Investigation of Compression Deformation Behavior and Microstructure Evolution of NiAl-Cr (Mo)-Hf Alloy at Elevated Temperature

2007 ◽  
Vol 551-552 ◽  
pp. 457-461
Author(s):  
Guo Qing Chen ◽  
S.H. Ji ◽  
Wen Long Zhou ◽  
C.W. Wu ◽  
Jian Ting Guo ◽  
...  
Keyword(s):  
Elevated Temperature ◽  
Flow Stress ◽  
Microstructure Evolution ◽  
Deformation Behavior ◽  
Initial Strain Rate ◽  
Deformation Degree ◽  
Maximum Deformation ◽  
Maximum Value ◽  
Compression Deformation ◽  
Nial Matrix

NiAl-based alloy is a promising material applied in the fields of aeronautic and astronautic instruments. In the paper the compression deformation behavior and microstructure evolution of NiAl-Cr(Mo)-Hf alloy at elevated temperature were studied. The results demonstrate that the alloy behaves good formability in the temperature ranging from 1320°C to 1360°C, in which the maximum initial strain rate is about 8.3×10-4s-1 and the maximum deformation resistance is lower than 40MPa. During compression at temperature between 1250°C and 1300°C the flow stress increased sharply with the increasing of the deformation degree. When compression deformation at 1320°C~1360°C, the flow stress decreased obviously and the flow stress decreased slightly after reached the maximum value. By analyzing the microstructure evolution during compression it can be concluded that as-casting microstructure was improved in deformation. The grains were refined and the brittle phases of lamellar Cr(Mo) existing at NiAl matrix were broken. The porosities in as-casting material were eliminated during compression and the density of the material increased. The fracture toughness of the alloy increased from 6.4MPa·m1/2 to 9.8MPa·m1/2 after compression.

Investigation of Deformation Behavior of SS304 and Pure Copper Subjected to Electrically Assisted Forming Process

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Tianhao Jiang ◽  
Linfa Peng ◽  
Peiyun Yi ◽  
Xinmin Lai
Keyword(s):  
Elevated Temperature ◽  
Flow Stress ◽  
Constitutive Model ◽  
Electric Current ◽  
Deformation Behavior ◽  
Pure Copper ◽  
Annihilation Process ◽  
Forming Process ◽  
Electrically Assisted ◽  
Dislocation Movement

Both electrically assisted tension (EAT) and thermally assisted tension (TAT) tests were performed on SS304 and pure copper to decouple the influence of elevated temperature from electric current on flow stress and ductility. It is found that the reduction on flow stress and ductility of SS304 are more dependent on the elevated temperature than electric current, but electric current has a stronger effect by 10% on reducing flow stress and ductility of pure copper than the elevated temperature does. As the flow stress and ductility of two metals are related to the dislocation evolution, a constitutive model considering both storage and annihilation process of dislocation was established to describe the effect of electric current and temperature on dislocation movement. It is found that electric current accelerated the annihilation process of dislocation in pure copper up to 20% in EAT compared with that in TAT, but such phenomenon was rarely observed in SS304. Furthermore, attempts have also been made to distinguish the influence of elevated temperature with that of electric current on microstructure evolution and it is also found that the formation of [111] crystals in pure copper is nearly 10% less in EAT than that in TAT.

Establishment of Flow Stress Model of EW75 Alloy

2013 ◽  
Vol 423-426 ◽  
pp. 241-246
Author(s):  
Ming Long Ma ◽  
Kui Zhang
Keyword(s):  
Mathematical Model ◽  
Flow Stress ◽  
Magnesium Alloy ◽  
Strain Rate ◽  
Strain Rate Range ◽  
Strain Rates ◽  
Stress Strain ◽  
Deformation Degree ◽  
Maximum Deformation ◽  
The Mathematical Model

The behavior evolvement of Mg-7.22Gd-4.84Y-1.26Nd-0.58Zr (EW75) magnesium alloy during the hot deformation process was discussed. The flow stress behavior of magnesium alloy over the strain rate range 0.002s-1to 2s-1and the temperature range 623K to 773K had been researched on Gleeble-1500D hot simulator under the maximum deformation degree 60%. A mathematical model was established to predict the stress-strain curves of this alloy during deformation. The experimental results showed that the stress-strain curves were obviously affected by the strain rates and deformation temperatures. The mathematical model could predict the stress-strain curves when the strain rates were under 0.2-1, but there was significant error in some of stress-strain curves when the strain-rate was 2-1by the reason of deformation temperature rising.

