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.

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.

The Effect of Controlled Melt-Solidification on the Strain Rate Sensitivity of a Squeeze-Cast Hybrid-Reinforced Aluminum AA 6061 Matrix Composite

2015 ◽  
Vol 16 ◽  
pp. 1-16
Author(s):  
B.O. Malomo ◽  
O.O. Fadodun ◽  
K.M. Oluwasegun ◽  
A.T. Ogunbodede ◽  
S.A. Ibitoye ◽  
...  
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Matrix Composite ◽  
Deformation Behavior ◽  
Squeeze Casting ◽  
Volume Fraction ◽  
Tensile Elongation ◽  
Testing Machine ◽  
Rate Sensitivity ◽  
Cooling Rates

A framework based on the relationship between variations in cooling rates and volume fraction of reinforcements during solidification processing to enhance the deformation behavior of aluminum alloy AA6061 matrix composite produced with a hybrid system of reinforcements is investigated in this study. The aluminum matrix composite with 5 %, 10 % and 20 % volume fraction of reinforcements (Al2O3-SiC) was synthesized by infiltrating molten aluminum AA 6061 at a pouring temperature of 740 °C into prefabricated preforms of reinforcements at a pressure of 80 MPa, die preheat temperature of 300 °C and pressure holding time of 15 s using the squeeze casting method. By employing water jet spraying at the rate of 0.1, 0.2 and 0.3 kg/s and taking measurements using a K-type thermocouple, cooling rates were obtained in correspondence with varying volume fractions of reinforcements. The developed composites were sectioned and microstructural features were examined by optical microscopy. Tensile testing was conducted according to ASTM B557 standard using an MTS testing machine. It was observed that cooling rates decreased as the volume fraction of reinforcements was increased and the cooling time also increased accordingly during this process. With respect to deformation behavior, higher cooling rates are associated with an improvement in mechanical properties at 5 % and 10 % additions of hybrid reinforcement particles but this effect diminishes as the volume fraction of reinforcements was increased to 20 %. Also, the strain rate sensitivity (SRS) exponent increased considerably with strain rates and volume fraction of reinforcements, but the tensile elongation values decreased with increasing volume fraction of reinforcements; and the variations in these properties were most significant for samples containing 20% volume fraction of hybrid reinforcements.From the foregoing, it follows that an experimentally-determined optimal solidification range is critical to the enhancement of deformation parameters as the volume fraction of reinforcements is varied in a squeeze casting process.

High-Temperature-Tensile-Deformation Behavior of Ti-6Al-4V Alloy with the Acicular α′ Martensite Microstructure

2016 ◽  
Vol 838-839 ◽  
pp. 243-248 ◽  
Author(s):  
Takuro Nishihara ◽  
Hiroaki Matsumoto ◽  
Yohei Iwagaki ◽  
Tohru Shiraishi ◽  
Yoshiki Ono
Keyword(s):  
High Temperature ◽  
Deformation Behavior ◽  
Tensile Deformation ◽  
Tensile Elongation ◽  
Rate Sensitivity ◽  
Specific Strength ◽  
High Specific Strength ◽  
Tensile Deformation Behavior ◽  
High Temperature Tensile ◽  
Martensite Microstructure

Titanium alloys are widely used in aerospace components, with the most widely used alloy being (α+β)-type Ti-6Al-4V (hereafter designated as Ti-64) alloy owing to its high specific strength and high formability associated with superplasticity. This work examines the tensile deformation behavior of the Ti-64 alloy with the acicular α′ martensite microstructure tested at from 700°C to 900°C. Higher tensile-elongation and higher strain-rate-sensitivity value are seen in the Ti-64 alloy with the α′ martensite microstructure as compared to that with the lamellar (α+β) microstructure. During deformation of the α′ martensite microstructure at 700°C or 800°C, acicular microstructure evolves into fine equiaxed (α+β) structure, whereas there is no apparent change in microstructure in the case of the lamellar (α+β) starting microstructure. This result indicates that dynamic globularization during deformation is strongly enhanced in the acicular α′ martensite starting microstructure, thereby leading to higher tensile elongation.

scholarly journals High Temperature Deformation Behavior of In-Situ Synthesized Titanium-Based Composite Reinforced with Ultra-Fine TiB Whiskers

