Microstructural Evolution of an Ultrafine-grained Cryomilled Al 5083 Alloy During Thermomechanical Processing

2005 ◽  
Vol 20 (8) ◽  
pp. 2117-2126 ◽  
Author(s):  
David Witkin ◽  
Bing Q. Han ◽  
Enrique J. Lavernia
Keyword(s):  
Grain Size ◽  
Stress State ◽  
Thermomechanical Processing ◽  
Extrusion Process ◽  
Coarse Grained ◽  
Duplex Microstructure ◽  
Ultrafine Grained ◽  
Average Grain Size ◽  
Coarse Grains ◽  
Al 5083 Alloy

The microstructural changes in cryomilled and consolidated Al 5083 following compression testing at several temperatures are described. Prior to testing, the material had an average grain size of approximately 138 nm and exhibited a duplex microstructure, containing coarse grains between 500 and 2000 nm. After uniaxial compressive deformation at temperatures between 423 and 573 K (0.49–0.66 Tm), the average grain size increased to between 200 and 300 nm, consistent with the average grain size of extrusions formed from the same material at similar temperatures. The similarity in grain size distribution following uniaxial compression or extrusion despite differences in total strain and stress state imposed by each indicates that much of the deformation in the extrusion process occurs in coarse-grained regions.

Ultrafine-Grained Structure Produced by FSW and ECAP in Al-Mg-Sc-Zr Alloy: Comparison

2016 ◽  
Vol 838-839 ◽  
pp. 379-384 ◽  
Author(s):  
Vladislav Kulitskiy ◽  
Sergey Malopheyev ◽  
Yulia Buranova ◽  
Sergiy V. Divinski ◽  
Gerhard Wilde ◽  
...  
Keyword(s):  
Grain Size ◽  
Rotation Speed ◽  
Coarse Grained ◽  
Friction Stir ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Average Grain Size ◽  
The Matrix ◽  
Average Size ◽  
Tool Rotation

The Al-5.4Mg-0.2Sc-0.1Zr alloy with initial coarse grained structure and containing coherent nanoscale Al3(Sc,Zr) particles with an average size of ~9 nm was subjected to equal channel angular pressing (ECAP) at temperatures ranging from 300 to 450°C up to a total strain of ~12 and friction stir processing (FSP) with the rotation speed ranging from 350 to 800 rpm. ECAP led to the formation of a uniform microstructure with an average grain size of ~ 0.9 μm. Increasing deformation temperature leads to a slight increase in the average grain size to 1.4 μm and coarsening of Al3(Sc,Zr) precipitates to 13 nm. FSP with a tool rotation speed of 350, 500, 650, 800 rpm and traveling speed of 75 mm/min led to the formation of fully recrystallized uniform microstructures with an average grain size of ~1.6, 1.9, 2.7 and 2.9 μm, respectively. The coarsening of Al3(Sc,Zr) dispersoids from 9 to 27 nm occurred under FSP but most of them retained coherency with the matrix.

Microstructure Evolution and Mechanical Properties of Titanium Nickelide during Pressing in Equal-Channel Angular Matrix with Quasi-Small Angle of Channels Intersection

2021 ◽  
Vol 410 ◽  
pp. 123-127
Author(s):  
Abdrakhman B. Naizabekov ◽  
Dmitry V. Kuis ◽  
Andrey V. Kasperovich
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Microstructure Evolution ◽  
Small Angle ◽  
Titanium Nickelide ◽  
Coarse Grained ◽  
Ultrafine Grained Structure ◽  
Ultrafine Grained ◽  
Average Grain Size

The article presents the results of the analysis of the microstructure and mechanical properties of titanium nickelide formed during pressing in an equal-channel angular matrix with a quasi-small angle of channels intersection. The conducted studies have shown that pressing in an equal-channel angular matrix with a quasi-small angle of channels intersection ensures the formation of a homogeneous sub-ultrafine-grained structure in the titanium nickelide alloy, while the average grain size, decreasing by 100-200 times, is 0.3-0.5 microns, and the tensile strength increases to 1350 MPa in 6 passes, which is almost 90% higher than in the coarse-grained quenched state.

Preparation and Tensile Property of Nanostructured Cu-Ag Alloy with Bimodal Grain Size Distribution

2017 ◽  
Vol 727 ◽  
pp. 432-437
Author(s):  
Ying Guang Liu ◽  
Shi Bing Zhang ◽  
Zhong He Han ◽  
Xiao Yan Zhu
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Volume Fraction ◽  
Tensile Deformation ◽  
Coarse Grained ◽  
Average Grain Size ◽  
Coarse Grains ◽  
Bimodal Grain Size ◽  
Bimodal Grain Size Distribution

Nanostructured Cu-Ag alloys with bimodal grain size distribution were prepared and their tensile deformation behaviors were studied. The alloys were processed by hot isostatic pressing of blends of nanoand micrometer-sized powder particles. The microstructure of the alloys consisted of nanograins with an average grain size of 40 nm and coarse-grains with an average grain size of 30 um. The bimodal structured alloy exhibited high tensile strengths 522 MPa and a large plastic strain to failure approximately 30%. Simultaneously, Their tensile stress-strain curves displayed a long work-hardening region, and their tensile ductility increased with increasing coarse-grained volume fraction. The high strength primarily results from the contribution of nanograins, while the enhanced ductility may be attributed to the improved strain hardening capability by the presence of coarse grains.

scholarly journals Influence of Steel Grain Size on Residual Stress in Grinding Processing

