An Analysis of Strength and Ductility of Ultrafine Grained Al Alloys

2009 ◽  
Vol 633-634 ◽  
pp. 165-177 ◽  
Author(s):  
R. Kapoor ◽  
P.S. De ◽  
Rajiv S. Mishra
Keyword(s):  
Uniform Elongation ◽  
Large Fraction ◽  
Rate Sensitivity ◽  
Total Elongation ◽  
Processing Technique ◽  
Equivalent Strain ◽  
Al Alloys ◽  
Coarse Grained ◽  
Analytical Prediction ◽  
Ultrafine Grained

This paper brings together and compares data of various ultrafine grained (UFG) Al alloys processed through different routes. In general, the trend of decreasing ductility with increasing strength was observed for the UFG alloys. As compared to the coarse grained (CG) alloys, the UFG alloys show a lower ductility, a lower extent of work-hardening and a lower uniform elongation. Unlike the CG alloys, which show a large fraction of uniform to total elongation, in UFG alloys this fraction varies with processing technique. It is shown here that aging of some UFG Al alloys improves ductility. Further, it is shown that increasing the equivalent strain of pre-deformation increases ductility. From this it was inferred that high angle grain boundaries have an important influence on ductility. The variation of ductility with strain rate sensitivity has been found to match both the analytical prediction as well as data of various materials.

scholarly journals Comparison on Tensile Characteristics of Plain C–Mn Steel with Ultrafine Grained Ferrite/Cementite Microstructure and Coarse Grained Ferrite/Pearlite Microstructure

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2309
Author(s):  
Yan Tian ◽  
Mingchun Zhao ◽  
Wenjian Liu ◽  
Jimou Zhang ◽  
Min Zhang ◽  
...  
Keyword(s):  
Uniform Elongation ◽  
Tensile Tests ◽  
Total Elongation ◽  
Microstructural Change ◽  
Coarse Grained ◽  
Lower Yield ◽  
Thermal Component ◽  
Ultrafine Grained ◽  
Athermal Component ◽  
Mn Steel

This work investigated the tensile characteristics of plain C–Mn steel with an ultrafine grained ferrite/cementite (UGF/C) microstructure and coarse-grained ferrite/pearlite (CGF/P) microstructure. The tensile tests were performed at temperatures between 77 K and 323 K. The lower yield and the ultimate tensile strengths were significantly increased when the microstructure was changed from the CGF/P to the UGF/C microstructures, but the total elongation and the uniform elongation decreased. A microstructural change from the CGF/P microstructure to the UGF/C microstructure had an influence on the athermal component of the lower yield and the ultimate tensile strengths but not on the thermal component. The UGF/C microstructure with a higher carbon content provided a higher strength without losing ductility because cementite particles restrained necking.

Grain Refinement and Deformation Behavior of Ultrafine Grained Pd and Pd-Ag Alloys Produced by HPT

2008 ◽  
Vol 584-586 ◽  
pp. 182-187
Author(s):  
Lilia Kurmanaeva ◽  
Yulia Ivanisenko ◽  
J. Markmann ◽  
Ruslan Valiev ◽  
Hans Jorg Fecht
Keyword(s):  
Mechanical Properties ◽  
Deformation Behavior ◽  
Materials Science ◽  
High Pressure Torsion ◽  
Uniform Elongation ◽  
Grain Structure ◽  
Coarse Grained ◽  
Ultrafine Grain ◽  
Ultrafine Grained ◽  
Ultrafine Grain Structure

Investigations of mechanical properties of nanocrystalline (nc) materials are still in interest of materials science, because they offer wide application as structural materials thanks to their outstanding mechanical properties. NC materials demonstrate superior hardness and strength as compared with their coarse grained counterparts, but very often they possess a limited ductility or show low uniform elongation due to poor strain hardening ability. Here, we present the results of investigation of the microstructure and mechanical properties of nc Pd and Pd-x%Ag (x=20, 60) alloys. The initially coarse grained Pd-x% Ag samples were processed by high pressure torsion, which resulted in formation of homogenous ultrafine grain structure. The increase of Ag contents led to the decrease of the resulted grain size and change in deformation behavior, because of decreasing of stacking fault energy (SFE). The samples with larger Ag contents demonstrated the higher values of hardness, yield stress and ultimate stress. Remarkably the uniform elongation had also increased with increase of strength.

Unique Mechanical Properties of Nanostructured Metals

2007 ◽  
Vol 7 (11) ◽  
pp. 3765-3770 ◽  
Author(s):  
Nobuhiro Tsuji
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Grain Size ◽  
Equivalent Strain ◽  
Coarse Grained ◽  
Roll Bonding ◽  
Nanostructured Metals ◽  
Ultrafine Grained ◽  
Nanocrystalline Structures ◽  
Rolling Deformation

Recently, it becomes possible to fabricate bulk metals having ultrafine grained or nanocrystalline structures of which grain size is in nano-meter dimensions. One of the promising ways to realize bulk nanostructured metals is severe plastic deformation (SPD) above logarithmic equivalent strain of 4. We have developed an original SPD process, named Accumulative Roll Bonding (ARB) using rolling deformation in principle, and have succeeded in fabricating bulk nanostructured sheets of various kinds of metals and alloys. The ARB process and the nanostructured metals fabricated by the ARB are introduced in this paper. The nanostructured metals sometimes perform quite unique mechanical properties, that is rather surprising compared with conventionally coarse grained materials. The unique properties seem to be attributed to the characteristic structures of the nano-metals full of grain boundaries.