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1863 ◽  
Author(s):  
Rongjun Xu ◽  
Bin Liu ◽  
Yong Liu ◽  
Yuankui Cao ◽  
Wenmin Guo ◽  
...  
Keyword(s):  
High Temperature ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Failure Modes ◽  
Grain Boundary Sliding ◽  
Coarse Grained ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Powder Metallurgy Method ◽  
Matrix Microstructure

A TiB/Ti-6Al-4V composite reinforced with ultra-fine TiB whiskers (UF-TiB) was prepared by the powder metallurgy method. High temperature compression tests were carried out to study the hot deformation behavior of the UF-TiB/Ti-6Al-4V composite. The compressive deformation was performed in the temperature range of 900–1200 °C and the strain rate range of 0.001–10 s−1. The results showed that stable flow occurred at the condition of 900–1200 °C/0.001–0.01 s−1. The optimum working condition was 900 °C/0.001 s−1, with the deformation mechanism of dynamic recrystallization (DRX). Instable flow occurred when the strain rate was higher than 0.01 s−1, where the failure modes included adiabatic shear deformation, whisker breakage and whisker/matrix debonding. The deformability of the UF-TiB/Ti-6Al-4V composite was much better than the traditional casted and the pressed + sintered TiB/Ti-6Al-4V composites, which are typically reinforced with coarse-grained TiB whiskers. The high deformability was primarily attributed to the ultra-fine reinforcements, which could coordinate the deformation more effectively. In addition, a fine matrix microstructure also had a positive effect on deformability because the fine matrix microstructure could improve the grain boundary sliding.

Deformation Behavior of a Multiphase Fine-Grained Mo-Si-B Alloy

2011 ◽  
Vol 284-286 ◽  
pp. 544-549
Author(s):  
J.L. Yu ◽  
Z.K. Li ◽  
Xin Zheng ◽  
H. Li ◽  
D. H. Wang ◽  
...  
Keyword(s):  
Deformation Behavior ◽  
Elevated Temperatures ◽  
Size Range ◽  
Tensile Elongation ◽  
Grain Boundary Sliding ◽  
Intermetallic Phases ◽  
Fine Grained ◽  
Fine Microstructure ◽  
Boundary Sliding ◽  
Hot Pressing Sintering

Mo-9Si-8B-3Hf alloy consisting of a Mo solid solution and intermetallic phases Mo3Si and Mo5SiB2was fabricated by hot pressing sintering to yield a fine microstructure with all three phases being in the size range of micrometer. The tensile properties of this alloy at elevated temperature were evaluated in vacuum at elevated temperatures. This alloy displayed extensive plasticity or superplasticity at temperatures ranging from 1400 °C to 1560 °C with strain rate of 3×10-4s-1. The tensile elongation of 410% is measured at 1560 °C. Grain boundary sliding is the main mechanism of plastic deformation for this alloy.

High Strain Rate Deformation Behavior of Mg–Al–Zn Alloys at Elevated Temperatures

2007 ◽  
Vol 340-341 ◽  
pp. 107-112 ◽  
Author(s):  
Hiroyuki Watanabe ◽  
Koichi Ishikawa ◽  
Toshiji Mukai
Keyword(s):  
High Temperature ◽  
High Strain Rate ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Elevated Temperatures ◽  
High Strain ◽  
Strain Rate Range ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Rate Range

High temperature deformation behavior of AZ31 and AZ91 magnesium alloys was examined by compression tests over a wide strain rate range from 10–3 to 103 s–1 with emphasis on the behavior at high strain rates. The dominant deformation mechanism in the low strain rate range below 10–1 s–1 was suggested to be climb-controlled dislocation creep. On the other hand, experimental results indicated that the deformation at a high strain rate of ~103 s–1 proceeds by conventional plastic flow of dislocation glide and twinning even at elevated temperatures. The solid-solution strengthening was operative for high temperature deformation at ~103 s–1.

