Effect of Equal-Channel Angular Pressing on the Creep Resistance of Precipitation-Strengthened Alloys

2010 ◽  
Vol 667-669 ◽  
pp. 897-902 ◽  
Author(s):  
Vàclav Sklenička ◽  
Petr Král ◽  
Jiří Dvořák ◽  
Marie Kvapilová ◽  
Megumi Kawasaki ◽  
...  
Keyword(s):  
Equal Channel Angular Pressing ◽  
Creep Resistance ◽  
Creep Behaviour ◽  
Intensive Research ◽  
Angular Pressing ◽  
Factors Influencing ◽  
Zr Alloys

Despite intensive research efforts in precipitation-strengthened alloys processed by equal-channel angular pressing (ECAP), so far only a few investigations have been conducted on their creep behaviour and the results from these studies are controversial. This paper examines these differences and evaluates some factors influencing the creep resistance of the binary Al-0.2%Sc and Cu-0.2% Zr alloys processed by ECAP.

Effect of Equal-Channel Angular Pressing (ECAP) on Creep in Aluminium Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 2904-2909 ◽  
Author(s):  
Vàclav Sklenička ◽  
Jiří Dvořák ◽  
Marie Kvapilová ◽  
Milan Svoboda ◽  
Petr Král ◽  
...  
Keyword(s):  
Equal Channel Angular Pressing ◽  
Aluminium Alloys ◽  
Creep Resistance ◽  
Room Temperature ◽  
Creep Behaviour ◽  
Coarse Grained ◽  
Pure Aluminium ◽  
Creep Tests ◽  
Angular Pressing ◽  
Compression Creep

This paper examines the effect of equal-channel angular pressing (ECAP) on creep behaviour of pure aluminium, binary Al-0.2wt.%Sc alloy and ternary Al-3wt.%Mg-0.2wt.%Sc alloy. The ECAP was conducted at room temperature with a die that had a 90° angle between the channels and 8 repetitive ECAP passes followed route BC. Constant stress compression creep tests were performed at 473 K and stresses ranging between 16 to 80 MPa on ECAP materials and, for comparison purposes, on the initial coarse-grained materials. The results showed that the creep resistance of the ECAP processed Al-Sc and Al-Mg-Sc alloys was markedly deteriorated with respect to unpressed coarse-grained materials.

Factors Influencing Ductility in Ultrafine-Grained Metals Processed by Equal-Channel Angular Pressing

2009 ◽  
Vol 633-634 ◽  
pp. 341-352 ◽  
Author(s):  
Roberto B. Figueiredo ◽  
Zhi Chao Duan ◽  
Megumi Kawasaki ◽  
Terence G. Langdon
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Equal Channel Angular Pressing ◽  
Elevated Temperatures ◽  
Testing Temperature ◽  
Ambient Temperatures ◽  
Angular Pressing ◽  
Factors Influencing ◽  
Ultrafine Grained ◽  
Processed Material

The processing of bulk metals through the application of severe plastic deformation provides an opportunity for achieving exceptional grain refinement to the submicrometer or even the nanometer range. This paper examines the characteristics of metals processed by equal-channel angular pressing with special emphasis on the levels of ductility that may be attained. It is shown that the amount of ductility is dependent not only upon the composition of the material but also, and to a major extent, upon the testing temperature. Specifically, the ductilities are often low at ambient temperatures where the strength of the as-processed material is relatively high but, by contrast, exceptionally high superplastic ductilities may be achieved over short ranges of strain rate when testing at elevated temperatures.

Inhomogeneity of Microstructure and Creep of ECAP Aluminium

2006 ◽  
Vol 503-504 ◽  
pp. 245-250 ◽  
Author(s):  
Vàclav Sklenička ◽  
Petr Král ◽  
L. Ilucová ◽  
Ivan Saxl ◽  
Jiří Dvořák ◽  
...  
Keyword(s):  
Equal Channel Angular Pressing ◽  
High Purity ◽  
Creep Behaviour ◽  
Pure Aluminium ◽  
Mesoscopic Scale ◽  
Angular Pressing

High purity (99.99%) pure aluminium processed by equal channel angular pressing (ECAP) was examined in terms of the ECAP microstructure inhomogeneity and its creep behaviour. The results indicate that an inhomogeneity of the ECAP microstructure in mesoscopic scale may influence the creep behaviour of the pressed material.

