The Effect of Grain Size on Superplastic Deformation of Ti-6Al-4V Alloy

2007 ◽  
Vol 551-552 ◽  
pp. 387-392 ◽  
Author(s):  
Wen Juan Zhao ◽  
Hua Ding ◽  
D. Song ◽  
F.R. Cao ◽  
Hong Liang Hou
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Superplastic Deformation ◽  
Initial Strain Rate ◽  
Deformation Mode ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Coarse Grained ◽  
Transmission Electron ◽  
Grain Growth Model

In this study, superplastic tensile tests were carried out for Ti-6Al-4V alloy using different initial grain sizes (2.6 μm, 6.5μm and 16.2 μm) at a temperature of 920°C with an initial strain rate of 1×10-3 s-1. To get an insight into the effect of grain size on the superplastic deformation mechanisms, the microstructures of deformed alloy were investigated by using an optical microscope and transmission electron microscope (TEM). The results indicate that there is dramatic difference in the superplastic deformation mode of fine and coarse grained Ti-6Al-4V alloy. Meanwhile, grain growth induced by superplastic deformation has also been clearly observed during deformation process, and the grain growth model including the static and strain induced part during superplastic deformation was utilized to analyze the data of Ti-6Al-4V alloy.

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.

Ultrafine-Grained Steel Produced by Warm Rolling and Annealing of Lath Martensite

2010 ◽  
Vol 667-669 ◽  
pp. 863-866
Author(s):  
Xin Zhao ◽  
Xiao Ling Yang
Keyword(s):  
Lath Martensite ◽  
Tensile Tests ◽  
Total Elongation ◽  
Optical Microscope ◽  
Warm Rolling ◽  
Steel Plates ◽  
Transmission Electron ◽  
Hardness Tests ◽  
Ultrafine Grained ◽  
Ultrafine Grained Steel

Steel plates with lath martensite microstructure were rolled up to 68% reduction at 673 K and then annealed at 473-973 K. The microstructure evolution was studied by using an optical microscope and a transmission electron microscopy. And the properties were investigated by using tensile tests and hardness tests. Results show that ultrafine grains + nano-carbides are obtained in the steel plates. The specimen annealed at 823 K has a good combination of strength and ductility. The tensile strength and total elongation are 1028 MPa and 7.2%, respectively. And the hardness is 338 Hv.

Transverse Superplastic Deformation of Laser Welded Ti-6Al-4V Sheet

2011 ◽  
Vol 291-294 ◽  
pp. 1440-1443 ◽  
Author(s):  
Dong Hai Cheng ◽  
Ye Ping Zhou ◽  
Qiang Wei ◽  
Yi Ping Chen ◽  
De An Hu
Keyword(s):  
Strain Rate ◽  
Weld Joint ◽  
Superplastic Deformation ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Weld Bead ◽  
Uniform Deformation ◽  
Before And After ◽  
Acicular Structure

Uni-axial hot tensile tests were used to investigate the transverse superplastic deformation of laser welded Ti-6Al-4V sheet. Microstructures of the weld bead before and after superplastic deformation were observed by optical microscope. The maximal deformation of 46% was obtained on weld joint at strain rate of 10−2s−1 and temperature of 1173K. A coefficient K was introduced to evaluate the non-uniform deformation of weld joint. After superplastic deformation the microstructure of weld bead transformed into lamellas from original acicular structure.

Annealing Treatment for Superplastic Forming of Twin Roll Casted AZ31 Magnesium Sheet

2011 ◽  
Vol 239-242 ◽  
pp. 50-54 ◽  
Author(s):  
Guo Dong Shi ◽  
Jun Qiao
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Mechanical Test ◽  
Dynamic Balance ◽  
Annealing Treatment ◽  
Optical Microscope ◽  
Grain Structure ◽  
Average Grain Size ◽  
Az31 Sheet ◽  
Twin Roll

Annealing treatments at 200°C, 250 °C, 300°C, and 350°C were conducted on a twin-roll casted AZ31 sheet with an initial average grain size of 10.11 mm. Microstructure and mechanical behaviors were studied by optical microscope observation and tensile mechanical test. Expermeintal results show that grain size experienced three stage evolution during 180 min annealing at each temperature: recrystallization refinement, stabilization under dynamic balance of recrystallization and grain growth, and grain growth. The minimum average grain size of 5.96 μm was achieved after 120 min annealing at 200°C. The refined grain structure causes a decrease of ultimate tensile strength and an increase of elongation, and facilitates superplastic deformation of the material.

