scholarly journals Superplastic Behaviour of Ti54M and Ti64

2020 ◽  
Vol 321 ◽  
pp. 04028
Author(s):  
Paranjayee Mandal ◽  
Ares Gomez-Gallegos ◽  
Diego Gonzalez ◽  
Hosam Elrakayby ◽  
Paul Blackwell
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Grain Growth ◽  
Superplastic Deformation ◽  
Volume Fraction ◽  
Grain Boundary Sliding ◽  
Superplastic Behaviour ◽  
Average Grain Size ◽  
Lower Temperature ◽  
Superplastic Properties

Even though TIMETAL-54M (Ti-5Al-4V-0.6Mo-0.4Fe or Ti54M) has been commercially available for over 10 years, further study of its superplastic properties is still required in order to assess its applicability within the aerospace industry as a potential replacement for other commercial titanium alloys such as Ti-6Al-4V (Ti64). Ti54M is expected to obtain superplastic characteristics at a lower temperature than Ti64 due to its lower beta-transus temperature. The superplastic forming (SPF) capability of alloys that can be formed at lower temperatures has always attracted the interest of industry as it reduces the grain growth and alpha-case formation, leading to longer life for costly high temperature resistant forming tools. In this work, the SPF characteristics of both Ti54M and Ti64 have been examined by conducting tensile tests according to the ASTM E2448 standard within a range of temperatures and strain values at a fixed strain rate of 1 × 10-4/S. A high strain rate sensitivity and uniform deformation at high strains are key indicators in selecting the optimum superplastic temperature. This was observed at 815˚C and 925˚C for Ti54M and Ti64 respectively. The tensile samples were water quenched to freeze their respective microstructure evolution following superplastic deformation and SEM images were captured for grain size and volume fraction of alpha-phase analyses. A slightly higher alpha-grain growth rate was observed during superplastic deformation of Ti64. The initial fine-grain microstructure of Ti54M (~1.6 micron) resulted in a final microstructure with an average grain size of ~3.4 micron and optimum the alpha/beta ratio. Both the fine-grained microstructure and increased amount of beta-volume fraction promotes the superplastic behaviour of Ti54M by grain boundary sliding (GBS). Thus superplastic properties were observed for Ti54M at a lower temperature (~100˚C) than for Ti64.

Characterization of Zinalco Alloy Superplastically Deformed Using Orientation Imaging Microscopy

2009 ◽  
Vol 1242 ◽  
Author(s):  
Ramos A. Mitsuo ◽  
Martínez F. Elizabeth ◽  
Negrete S. Jesús ◽  
Torres-Villaseñor G.
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Superplastic Deformation ◽  
Orientation Imaging Microscopy ◽  
Grain Boundary Sliding ◽  
Boundary Misorientation ◽  
Average Grain Size ◽  
Grain Boundary Misorientation ◽  
Misorientation Angles

ABSTRACTZinalco alloy (Zn-21mass%Al-2mass%Cu) specimens were deformed superplastically with a strain rate (ε) of 1×10-3 s-1 at homologous temperature (TH) of 0.68 (5 ). It was observed neck formation that indicate nonhomegeneus deformation. Grain size and grain boundaries misorientation changes, due superplastic deformation, were characterized by Orientation Imagining Microscopy (OIM) technique. It was studied three regions in deformed specimens and the results were compared with the results for a specimen without deformation. Average grain size of 1 mm was observed in non-deformed specimen and a fraction of 82% for grain boundary misorientation angles with a grain boundaries angles between 15° and 55° was found. For deformed specimen, the fraction of angles between 15° and 55° was decreced to average value of 75% and fractions of low angle (<5°) and high angle (>55°) misorientations were 10% and 15% respectively. The grain size and high fraction of grain boundary misorientation angles between 15° and 55° observed in the alloy without deformation, are favorable for grain rotation and grain boundary sliding (GBS) procces. The changes observed in the fraction of favorable grain boundary angles during superplastic deformation, shown that the superplastic capacity of Zinalco was reduced with the deformation.

