Mechanical Properties and Microstructure Development of Ultrafine-Grained Cu Processed by ECAP

2008 ◽  
Vol 584-586 ◽  
pp. 440-445 ◽  
Author(s):  
Miloš Janeček ◽  
Jakub Čížek ◽  
Milan Dopita ◽  
Robert Král ◽  
Ondřej Srba
Keyword(s):  
Room Temperature ◽  
Defect Density ◽  
Mechanical Tests ◽  
Microstructure Development ◽  
Vacancy Clusters ◽  
Ecap Pass ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Positron Annihilation Spectrometry ◽  
The Mean

Technical purity Cu (99.95 wt%) polycrystals have been processed at room temperature by equal channel angular pressing. The results of mechanical tests and the microstructure characterization by various experimental techniques are presented. The yield stress as well as the strength were shown to increase with increasing strain and exceed the respective values of a coarsegrained material. The microstructure development and its fragmentation after ECAP was investigated by the TEM and EBSD. The proportion of high angle grain boundaries was found to increase with increasing strain reaching the value of 90% after 8 ECAP passes. Two kinds of defects were identified in ECAP specimens by positron annihilation spectrometry (PAS): (a) dislocations which represent the dominant kind of defects, and (b) small vacancy clusters (so called microvoids). The main increase of defect density was found to occur during the first ECAP pass. PAS analysis indicated that in the specimens subjected to one ECAP pass the mean dislocation density ρD and the concentration of microvoids cν exceeded the values of 1014 m-2 and 10-4 at.-1, respectively. After 4 passes, the number of defects becomes saturated and practically does not change with increasing strain.

Local Investigations of the Mechanical Properties of Ultrafine Grained Metals by Nanoindentations

2006 ◽  
Vol 503-504 ◽  
pp. 31-36 ◽  
Author(s):  
Johannes Mueller ◽  
Karsten Durst ◽  
Dorothea Amberger ◽  
Matthias Göken
Keyword(s):  
Mechanical Properties ◽  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Strain Rates ◽  
Fcc Metals ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Indentation Strain

The mechanical properties of ultrafine-grained metals processed by equal channel angular pressing is investigated by nanoindentations in comparison with measurements on nanocrystalline nickel with a grain size between 20 and 400 nm produced by pulsed electrodeposition. Besides hardness and Young’s modulus measurements, the nanoindentation method allows also controlled experiments on the strain rate sensitivity, which are discussed in detail in this paper. Nanoindentation measurements can be performed at indentation strain rates between 10-3 s-1 and 0.1 s-1. Nanocrystalline and ultrafine-grained fcc metals as Al and Ni show a significant strain rate sensitivity at room temperature in comparison with conventional grain sized materials. In ultrafine-grained bcc Fe the strain rate sensitivity does not change significantly after severe plastic deformation. Inelastic effects are found during repeated unloading-loading experiments in nanoindentations.

Structure Evolution and Deformation Mechanisms in Ultrafine-Grained Aluminum under Tension at Room Temperature

2010 ◽  
Vol 667-669 ◽  
pp. 915-920
Author(s):  
Konstantin Ivanov ◽  
Evgeny V. Naydenkin
Keyword(s):  
Grain Boundary ◽  
Room Temperature ◽  
Grain Boundary Sliding ◽  
Deformation Mechanisms ◽  
Structure Evolution ◽  
Dislocation Slip ◽  
Polished Surface ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Boundary Sliding

Deformation mechanisms occurring by tension of ultrafine-grained aluminum processed by equal-channel angular pressing at room temperature are investigated using comparative study of the microstructure before and after tensile testing as well as deformation relief on the pre-polished surface of the sample tested. Deformation behavior and structure evolution during tension suggest development of grain boundary sliding in addition to intragrain dislocation slip. Contribution grain boundary sliding to the overall deformation calculated using the magnitude of shift of grains relative to each other is found to be ~40%.