Microstructural Evolution of a Commercial 0.04%C Steel During Batch Annealing

2006 ◽  
Vol 509 ◽  
pp. 17-24
Author(s):  
J.C. Millán ◽  
A.L. Rivas ◽  
Jose María Cabrera ◽  
Sonia Camero ◽  
Leo Kestens
Keyword(s):  
Grain Growth ◽  
Microstructural Evolution ◽  
Plastic Anisotropy ◽  
Tensile Tests ◽  
Grain Structure ◽  
Heating Process ◽  
Heating Rates ◽  
Hold Period ◽  
Transmission Electron ◽  
Batch Annealing

The effect of heating rate and annealing time on the microstructure and texture of a commercial 0.04 %C steel, cold rolled up to 80 %, is studied. Samples have been isothermally annealed at various heating rates (12 °C/h, 20 °C/h, 40 °C/h and 650 °C/min) and then soaked at 700 °C for 15 hours. The microstructural evolution of the samples during the heating process and hold period has been followed by optical microscopy, scanning and transmission electron microscopy. The electron back-scattered diffraction technique is used to reveal the texture of the samples. Tensile tests and hardness measurements are correlated with the microstructural features. Results show that (a) recrystallization occurs between 600 and 650 °C; (b) a “pancake” structure develops during recrystallization at low heating rates without appreciable grain growth; (c) samples heated at 650 °C/min exhibit an equiaxed grain structure and significant grain growth; (d) only at low heating rates the material develops a strong {111}<uvw> recrystallization texture, in ccordance with the high plastic anisotropy found by mechanical testing.

Microstructural Evolution of Synthetic Forsterite Aggregates Deformed to High Strain

2004 ◽  
Vol 467-470 ◽  
pp. 579-584 ◽  
Author(s):  
A. Kellermann Slotemaker ◽  
J.H.P. de Bresser ◽  
C.J. Spiers ◽  
M.R. Drury
Keyword(s):  
Grain Size ◽  
Dynamic Recrystallization ◽  
Grain Growth ◽  
Microstructural Evolution ◽  
Large Scale ◽  
High Strain ◽  
Confining Pressure ◽  
Size Reduction ◽  
Coarse Grained ◽  
Fine Grained

Microstructures provide the crucial link between solid state flow of rock materials in the laboratory and large-scale tectonic processes in nature. In this context, microstructural evolution of olivine aggregates is of particular importance, since this material controls the flow of the Earth’s upper mantle and affects the dynamics of the outer Earth. From previous work it has become apparent that if olivine rocks are plastically deformed to high strain, substantial weakening may occur before steady state mechanical behaviour is approached. This weakening appears directly related to progressive modification of the grain size distribution through competing effects of dynamic recrystallization and syn-deformational grain growth. However, most of our understanding of these processes in olivine comes from tests on coarse-grained materials that show grain size reduction through dynamic recrystallization. In the present study we focused on fine-grained (~1 µm) olivine aggregates (i.e., forsterite/Mg2SiO4), containing ~0.5 wt% water and 10 vol% enstatite (MgSiO3), Samples were axially compressed to varying strains up to a maximum of ~45%, at 600 MPa confining pressure and a temperature of 950°C. Microstructures were characterized by analyzing full grain size distributions and textures using SEM/EBSD. We observed syndeformational grain growth rather than grain size reduction, and relate this to strain hardening seen in the stress-strain curves.

scholarly journals Solidification, Microstructure and Mechanical Properties of Mg-2.8Nd-1.5Gd-0.5Zn-0.5Zr Cast Alloy with Erbium Addition

2018 ◽  
Vol 202 ◽  
pp. 01001
Author(s):  
R. Ahmad ◽  
A.M.M. Elaswad ◽  
M. Z. Hamzah ◽  
N. R. Shahizan
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Grain Size ◽  
Cast Alloy ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Microstructure Analysis ◽  
Cooling Curve ◽  
Scanning Electron