An Investigation on High Strain Rate Superplasticity of an Al-Cu-Mg-Ti-Sr Ingot Alloy

2004 ◽  
Vol 471-472 ◽  
pp. 692-696
Author(s):  
Xiao Jing Xu ◽  
Lan Cai ◽  
Seock Sam Kim
Keyword(s):  
High Strain Rate ◽  
Strain Rate ◽  
Superplastic Deformation ◽  
High Strain ◽  
Tensile Elongation ◽  
Rate Sensitivity ◽  
Hot Extrusion ◽  
Initial Strain Rate ◽  
Grain Boundary Sliding ◽  
Dislocation Slip

An ingot aluminum alloy (Al-Cu-Mg-Ti-Sr) with high strength and high strain rate superplasticity has been successfully developed through a conventional manufacture route consisting of casting, heat treatment, hot extrusion with a low extrusion rate of only 10:1, hot-rolling and further cold-rolling, which is cost effective and suitable for large volume production industries. The tensile test result showed the alloy possesses not only a high ultimate strength of 513.85MPa at room temperature, but also a good high strain rate superplasticity with the tensile elongation of 174~224%, the flow stress of 17.1~33.9MPa and the strain rate sensitivity m-value of 0.174~0.293 in the initial strain rate of 3.16×10-2~1.0×10-1s-1 and at the temperature of 748K~793K. Differential scanning calorimeter (DSC) analysis showed that the superplastic deformation has no relationship with liquid phase. Scanning electron microscopy (SEM) analysis of fracture surface and surface showed that the superplastic deformation results from fine grain boundary sliding and dislocation slip.

Effect of Hot Rolling Deformation on Superplastic Deformation Behavior of TiNP/2014Al Composite

2011 ◽  
Vol 264-265 ◽  
pp. 90-95
Author(s):  
Hui E Hu ◽  
Liang Zhen
Keyword(s):  
Strain Rate ◽  
Hot Rolling ◽  
Deformation Mechanism ◽  
Deformation Behavior ◽  
Superplastic Deformation ◽  
Grain Boundary Sliding ◽  
Composite Sheet ◽  
Boundary Sliding ◽  
Effect Of Hot Rolling ◽  
Rolling Deformation

1.5 mm, 0.7 mm and 0.3 mm thicknesses TiNP/2014Al composite sheets were obtained by hot rolling deformation carried out on as-extruded TiNP/2014Al composite rod. The effect of hot rolling deformation on high strain rate superplastic deformation behavior of the composite was researched by tensile experiment, OM, and SEM. Results show that 0.7mm thickness TiNP/2014Al composite sheet can gain the maximum elongation of 351% at 818 K and 3.3×10-1 s-1, and the m value is 0.43. The optimum strain rate increases with decreasing thickness of the TiNP/2014Al composite sheets. Flow stress and work hardening ability show contrary change tendency to optimum strain rate. The 0.7 mm thickness TiNP/2014Al composite sheet has medium flow resistance stress and shows excellent stability of plastic flow. Fracture surfaces show that the main superplastic deformation mechanism of the TiNP/2014Al composite includes in grain boundary sliding. Subgrain boundary sliding maybe another superplastic deformation mechanism.

scholarly journals Vacuum superplastic deformation behavior of a near-alpha titanium alloy TA32

2020 ◽  
Vol 321 ◽  
pp. 11018
Author(s):  
Chao Cheng ◽  
Weitang Zhang ◽  
Zhiyong Chen ◽  
Liang Jin ◽  
Qingjiang Wang
Keyword(s):  
Titanium Alloy ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Superplastic Deformation ◽  
Surface Oxidation ◽  
Superplastic Forming ◽  
Grain Boundary Sliding ◽  
Texture Intensity ◽  
Near Space ◽  
Alpha Titanium

TA32 is a heat-resistant titanium alloy developed for superplastic forming in fabrication of near-space supersonic aerocraft. Clarification of superplastic deformation behavior is important to the optimization of forming parameters. Superplastic tensile test was conducted in vacuum to eliminate the effect of surface oxidation on experimental data, the test temperature and strain rate varied from 900oC to 960oC and 5.32×10-4 to 2.08×10-2s-1, respectively. It was observed that the size of equiaxed α grains exhibited a trend of coarsening with the increase of temperature and decrease of strain rate. Textures of deformed specimens exhibited random distribution with a decreased texture intensity compared with the as-received materials. The superplastic deformation mechanism of TA32 alloy was dominated by grain boundary sliding, which is accommodated by grain rotation and dynamic recrystallization.

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