Unique Features of Ultrafine-Grained Microstructures in Materials Having Low Stacking Fault Energy

2010 ◽  
Vol 659 ◽  
pp. 171-176 ◽  
Author(s):  
Jenő Gubicza ◽  
Nguyen Q. Chinh ◽  
János L. Lábár ◽  
Zoltán Hegedűs ◽  
Terence G. Langdon
Keyword(s):  
Equal Channel Angular Pressing ◽  
Room Temperature ◽  
Strong Dependence ◽  
Stacking Fault ◽  
Stacking Fault Energy ◽  
Controlled Processes ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Number Of Passes

The evolution of the microstructure during processing by equal-channel angular pressing (ECAP) in silver having extremely low stacking fault energy was studied up to 16 passes. It was shown that at high strains the contribution of twinning to deformation increased at the expense of dislocation-controlled processes. It was also found that during storage at room temperature (i.e. at the temperature of ECAP) there was a self-annealing of the severely deformed microstructure after 1 month and its degree was revealed to have a strong dependence on the number of passes.

The Effect of Ultrafine-Grained Structure of Al-30Zn on the Shape Forming Ability at Sheet Metal Forming

2018 ◽  
Vol 385 ◽  
pp. 228-233
Author(s):  
Elena V. Bobruk ◽  
Denis G. Tyulenev ◽  
Oleg V. Golubev ◽  
Maxim Y. Murashkin
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Room Temperature ◽  
High Pressure Torsion ◽  
Aluminum Matrix ◽  
Test Method ◽  
Coarse Grained ◽  
Angular Pressing ◽  
Ultrafine Grained

High pressure torsion (HPT) and equal channel angular pressing in parallel channels (ECAP-PC) at room temperature are used to form homogeneous ultrafine-grained (UFG) structure with a grain size of the aluminum matrix of 350 and 700 nm, respectively, in Al-30Zn (wt. %) specimens. The UFG samples with special geometry produced from the specimens processed by SPD techniques were subjected to sphere-shaped dimple extrusion testing (via the Erikson test method) and bended plate extrusion to determine the material formability during cold sheet metal forming. The same tests were performed on the material with coarse-grained (CG) structure for the sake of comparison. The obtained results are discussed.

Mechanical Properties of an Al-Mg-Sc Alloy Subjected to Intense Plastic Straining

2010 ◽  
Vol 638-642 ◽  
pp. 1952-1958 ◽  
Author(s):  
Rustam Kaibyshev ◽  
Elena Avtokratova ◽  
O.S. Sitdikov
Keyword(s):  
Mechanical Properties ◽  
Cold Rolling ◽  
Yield Stress ◽  
Room Temperature ◽  
Total Elongation ◽  
Warm Rolling ◽  
Ultimate Stress ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
High Reduction

Effect of intense plastic straining on rollability and service properties of an Al-6%Mg-0.3%Sc alloy was examined. Ultrafine-grained structure (UFG) was produced by equal-channel angular pressing (ECAP) to a strain of 8 at a temperature of 325oC. The formation of UFG structure resulted in increase in the yield stress from 223 MPa to 285 MPa and ultimate stress from 350 MPa to 389 MPa in comparison with initial hot extruded condition. Total elongation slightly decreased from 33% to 29%. After ECAP, the material was subjected to cold and isothermal warm rolling. The formation of UFG structure resulted in enhanced rollability of the present alloy at room temperature. Cold rolling with high reduction provides the development of heavily deformed microstructure with high dislocation density, while the isothermal warm rolling does not remarkably affect the microstructure produced by ECAP. The mechanical properties after ECAP and ECAP with subsequent isothermal rolling were roughly similar. In contrast, cold rolling to the same strain resulted in significant increase of yield stress (495 MPa) and ultimate stress (536 MPa). Total elongation attained was 13%.