The thermal parameters of Mg-2.8Nd-1.5Gd-0.5Zn-0.5Zr cast alloy with 0.25 wt.% of erbium (Er) were evaluated by the computer-aided cooling curve thermal analysis(CA CCTA), whereas the microstructure analysis was investigated by the optical microscope and scanning electron microscopy. Results from the cooling curve and microstructure analysis showed that Er altered the grain size of the alloys. In addition, the grain size was reduced by approximately 19.6% with the addition of Er. Scanning electron microscopy results showed that Er formed an Mg-Zn-Nd-Er phase which distributed along the grain boundaries. Furthermore, the mechanical properties were investigated by hardness and tensile tests with Er addition. The addition of 0.25 wt.% of Er significantly improved the ultimate tensile strength and yield strength. In addition, the hardness value of Mg-2.8Nd-1.5Gd-0.5Zn-0.5Zr increased by 13.9% with Er addition.

scholarly journals Microstructure Evolution and Grain Growth Model of AZ31 Magnesium Alloy under Condition of Isothermal

2015 ◽  
Vol 2015 ◽  
pp. 1-6
Author(s):  
Zhongtang Wang ◽  
Lingyi Wang ◽  
Lizhi Liu
Keyword(s):  
Grain Size ◽  
Magnesium Alloy ◽  
Grain Growth ◽  
Growth Model ◽  
Microstructure Evolution ◽  
Heating Temperature ◽  
Holding Time ◽  
Az31 Magnesium Alloy ◽  
Temperature Range ◽  
Grain Growth Model

Microstructure evolution of AZ31 magnesium alloy in annealing process had been investigated by experiment study at heating temperature range of 150°C–450°C and holding time range of 15 min–60 min. The effects of heating temperature and holding time on grain growth had been analyzed. The results presented that the grain size tends to grow up with the increase of holding time at a certain temperature. At a certain holding time, the grain size increased firstly and then decreased at the heating temperature range of 150–250°C. And when heating temperature is higher than 250°C, the grain grows up gradually with the increase of heating temperature. The grain growth model of AZ31 Mg alloy has been established by regression based on the experimental data at temperature of 250–450°C, and the relative error between model calculation results and experimental results is less than 19.07%. Activation energy of grain growth of AZ31 magnesium alloy had been determined.

Microstructures and Mechanical Properties of Bulk Nanocrystalline Fe3Al Materials With 5, 10 and 15 wt. % Cu Prepared by Aluminothermic Reaction

2011 ◽  
Vol 236-238 ◽  
pp. 2191-2196 ◽  
Author(s):  
Yu Peng Wei ◽  
Pei Qing La ◽  
Mei Dan Que ◽  
Wen Sheng Li ◽  
Yang Yang ◽  
...  
Keyword(s):  
Yield Strength ◽  
Optical Microscope ◽  
Matrix Phase ◽  
Coarse Grained ◽  
Compressive Yield Strength ◽  
Nanocrystalline Phase ◽  
X Ray Diffraction ◽  
Aluminothermic Reaction ◽  
Transmission Electron ◽  
Bulk Nanocrystalline

Bulk nanocrystalline Fe3Al based materials with 5, 10 and 15 wt. % Cu were prepared by aluminothermic reaction in which the melts were superheated about 1600 K before solidification. Microstructures of those materials were investigated by optical microscope, electron probe microanalysis, X-ray diffraction and transmission electron microscope. It was shown that microstructures of the materials consisted of a nanocrystalline matrix phase and a little contamination Al2O3and Fe3AlCxfiber phases. The nanocrystalline matrix phase was composed of Fe, Al and Cu elements and disordered bcc which did not change with content of Cu. Average grain sizes of the nanocrystalline phase of the materials with 5, 10 and 15 wt. % Cu were 18, 24 and 25 nm respectively and that of the material with 5 wt. % Cu was the smallest. Compressive properties of the materials were tested. The material with 5 wt. % Cu has good ductility compared with the materials with 10 and 15 wt. % Cu. Yield strength of the materials was about two times higher than that of coarse grained Fe3Al material. The compressive yield strength of the material with 5 wt. % Cu was higher than those of the materials with 10 and 15 wt. % Cu and its flow stress in compression was up to about 1500 MPa.

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