Microstructural Evolution of a Fine-Grained Mg-Y-Nd Alloy during Superplastic Deformation

2016 ◽  
Vol 849 ◽  
pp. 162-167
Author(s):  
Geng Hua Cao ◽  
Da Tong Zhang
Keyword(s):  
Electron Microscopy ◽  
Strain Rate ◽  
Superplastic Deformation ◽  
Grain Boundary Sliding ◽  
Second Phase ◽  
Friction Stir ◽  
Fine Grained ◽  
Average Grain Size ◽  
Temperature Ranges ◽  
Increasing Temperature

Cast Mg-4.27Y-2.94Nd-0.51Zr (wt.%) alloy was subjected to submerged friction stir processing (SFSP) with at a rotation rate of 600 rpm and a traveling speed of 60 mm min-1. Superplastic behavior of specimens with an average grain size of ~1.3 μm were investigated in the temperature ranges of 683-758 K and the strain rate ranges from 1×10-1 to 4×10-4 s-1. Microstructure characteristics were investigated by optical microscopy, scanning electron microscopy and transmission electron microscopy. The results show that the maximum elongation of 967% was obtained at 733 K and 3×10-3 s-1, the optimal HSRS of 900% achieved at 758 K and 2×10-2 s-1. Grains and second phase particles grew coarser with the increasing temperature or decreasing strain rate. Remarkable grain growth is the main reason that elongations are all significantly decreased when the strain rate decrease from 3×10-3 s-1 to 4×10-4 s-1. Grain boundary sliding is the main mechanism during superplastic deformation.

Superplasticity and Microstructural Evolution of a Large-Grained Mg Alloy

2000 ◽  
Author(s):  
Yi Liu ◽  
Kelly Shue ◽  
Xin Wu ◽  
Zhicheng Li ◽  
Yongbo Xu
Keyword(s):  
Grain Size ◽  
Electron Microscope ◽  
Strain Rate ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Large Angle ◽  
Dislocation Creep ◽  
Rate Dependent ◽  
Average Grain Size ◽  
Elongation To Failure

Abstract Commercial Mg-3Al-Zn alloys (AZ31) with initial large grains (∼250μm) has been found superplastic at a strain rate of 0.5×10−2s−1 and at 350–500 C. The maximum elongation to failure of 170% at 500°C was obtained. Scanning electron microscope observations with electron back-scattering diffraction technique (SEM-EBSD) indicate that during deformation significant grain size reduction occurred, the average grain size reduced from about 250μm before deformation to about 50μm after deformation at temperatures from 300 C to 400°C, it reduced to about 100μm if deformed at above 400°C. The observed grain refinement at lower temperature and grain growth at higher temperature during the superplastic deformation is believed to be the result of the competing processes between dynamic recrystallization and dynamic grain growth, which are temperature and strain rate dependent. Transmission electron microscope (TEM) observations indicates that most of the grain boundaries are large-angle grain boundaries, though small amount of small-angle grain boundaries are also observed. The density of dislocations in the grains is very low in these superplasticlly deformed samples. It is evident that grain boundary played a role as the source and sink of the dislocation, being responsible for combined dislocation creep and diffusional creel. Therefore, the very large elongation obtained at the very high strain rates and high temperatures is attributed to dynamic dislocation hardening, recovery and recrystallization.

Heat Treatment of Ti2AlNb Intermetallic and its Superplastic Properties

2007 ◽  
Vol 551-552 ◽  
pp. 453-456 ◽  
Author(s):  
He Ping Guo ◽  
Zhi Qiang Li
Keyword(s):  
Heat Treatment ◽  
Elevated Temperature ◽  
Strain Rate ◽  
Hot Rolling ◽  
Superplastic Deformation ◽  
Volume Fraction ◽  
Grain Structure ◽  
Maximum Elongation ◽  
Superplastic Properties ◽  
Equiaxed Grain

Ti2AlNb orthorhombic alloys exhibit great potential as advanced aerospace and structural materials serviced at elevated temperature. In this paper, pre-heat treatment of as-received hot rolling Ti-22Al-25Nb alloy was conducted. Fine, stable and equiaxed grain structure was obtained by the pre-heat treatment. The volume fraction of B2 increased when annealing at 980°C. The Ti-22Al-25Nb alloy showed characteristics of superplastic deformation when tested at 960°C. Maximum elongation of 280% has been obtained at strain rate of 1.0×10-4s-1.