Enhanced mechanical properties in ultrafine grained 7075 Al alloy

2005 ◽  
Vol 20 (2) ◽  
pp. 288-291 ◽  
Author(s):  
Y.H. Zhao ◽  
X.Z. Liao ◽  
Y.T. Zhu ◽  
R.Z. Valiev
Keyword(s):  
Mechanical Properties ◽  
Natural Aging ◽  
Al Alloys ◽  
Coarse Grained ◽  
Tensile Yield Strength ◽  
Al Alloy ◽  
Aged Sample ◽  
Angular Pressing ◽  
7075 Al Alloy ◽  
Ultrafine Grained

Highest strength for 7075 Al alloy was obtained by combining the equal-channel-angular pressing (ECAP) and natural aging processes. The tensile yield strength and ultimate strength of the ECAP processed and naturally aged sample were 103% and 35% higher, respectively, than those of the coarse-grained 7075 Al alloy counterpart. The enhanced strength resulted from high densities of Guinier–Preston (G-P) zones and dislocations. This study shows that severe plastic deformation has the potential to significantly enhance the mechanical properties of precipitate hardening 7000 series Al alloys.

scholarly journals Texture and Boundary Characteristics of Severely Deformed and Recrystallized Copper

2007 ◽  
Vol 558-559 ◽  
pp. 177-182 ◽  
Author(s):  
Chris H.J. Davies ◽  
Wen Quan Cao ◽  
Cheng Fan Gu ◽  
Rimma Lapovok ◽  
Elena V. Pereloma
Keyword(s):  
Room Temperature ◽  
Equal Channel Angular Extrusion ◽  
Texture Evolution ◽  
Large Fraction ◽  
Cube Texture ◽  
Coarse Grained ◽  
Fine Grain ◽  
Coarse Grained Sample ◽  
Ultrafine Grained ◽  
Boundary Characteristics

Oxygen-free high conductivity copper was subjected to room temperature equal channel angular extrusion of 8 passes using route Bc. The resulting ultra-fine grain copper was then rolled to thickness reductions of up to 96.5% at liquid nitrogen temperatures. Annealed coarse grained copper was rolled to the same strain at room temperature for comparison. Samples from the two routes were isochronally and isothermally annealed, and the microstructure and texture evolution studied by electron back scattered diffraction and x-ray diffraction. Annealing of the ultrafine grained copper led to the development of a strong rotated cube texture from a texture in the rolled material dominated by the Brass component. In contrast the more commonly observed cube texture was found after annealing of the coarse-grained sample. Accompanying the rotated cube texture was the development of a large fraction of boundaries with rotation angle/axis close to 60° <111>.

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.

Strain rate sensitivity and deformation activation volume of coarse-grained and ultrafine-grained TiNi alloys

2015 ◽  
Vol 102 ◽  
pp. 99-102 ◽  
Author(s):  
D.V. Gunderov ◽  
G. Maksutova ◽  
A. Churakova ◽  
A. Lukyanov ◽  
A. Kreitcberg ◽  
...  
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Activation Volume ◽  
Rate Sensitivity ◽  
Coarse Grained ◽  
Ultrafine Grained

Temperature Effects on the Mechanical Behavior of Ultrafine-Grained Material

2010 ◽  
Vol 667-669 ◽  
pp. 827-832
Author(s):  
Tao Suo ◽  
Yu Long Li ◽  
Feng Zhao ◽  
Kui Xie
Keyword(s):  
Flow Stress ◽  
Strain Hardening ◽  
Dynamic Compression ◽  
True Strain ◽  
Rate Sensitivity ◽  
Testing Temperature ◽  
Coarse Grained ◽  
Pressing Method ◽  
Ultrafine Grained ◽  
Strain Hardening Rate

The quasi-static and dynamic compression experiments of ultrafine-grained copper fabricated by equal channel angular pressing method were performed at temperatures ranging from 77 to 573K. The influence of temperature on flow stress, strain hardening rate and strain rate sensitivity were investigated. The results show that the flow stress of ultrafine-grained copper shows much larger sensitivity to testing temperature than that of coarse grained copper. However, the temperature sensitivity of ultrafine-grained copper to true strain is comparative weaker than that of coarse grained copper. For the ultrafine-grained copper, both the strain hardening rate and its sensitivity to temperature of ultrafine-grained copper are lower than those of its coarse counterpart. The SRS also displays apparent dependence on temperature. The activation volume for UFG-Cu is estimated to be on the order of ~10b3 in current experiment temperature. It is suggested that the dislocation-grain boundary interactions process might be the dominant thermally activated mechanism for UFG-Cu.

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