently developed econometric techniques for tests of cointegration. The role of investment, education and technological progress (patents) is accounted for as well in order to assess the relative importance of the development of the financial system for growth performance

Improvement of mechanical properties in SUS304L steel through the control of bimodal microstructure characteristics

The present work deals with achieving improvement in the mechanical properties of SUS304L stainless steel through the application of a unique microstructure design termed as 'Harmonic structure', and establishing a co-relationship between various microstructural characteristics and mechanical properties. Harmonic structure essentially means a bimodal grain size distribution with a specific periodi

Asymmetric accumulative roll bonding of aluminium-titanium composite sheets

Aluminium-titanium (Al/Ti) composite sheets were fabricated via asymmetric accumulative roll bonding (AARB), which capitalises on additional shear to enhance plastic deformation. Multi-layers of Al alloy (AA1050) and commercially-pure Ti sheets were alternatively stacked and rolled-bonded with varied roll diameter ratios (dr) ranging from 1 to 2, for up to four passes. Annealing of selected compos

The control of texture to improve high-cyclic fatigue performance in copper after equal channel angular pressing

High-cyclic fatigue life in ultra-fine grained materials fabricated by equal channel angular pressing (ECAP) suffers from a specific shear texture induced during the fabrication as has been demonstrated in the present study on the example of pure copper. This texture promotes orientation of the easy glide crystallographic planes to be aligned parallel to the shear plane in ECAP. If specimens for t

Role of strain reversal in grain refinement by severe plastic deformation

Most of severe plastic deformation processes involve strain reversal. Till now quite big number of researches has been done on indirect study of its role, which discusses the effect of loading path in ultra-fine grained structure formation. This work is aimed to study directly the role of the strain reversal in grain refinement by severe plastic deformation. A 99.99% purity aluminum was processed

Plastic flow, structure and mechanical properties in pure Al deformed by twist extrusion

Twist extrusion (TE) is known as one of newly developed, but still moderately studied severe plastic deformation methods. This research was initiated to conduct a detailed study of structure-properties relationship evolution during TE processing. The evolution of macrostructure, Vickers hardness and tensile properties was studied in 99.99% purity aluminum during twist extrusion processing at room