The Effect of Small Amounts of Yttrium Addition on Static and under Superplastic Deformation Grain Growth in Newly Developed α+β Type, Ti-4.5Al-6Nb-2Mo-2Fe Alloy

2006 ◽  
Vol 15-17 ◽  
pp. 970-975 ◽  
Author(s):  
Behrang Poorganji ◽  
S. Hotta ◽  
Taichi Murakami ◽  
Takayuki Narushima ◽  
Yasutaka Iguchi ◽  
...  
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Grain Growth ◽  
Hot Deformation ◽  
Superplastic Deformation ◽  
Superplastic Forming ◽  
Growth Behavior ◽  
Two Phase ◽  
Yttrium Addition ◽  
Grain Growth Behavior

New α+β type titanium alloy with Ti-4.5Al-6Nb-2Mo-2Fe was developed on the basis of using biocompatible elements and eliminating the cytotoxic ones such as Vanadium, while achieving the desirable mechanical properties such as appropriate strength, cold workability and low superplastic forming (SPF) temperature. The present study was conducted to investigate the effect of yttrium addition of less than 0.05% into this alloy on static and under superplastic deformation grain growth behavior. The new alloy bar manufactured by α+β processing and annealed at 1073K yielded extremely fine two-phase microstructure with α grain size around 2μm. Specimens were heated at temperatures of 1048, 1073 and 1098K and kept for times between 3.6 to 172.8KS. Yttrium forms in-situ Y2O3 particles, and the presence of these particles yield finer two phase microstructure due to their retardation effect on β phase grain growth. Grain growth behavior during hot deformation was investigated by hot compression test in use of a hot working simulator of THERMEC-Master Z. Strain rate was varied from 2×10-2 to 2×10-4S-1 and strain was 0.69. Grain size of both α and β phases increased with a reduction of strain rate, and Y2O3 particle was also effective to retard grain growth under hot deformation. It was confirmed from comparison of grain growth during isothermal heating with and without hot deformation that grain growth was much accelerated by deformation. All of these results were discussed based on grain growth mechanism or model for two-phase microstructures as well as superplastic deformation mechanism.

Superplastic Deformation Mechanisms in a Fine-Grained, Yttria-stabilized Tetragonal Zirconia Polycrystal (Y-TZP)

1990 ◽  
Vol 196 ◽  
Author(s):  
T. G. Nieh ◽  
J. Wadsworth
Keyword(s):  
Grain Boundary ◽  
Strain Rate ◽  
Grain Growth ◽  
Strain Rate Sensitivity ◽  
Superplastic Deformation ◽  
Rate Sensitivity ◽  
Grain Boundary Sliding ◽  
Boundary Triple ◽  
Sliding Mechanism ◽  
Boundary Sliding

ABSTRACTConcurrent grain growth, and in particular, dynamic grain growth, was observed to take place during superplastic deformation of Y-TZP. As a result of this concurrent grain growth, the measured strain rate sensitivity was found to be lower than that measured under constantstructure conditions. In the present paper, data obtained from the superplastic deformation of YTZP under constant-structure conditions are presented. It is demonstrated that the strain rate sensitivity values are generally higher than 0.5, when measured from the grain size-compensated data; this result suggests a grain boundary sliding mechanism. Microstructures from samples prior to and after superplastic deformation reveal grains which are essentially equiaxed; this observation is also consistent with a grain boundary sliding mechanism. Both high-resolution images of grain boundary triple points using transmission electron microscopy, and fracture surface studies using Auger electron spectroscopy and X-ray photoelectron spectroscopy indicate that there is no evidence for the presence of glassy phases at grain boundaries in Y-TZP.

Numerical Simulation of Hot Forging for the Disc of Superalloy GH4169

2011 ◽  
Vol 328-330 ◽  
pp. 1598-1601
Author(s):  
Yan Shu Zhang ◽  
Xiao Fei Liu
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Volume Fraction ◽  
Hot Forging ◽  
Pure Titanium ◽  
Constant Strain Rate ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Stress Strain ◽  
Average Grain Size

In this paper, the hot deformation behavior of GH4169 superalloy were investigated at temperature of 900-1020°C and at strain rate of 0.001-0.1up to a 60% height reduction of the sample using isothermal constant strain rate compression tests on process annealed material. The high temperature deformation behaviour of pure titanium was characterized based on an analysis of the stress–strain curves The proposed constitutive equation and the stress-strain curves were implanted into DEFORM2D, a hot forging process for the disc of GH4169 was simulated, and the micro-variable, recrystallized volume fraction, average grain size, recrystallized grain size and etc., were plotted with a contoured figure. According to the comparision between the experimental and predicted result, the absolute error between them is acceptable. The method for microstructure prediction will be significant to the engineering.