Factors influencing the equal-channel angular pressing of Ti–6Al–4V alloy having lamellar microstructure

2008 ◽  
Vol 493 (1-2) ◽  
pp. 164-169 ◽  
Author(s):  
Young Gun Ko ◽  
Duck Young Hwang ◽  
Dong Hyuk Shin ◽  
Sunghak Lee ◽  
Chong Soo Lee
Keyword(s):  
Equal Channel Angular Pressing ◽  
Lamellar Microstructure ◽  
Angular Pressing ◽  
Factors Influencing

scholarly journals Effect of Chemical Composition on Structure and Properties of Ultrafine Grained Cu-Cr-Zr Alloys Produced by Equal-Channel Angular Pressing

2004 ◽  
Vol 45 (7) ◽  
pp. 2187-2191 ◽  
Author(s):  
Alexei Vinogradov ◽  
Yasushi Suzuki ◽  
Takahiko Ishida ◽  
Kazuo Kitagawa ◽  
Vladimir I. Kopylov
Keyword(s):  
Chemical Composition ◽  
Equal Channel Angular Pressing ◽  
Structure And Properties ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Zr Alloys

Microstructure Stability and Creep Behaviour of a Cu-0.2wt.%Zr Alloy Processed by Equal-Channel Angular Pressing

2010 ◽  
Vol 667-669 ◽  
pp. 821-826 ◽  
Author(s):  
Jiří Dvořák ◽  
Petr Král ◽  
Marie Kvapilová ◽  
Milan Svoboda ◽  
Vàclav Sklenička
Keyword(s):  
Electron Microscopy ◽  
Equal Channel Angular Pressing ◽  
Creep Behaviour ◽  
Tensile Creep ◽  
Creep Tests ◽  
Creep Properties ◽  
Angular Pressing ◽  
Microstructure Stability ◽  
Transmission Electron ◽  
Zr Alloy

A dispersion-strengthened Cu-0.2 wt.% Zr alloy was subjected to equal-channel angular pressing (ECAP) at room temperature for up to 12 passes through route BC using a die having a channel angle of 90°. The microstructural investigations were performed using both transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Tensile creep tests were conducted at temperature 673 K and at the applied stress in the range from 80 to 180 MPa. The migration of boundaries and subsequent grain growth were restricted by Cu9Zr2 precipitates. The study was performed in order to evaluate the effects of severe plastic deformation and precipitation on creep behaviour and microstructure of the pressed alloy. It was found that creep behaviour is strongly dependent on number of ECAP passes. The pressed alloy after up to 4 ECAP passes exhibited a considerable improvement in creep properties in comparison with the unpressed alloy.

Microstructural Evolution and Creep of an Al-0.2wt.%Sc Alloy after Equal-Channel Angular Pressing

2008 ◽  
Vol 584-586 ◽  
pp. 846-851 ◽  
Author(s):  
Petr Král ◽  
Jiří Dvořák ◽  
Vàclav Sklenička
Keyword(s):  
Electron Microscopy ◽  
Applied Stress ◽  
Creep Resistance ◽  
Creep Behaviour ◽  
Shear Bands ◽  
Synergetic Effect ◽  
Grain Boundary Sliding ◽  
Creep Testing ◽  
Creep Tests ◽  
Angular Pressing

Experiments were conducted on an Al-0.2wt.%Sc alloy to evaluate the effect of equalchannel angular pressing (ECAP) on its creep behaviour. ECAP was conducted at room temperature with a die that had an internal angle of 90° between the two parts of the channel. The subsequent extrusion passes were performed by route BC up to 8 ECAP passes. Creep tests in tension were performed on the as-pressed samples at 473 K under an applied stress range between 10 to 50 MPa. For comparison purposes, some creep tests were performed also on the unpressed alloy. Following ECAP and creep testing, samples were prepared for examination by means of transmission electron microscopy (TEM) and scanning electron microscopy (SEM) equipped with an electron back scattering diffraction (EBSD) unit. The observation of the surface of the ECAPed samples after creep exposure showed the occurrence of mesoscopic shear bands. The EBSD data reveal that these bands are separated by high angle grain boundaries. The creep resistance of an alloy is a little decreased after one ECAP pass. However, successive ECAP pressing lead to a noticeable decrease of the creep properties. Thus, the Al-0.2wt.%Sc alloy processed by 8 ECAP passes exhibited faster creep rate by about two and/or three orders of magnitude than the unpressed alloy when creep testing at 473 K and at the same applied stress. The detrimental effect of ECAP on the creep resistance is probably a consequence of a synergetic effect of mesoscopic sliding of groups of grains along shear bands, more intensive grain boundary sliding and creep cavitation in creep of the ultrafine-grained material.

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