Microstructure and Mechanical Properties of Twist Extruded Pure Aluminum Processed by Post-Rolling

2011 ◽  
Vol 264-265 ◽  
pp. 183-187 ◽  
Author(s):  
S. Ranjbar Bahadori ◽  
Seyed Ali Asghar Akbari Mousavi ◽  
A.R. Shahab
Keyword(s):  
Grain Size ◽  
Pure Aluminum ◽  
Rolling Process ◽  
Extrusion Process ◽  
Ultrafine Grained ◽  
Twist Extrusion ◽  
Aluminum Sample ◽  
Deformation Processes ◽  
Ultrafine Grained Materials ◽  
Extrusion Method

Interest in processing of bulk ultrafine-grained materials has grown significantly over the last years. Severe plastic deformation processes such as twist extrusion have been the essence of these researches and used to decrease the bulk grain size. The bulk gain size can reduce if twist extrusion process combines with a conventional forming technique. In this study, the effects of reduction by employing the rolling process after the twist extrusion method were considered. The twist extrusion process of the commercially pure aluminum sample was carried out using a twisted die with 60º die angle, and the samples were processed through rolling subsequently. As a result of rolling, average microstructure grain size decreased significantly and the hardness amount increased accordingly

Microstructure and Mechanical Properties of the Twist Extruded Pure Copper after Rolling

2012 ◽  
Vol 05 ◽  
pp. 359-366
Author(s):  
Sh. Ranjbar Bahadori ◽  
S. A. A. Akbari Mousavi ◽  
A. R. Shahab
Keyword(s):  
Grain Size ◽  
Metal Forming ◽  
Pure Copper ◽  
Rolling Process ◽  
Extrusion Process ◽  
Mechanical Heterogeneity ◽  
Ultrafine Grained ◽  
Twist Extrusion ◽  
Deformation Processes ◽  
Ultrafine Grained Materials

Recently, severe plastic deformation processes have been the essence of metal forming researches to produce ultrafine-grained materials. Twist Extrusion is one of the most unprecedented methods developed in recent years, but has some deficiencies. The main one is the microstructure and mechanical heterogeneity, occurring after twist extrusion. Performing rolling as a conventional forming technique was suggested as a solution in this paper. It not only decreased the grain size, but also reduced the mechanical heterogeneity, and improved the grain size distribution. Employing the twist extrusion process on pure copper samples was carried out using a twisted die with 60° die angle, and the samples were processed through rolling subsequently. The results demonstrated that employing the rolling process enhanced grain size homogeneity and bulk strength.

Prediction of the Stress-Strain Response of the Ultrafine-Grained Materials Using Multi-Scale Analysis

2010 ◽  
Author(s):  
Mihaela Banu ◽  
Mitica Afteni ◽  
Alexandru Epureanu ◽  
Valentin Tabacaru
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Aluminum Alloy ◽  
Severe Plastic Deformation ◽  
Scale Analysis ◽  
Multi Scale ◽  
Ultrafine Grained ◽  
Deformation Processes ◽  
Ultrafine Grained Materials ◽  
Multi Scale Analysis

There are several severe plastic deformation processes that transform the material from microsized grains to the nanosized grains under large deformations. The grain size of a macrostructure is generally 300 μm. Following severe plastic deformation it can be reached a grain size of 200 nm and even less up to 50 nm. These structures are called ultrafine grained materials with nanostructured organization of the grains. There are severe plastic deformation processes like equal angular channel, high pressure torsion which lead to a 200 nm grain size, respectively 100 nm grain size. Basically, these processes have a common point namely to act on the original sized material so that an extreme deformation to be produced. The severe plastic deformation processes developed until now are empirically-based and the modeling of them requires more understanding of how the materials deform. The macrostructural material models do not fit the behavior of the nanostructured materials exhibiting simultaneously high strength and ductility. The existent material laws need developments which consider multi-scale analysis. In this context, the present paper presents a laboratory method to obtain ultrafine grains of an aluminum alloy (Al-Mg) that allows the microstructure observations and furthermore the identification of the stress–strain response under loadings. The work is divided into (i) processing of the ultrafine-grained aluminum alloy using a laboratory-scale process named in-plane controlled multidirectional shearing process, (ii) crystallographic analysis of the obtained material structure, (iii) tensile testing of the ultrafine-grained aluminum specimens for obtaining the true stress-strain behavior. Thus, the microscale phenomena are explained with respect to the external loads applied to the aluminum alloy. The proposed multi-scale analysis gives an accurate prediction of the mechanical behavior of the ultrafine-grained materials that can be further applied to finite element modeling of the microforming processes.