Ultrafine Grained Dual Phase Steels Fabricated by Equal Channel Angular Pressing

2006 ◽  
Vol 503-504 ◽  
pp. 447-454 ◽  
Author(s):  
Dong Hyuk Shin ◽  
Woo Gyeom Kim ◽  
Jung Yong Ahn ◽  
Kyung Tae Park ◽  
Yong Suk Kim
Keyword(s):  
Strain Hardening ◽  
Equal Channel Angular Pressing ◽  
Room Temperature ◽  
Intercritical Annealing ◽  
Total Elongation ◽  
Coarse Grained ◽  
Dual Phase ◽  
Dual Phase Steels ◽  
Angular Pressing ◽  
Ultrafine Grained

Ultrafine grained (UFG) ferrite-martensite dual phase steels were fabricated by equal channel angular pressing and subsequent intercritical annealing. Their room temperature tensile properties were examined and compared to those of coarse grained counterpart. The formation of UFG martensite islands of ~ 1 μm was not confined to the former pearlite colonies but they were uniformly distributed throughout UFG matrix. The strength of UFG dual phase steels was much higher than that of coarse grained counterpart but uniform and total elongation were not degraded. More importantly, unlike most UFG metals showing negligible strain hardening, the present UFG dual phase steels exhibited extensive rapid strain hardening.

The Influence of Processing Conditions on Hardness Homogeneity Evolution in Commercially Pure Cast Aluminium Processed by ECAP

2010 ◽  
Vol 654-656 ◽  
pp. 1211-1214 ◽  
Author(s):  
Sri Lathabai ◽  
Margarita Vargas ◽  
Matthieu Larroque ◽  
Claude Urbani
Keyword(s):  
Room Temperature ◽  
Distribution Maps ◽  
Microhardness Distribution ◽  
Cast Aluminium ◽  
Angular Pressing ◽  
Average Hardness ◽  
Commercially Pure ◽  
First Pass ◽  
Hardness Increase ◽  
The Mean

Commercially pure cast aluminium was subjected to equal channel angular pressing (ECAP) at room temperature using routes A, Bc and C. Microhardness distribution maps were produced on sections of extruded billets after one, two, three and four passes for each of the processing routes. It was found that the mean hardness increased significantly already after the first pass. With subsequent passes, the hardness increase was smaller but the hardness distribution became narrower, indicating increasing homogeneity. For route Bc, a slight decrease in average hardness was observed after the fourth pass. The mean hardness after four passes was highest for the route C sample, followed by the route A and route Bc samples.

Mechanical Properties of Ultrafine-Grained Al Alloy for Engineering Machinery

2012 ◽  
Vol 629 ◽  
pp. 198-202 ◽  
Author(s):  
Ping Yang ◽  
Kai Huai Yang
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Equal Channel Angular Pressing ◽  
Room Temperature ◽  
Al Alloy ◽  
Fracture Modes ◽  
Annealed State ◽  
Angular Pressing ◽  
Ultrafine Grained

Three groups of commercial 1050 Al alloy were subjected to equal channel angular pressing (ECAP) at room temperature using route A, route C and route Bc, respectively. Mechanical properties and fracture modes of as-annealed and ECAPed samples were investigated. The microhardness of 1050 Al fabricated by ECAP increases by a factor of about 1.5 compared to the as-annealed state. The ultimate tensile strength (UTS) increases significantly after ECAP, while the elongation decreases. But they are strongly dependence on the number of ECAP passes and the pressing route. The UTS and elongation of the samples processed by route Bc are best, consequently, the static toughness U of the samples is enhanced. Besides, all specimens subjected to ECAP deformation failed in a ductile manner.

The New Approach to Produce Al Sheets with UFG Structure Using SPD Processing

2008 ◽  
Vol 584-586 ◽  
pp. 176-181
Author(s):  
N.F. Yunusova ◽  
Rinat K. Islamgaliev ◽  
I.F. Safiullin ◽  
Ruslan Valiev
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
High Strength ◽  
Short Term ◽  
New Approach ◽  
Rolled Material ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Low Temperature Aging ◽  
Temperature Aging

Microstructure and mechanical properties of the ultrafine-grained (UFG) 1421 aluminum alloy processed by equal channel angular pressing (ECAP) have been studied. This UFG material was successfully rolled under the conditions of superplasticity. It was established that the rolled material exhibited not only the enhanced superplasticity, but also high strength retaining initial ductility at room temperature after additional short-term annealing and low-temperature aging.

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