2010 ◽  
Vol 638-642 ◽  
pp. 2389-2394 ◽  
Author(s):  
Masahide Gotoh ◽  
Katsuhiro Seki ◽  
M. Shozu ◽  
Hajime Hirose ◽  
Toshihiko Sasaki
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Grain Size ◽  
Stress State ◽  
Mechanical Grinding ◽  
Fine Grained ◽  
Residual Stress State ◽  
Analysis Methods ◽  
Average Grain Size ◽  
Fine Grained Steels

The fine-grained rolling steels NFG600 and the conventional usual rolling steels SM490 were processed by sand paper polishing and mechanical grinding to compare the residual stress generated after processing. The average grain size of NFG600 and SM490 is 3 μm and 15μm respectively. Therefore improvement of mechanical properties for such fine-grained steels is expected, it is important to understand the residual stress state of new fine-grained materials with processing. In this study, multi axial stresses of two kinds of specimens after polishing and grinding were measured by three kinds of analysis methods including cos-ψ method. As a result, as for σ33, the stress of NFG was compression, though that of SM490 was tension.

Thermal Stability of Ultrafine-Grained Pure Titanium Processed by High-Pressure Torsion

2021 ◽  
Vol 1016 ◽  
pp. 338-344
Author(s):  
Wan Ji Chen ◽  
Jie Xu ◽  
De Tong Liu ◽  
De Bin Shan ◽  
Bin Guo ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Grain Size ◽  
High Pressure ◽  
Annealing Temperature ◽  
High Pressure Torsion ◽  
Stored Energy ◽  
Ultrafine Grained ◽  
Average Grain Size ◽  
Thermal Stability Of

High-pressure torsion (HPT) was conducted under 6.0 GPa on commercial purity titanium up to 10 turns. An ultrafine-grained (UFG) pure Ti with an average grain size of ~96 nm was obtained. The thermal properties of these samples were studied by using differential scanning calorimeter (DSC) which allowed the quantitative determination of the evolution of stored energy, the recrystallization temperatures, the activation energy involved in the recrystallization of the material and the evolution of the recrystallized fraction with temperature. The results show that the stored energy increases, beyond which the stored energy seems to level off to a saturated value with increase of HPT up to 5 turns. An average activation energy of about 101 kJ/mol for the recrystallization of 5 turns samples was determined. Also, the thermal stability of the grains of the 5 turns samples with subsequent heat treatments were investigated by microstructural analysis and Vickers microhardness measurements. It is shown that the average grain size remains below 246 nm when the annealing temperature is below 500 °C, and the size of the grains increases significantly for samples at the annealing temperature of 600 °C.

scholarly journals A 2.9 GPa Strength Nano-Grained and Nano-Precipitated 304L-Type Austenitic Stainless Steel

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5382
Author(s):  
Congcong Du ◽  
Guoying Liu ◽  
Baoru Sun ◽  
Shengwei Xin ◽  
Tongde Shen
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Yield Strength ◽  
Average Particle Size ◽  
Coarse Grained ◽  
Average Particle ◽  
Dispersion Strengthening ◽  
Ultrafine Grained ◽  
Average Grain Size ◽  
Bulk Nanocrystalline

Austenitic stainless steel has high potential as nuclear and engineering materials, but it is often coarse grained and has relatively low yield strength, typically 200–400 MPa. We prepared a bulk nanocrystalline lanthanum-doped 304L austenitic stainless steel alloy by a novel technique that combines mechanical alloying and high-pressure sintering. The achieved alloy has an average grain size of 30 ± 12 nm and contains a high density (~1024 m−3) of lanthanum-enriched nanoprecipitates with an average particle size of approx. 4 nm, leading to strong grain boundary strengthening and dispersion strengthening effects, respectively. The yield strength of nano-grained and nano-precipitated stainless steel reaches 2.9 GPa, which well exceeds that of ultrafine-grained (100–1000 nm) and nano-grained (<100 nm) stainless steels prepared by other techniques developed in recent decades. The strategy to combine nano-grain strengthening and nanoprecipitation strengthening should be generally applicable to developing other ultra-strong metallic alloys.

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-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.

Influence of Grain Size on Mechanical Properties in a Fe-9Ni-12Mn-2.5Si-1.0C TWIP Steel

2011 ◽  
Vol 197-198 ◽  
pp. 655-661
Author(s):  
Ze Bin Yang ◽  
Ding Yi Zhu ◽  
Wei Fa Yi ◽  
Shu Mei Lin ◽  
Cheng Mei Du
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Strain Hardening ◽  
Twip Steel ◽  
Optical Microscope ◽  
Coarse Grained ◽  
Microstructure Observation ◽  
Transmission Electron ◽  
Average Grain Size

We investigate the influence of grain size on mechanical properties in a Fe-9Ni-12Mn-2.5Si-1.0C TWIP steel by unidirectional tensile. Meanwhile the microstructures of the TWIP steel were observed and analyzed by optical microscope (OM) and transmission electron microscope (TEM). The experimental results show that the TWIP steel’s yield strength and tensile strength decrease with the increasing of grain size, whereas the plasticity increases with it. When the average grain size reaches to 27μm, the tensile strength is 1080MPa, the elongation percentage is 77%, and the strength-plasticity product achieves the 83160MPa•%. Steel’s strain hardening rate can be changed from three-stage to four-stage with the increasing of grain sizes, the areas of strain hardening by twin deformation mechanism are expanded. Through the microstructure observation we found that, coarse-grained TWIP steel conducts to twinning formation, the high density twins can increase the alloy’s ductility by splitting the grain.

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.

Sign in / Sign up

Export Citation Format

Share Document