The Processing of Ultrafine-Grained Materials Using High-Pressure Torsion

2007 ◽  
Vol 558-559 ◽  
pp. 1283-1294 ◽  
Author(s):  
Cheng Xu ◽  
Z. Horita ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
High Pressure ◽  
High Pressure Torsion ◽  
Metallic Materials ◽  
Grain Sizes ◽  
Ultrafine Grained ◽  
Wide Range ◽  
Ultrafine Grained Materials ◽  
Thin Disks

It is now well-established that processing through the application of severe plastic deformation (SPD) leads to a significant reduction in the grain size of a wide range of metallic materials. This paper examines the fabrication of ultrafine-grained materials using high-pressure torsion (HPT) where this process is attractive because it leads to exceptional grain refinement with grain sizes that often lie in the nanometer or submicrometer ranges. Two aspects of HPT are examined. First, processing by HPT is usually confined to samples in the form of very thin disks but recent experiments demonstrate the potential for extending HPT also to bulk samples. Second, since the strains imposed in HPT vary with the distance from the center of the disk, it is important to examine the development of inhomogeneities in disk samples processed by HPT.

Microstructure-Property Relationships in Sintered Alumina Ceramics

2006 ◽  
Vol 45 ◽  
pp. 564-571
Author(s):  
Dušan Galusek
Keyword(s):  
Grain Size ◽  
Stress State ◽  
Liquid Phase ◽  
Processing Conditions ◽  
Microstructure Development ◽  
Alumina Ceramics ◽  
Polycrystalline Alumina ◽  
Glass Forming ◽  
Ultrafine Grained ◽  
Ultrafine Grained Materials

The paper gives a brief overview of polycrystalline alumina ceramics, including the solid-state sintered and ultrafine grained materials, and the liquid phase sintered aluminas. The influence of glass-forming sintering additives of commercial interest (MgO, CaO, SiO2) and processing conditions on microstructure development of polycrystalline alumina ceramics are discussed in more detail. The influence of grain size, the presence and composition of grain boundary glass, and of secondary crystalline phases in partially crystallized triple pockets on stress state in alumina is discussed.

Developing Superplasticity in Metallic Alloys through the Application of Severe Plastic Deformation

2008 ◽  
Vol 604-605 ◽  
pp. 97-111 ◽  
Author(s):  
Roberto B. Figueiredo ◽  
Megumi Kawasaki ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
Grain Size ◽  
Severe Plastic Deformation ◽  
Grain Refinement ◽  
Elevated Temperatures ◽  
Metallic Alloys ◽  
Superplastic Flow ◽  
Ultrafine Grained ◽  
Ultrafine Grained Materials

Processing through the application of severe plastic deformation (SPD) provides an opportunity for achieving very significant grain refinement in bulk metals. Since the occurrence of superplastic flow generally requires a grain size smaller than ~10 µm, it is reasonable to anticipate that materials processed by SPD will exhibit superplastic ductilities when pulled in tension at elevated temperatures. This paper summarizes the fundamental principles of SPD processing and describes recent results demonstrating the occurrence of exceptional superplastic flow in these ultrafine-grained materials.