Microstructural Evolution during Superplastic Deformation in Large-grained Iron Aluminides

1998 ◽  
Vol 552 ◽  
Author(s):  
Dongliang Lin ◽  
Yi Liu
Keyword(s):  
Grain Size ◽  
Superplastic Deformation ◽  
Grain Boundary Sliding ◽  
Iron Aluminides ◽  
High Angle ◽  
Superplastic Behavior ◽  
Dislocation Glide ◽  
Fine Grain ◽  
Transmission Electron ◽  
Average Grain Size

ABSTRACTSuperplastic behavior has been found in Fe3A1 and FeAl alloys with grain sizes of 100–600μm. The large-grained Fe3Al and FeAl alloys exhibit all deformation characteristics of conventional fine size superplastic alloys. However, superplastic behavior was found in large-grained iron aluminides without the usual pre-requisites for superplasticity of a fine grain size and grain boundary sliding. The metallographic examinations have shown that the average grain size of large-grained iron aluminides decreased during superplastic deformation. Transmission electron microscopy (TEM) observations have shown that there were a great number of subgrain boundaries which formed a network and among which the proportion of low and high angle boundaries increased with increased strain. The observed superplastic phenomenon is explained by continuous recovery and recrystallization. During superplastic deformation, an unstable subgrain network forms and these subboundaries absorb gliding dislocations and transform into low and high angle grain boundaries. A dislocation glide and climb process accommodated by subboundary sliding, migration and rotation, allows the superplastic flow to proceed

High Strain Rate Superplastic Deformation Behavior of TiNP/2014Al Composite

2010 ◽  
Vol 97-101 ◽  
pp. 1633-1636
Author(s):  
Hui E Hu ◽  
Liang Zhen
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Superplastic Deformation ◽  
High Strain ◽  
Volume Fraction ◽  
Tensile Tests ◽  
Grain Boundary Sliding ◽  
Powder Metallurgy Method ◽  
Accommodation Mechanism

TiNP/2014Al composite was prepared by powder metallurgy method with a reinforcement volume fraction of 15%. High strain rate superplastic deformation behavior of the TiNP/2014Al composite was investigated by tensile tests conducted at 818 K with different strain rates range from 1.7×100 to 1.7×10-3 s-1, DSC, OM, TEM and SEM. It is shown that a maximum elongation of 351% is achieved at 818 K and 3.3×10-1 s-1. The curve of value can be divided into two stages with the variation of strain rate and the critical strain rate is 10-1 s-1. Plastic deformation of the TiNP/2014Al composite at 818 K and 3.3×10-1 s-1 is conducted at an almost constant maximum value of flow stress. High strain rate superplastic deformation mechanism of the TiNP/2014Al composite deformed at 818 K with the strain rate of 3.3×10-1 s-1 is grain boundary sliding accommodation mechanism plus liquid phase helper accommodation mechanism.

scholarly journals Superplastic Deformation Behavior of Rolled Mg-8Al-2Sn and Mg-8Al-1Sn-1Zn Alloys at High Temperatures

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1074 ◽  
Author(s):  
Shao-You Zhang ◽  
Cheng Wang ◽  
Long-Qing Zhao ◽  
Pin-Kui Ma ◽  
Jia-Wang Song ◽  
...  
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Superplastic Deformation ◽  
Elevated Temperatures ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Tensile Deformation ◽  
Tensile Elongation ◽  
Grain Boundary Sliding

The high-temperature superplastic deformation behavior of rolled Mg-8Al-2Sn (AT82) and Mg-8Al-1Sn-1Zn (ATZ811) alloys were investigated in this study. During tensile deformation at 573 K, no obvious grain growth occurred in both alloys, because of the high-volume fraction of second phases located at grain boundaries. Meanwhile, texture weakening was observed, suggesting that grain boundary sliding (GBS) is the dominant superplastic deformation mechanism, which agreed well with the strain rate sensitivity (m) and the activation energy (Q) calculations. The microstructural evolution during tensile deformation manifested that there were more and larger cavities in AT82 than ATZ811 during high-temperature tensile deformation. Therefore, superior superplasticity was found in the ATZ811 alloy that presented a tensile elongation of ~510% under a strain rate of 10−3 s−1 at 573 K, in contrast to the relatively inferior elongation of ~380% for the AT82 alloy. Meanwhile, good tensile properties at ambient temperature were also obtained in ATZ811 alloy, showing the ultimate tensile strength (UTS) of ~355 MPa, yield strength (YS) of ~250 MPa and elongation of ~18%. Excellent mechanical performance at both ambient and elevated temperatures can be realized by using economical elements and conventional rolling process, which is desirable for the industrial application of Mg alloy sheets.

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