Fabrication of ultrafine grained materials by Nonlinear Twist Extrusion (NTE)

2017 ◽  
Vol 2017.92 (0) ◽  
pp. M505
Author(s):  
Naoki KOMADA ◽  
Hiroyuki MIYAMOTO ◽  
Motohiro YUASA ◽  
Chika MORISHIMA
Keyword(s):  
Ultrafine Grained ◽  
Twist Extrusion ◽  
Ultrafine Grained Materials

Effect of Copper Addition to Aluminum on its Metallurgical, Mechanical Characteristics and Surface Roughness after Rolling

2016 ◽  
Vol 689 ◽  
pp. 12-16
Author(s):  
Adnan I.O. Zaid ◽  
Safwan M.A. Al-Qawabah
Keyword(s):  
Surface Roughness ◽  
Grain Size ◽  
Surface Quality ◽  
Pure Aluminum ◽  
Weight Ratio ◽  
Rolling Process ◽  
Copper Addition ◽  
Commercially Pure ◽  
Effect Of Copper ◽  
Cast Condition

Aluminum and its alloys are widely used materials in industrial and engineering applications. They are second in use after steel due to their attractive properties e.g. strength-to-weight ratio, their electrical and thermal conductivities, and corrosion resistance. However, against these attractive properties commercially pure aluminum has certain limitations in the cast condition because it solidifies in large grain size columnar structure which reduces its mechanical strength and surface quality. It is, therefore, always alloyed with other elements to reduce or eliminate these defects. In this paper, the effect of copper addition at a rate of 4% Wt. to commercially pure aluminum both in the cast and after rolling conditions is investigated. Aluminum sheets and aluminum-4% copper sheets were cold rolled in three successive passes, from 4 mm to 3mm to 1.3 mm. After each pass, the grain size, Vickers micro-hardness and surface roughness were determined and discussed. It was found that addition of 4% Cu to commercially pure Al in the cast condition resulted in refining its microstructure both in the cast and after rolling conditions. Furthermore, the rolling process resulted in enhancement of the surface quality only after the first and second passes.

Measures of Ductility for UFG Materials Obtained by SPD

2009 ◽  
Vol 633-634 ◽  
pp. 223-230 ◽  
Author(s):  
Yan Beygelzimer ◽  
O. Prokof'eva ◽  
R. Kulagin ◽  
Viktor Varyukhin ◽  
Sergey Synkov
Keyword(s):  
Plastic Deformation ◽  
Coarse Grained ◽  
Alloy Structure ◽  
Commercial Grade ◽  
Ultrafine Grained ◽  
Twist Extrusion ◽  
Coarse Grained State ◽  
Ultrafine Grained Materials ◽  
Reduction Of Area ◽  
Discontinuity Flaws

It is shown that for ultrafine grained materials obtained with severe plastic deformation methods, the value of elongation up to fracture does not determine ductility, while the reduction of area up to fracture does determine it. The latter characteristic gives information about how an alloy structure resists the formation of discontinuity flaws under deformation in a hard stress state. We show that for a commercial grade titanium that underwent Twist Extrusion (TE), the value of , and thus ductility, is higher in the UFG state than in the coarse-grained state.

Crack Blunting through Lattice Dislocation Slip in Nanocrystalline and Ultrafine-Grained Materials

2009 ◽  
Vol 633-634 ◽  
pp. 55-62
Author(s):  
Ilya A. Ovidko ◽  
A.G. Sheinerman
Keyword(s):  
Grain Size ◽  
Size Effect ◽  
Stress Fields ◽  
Dislocation Slip ◽  
Cubic Phase ◽  
Grain Size Effect ◽  
Dislocation Emission ◽  
Ultrafine Grained ◽  
Ultrafine Grained Materials ◽  
Crack Blunting

The grain size effect on blunting of cracks in nanocrystalline and ultrafine-grained materials (UFG) is theoretically described. Within our description, lattice dislocations emitted from cracks are stopped at grain boundaries. The stress fields of these dislocations suppress further dislocation emission from cracks in nanocrystalline and UFG materials, and the suppression depends on grain size. The dependences of the number of dislocations emitted by a crack on grain size (ranging from 10 to 300 nm) in Cu and 3C-SiC (the cubic phase of silicon carbide) are calculated which characterize the grain size effect on crack blunting that crucially influences ductility of these materials.

Sign in / Sign up

Export Citation Format

Share Document