scholarly journals Microstructure and Hot Deformation Behavior of the Mg–8 wt.% Sn–1.5 wt.% Al Alloy

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2050
Author(s):  
Zhaoqian Sun ◽  
Yongjun Li ◽  
Kui Zhang ◽  
Xinggang Li ◽  
Minglong Ma ◽  
...  
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Secondary Phase ◽  
Al Alloy ◽  
Hot Deformation Behavior ◽  
Deformation Degree ◽  
Maximum Deformation ◽  
Textural Evolution ◽  
Deformation Properties

Mg–Sn–Al alloy is a new type of heat-resistant magnesium alloy with great potential and the hot deformation process of this alloy is of great significance for its application. The microstructure, hot deformation behavior, textural evolution, and processing map of a Mg–8 wt.% Sn–1.5 wt.% Al alloy were studied. A Gleeble 1500 D thermo-mechanical simulator was used. The temperature of deformation was 653 to 773 K, the strain rate was 0.001–1 s−1, and the maximum deformation degree was 60%. The obtained results show that the rheological stress of the alloy decreases with an increase in deformation temperature and increases with an increase in the strain rate. The alloy is completely dynamically recrystallized at 653 K, and the entire structure is formed of homogeneous crystals/grains, with small secondary phase particles distributed at the crystal boundary. The mean apparent activation energy of hot compression deformation is 153.5 kJ/mol. The Mg–8 wt.% Sn–1.5 wt.% Al alloy exhibits excellent plastic deformation properties, an expansive thermal processing interval, and a narrow instability zone under the test temperature and deformation rate. The optimal process parameters of the alloy comprise deformation temperatures between 603 and 633 K and strain rates of 0.03 to 0.005 s−1.

Deformation Behavior of AZ31 Magnesium Alloy at Elevated Temperature

2013 ◽  
Vol 652-654 ◽  
pp. 1976-1979
Author(s):  
Ya Lin Lu ◽  
Xing Cheng Li ◽  
Hong Jin Wang ◽  
Xiao Ping Li
Keyword(s):  
Elevated Temperature ◽  
Flow Stress ◽  
Magnesium Alloy ◽  
Process Parameters ◽  
Deformation Behavior ◽  
Deformation Process ◽  
Strain Rates ◽  
Hot Compression Test ◽  
Dynamic Recrystallisation ◽  
Gleeble 3500

Hot compression test for AZ3l magnesium alloy at deformation temperatures of 523-723K and strain rates of 0.01-10s-1 were carried out using Gleeble-3500 thermo-mechanical simulator. The experimental results show that the flow stress and microstructure vary apparently with deformation process parameters. Microstructure observations show that dynamic recrystallisation (DRX) takes place during the deformation. The characteristic with the dynamic recrystallization change with the process parameters.

scholarly journals Analysis of Deformation Behavior and Microstructure Changes for α/β Titanium Alloy at Elevated Temperature

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 303
Author(s):  
Wenhua Yang ◽  
Wei Ji ◽  
Zhaohui Zhou ◽  
Aiguo Hao ◽  
Linxin Qing ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Flow Stress ◽  
Strain Rate ◽  
Microstructure Evolution ◽  
Deformation Behavior ◽  
Deformation Temperature ◽  
Phase Region ◽  
Heating Effect ◽  
Microstructure Changes ◽  
Transus Temperature

In this paper, the isothermal compressive behavior of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si titanium alloy was investigated on a Gleeble-3500 simulator in the temperature range from 1073 to 1373 K at an interval of 50 K (while the phase transus temperature is approximately 1273 K) and the strain rate range of 0.001–10 s−1. Microstructure evolution and deformation behavior were investigated. The typical flow softening behavior during deformation is observed, which can be explained by the deformation heating effect and microstructure changes. The deformation heating effect is influenced by strain rate and deformation temperature, and it increases with the increasing strain rate and decreasing deformation temperature. In the α + β phase field, the fractions of the primary α phase decrease with the increase of deformation temperature and strain rate. In this case, dynamic recovery may be the main mechanism for microstructure evolution based on the electron back-scatter diffraction (EBSD) analysis. The fully phase transformation occurs above the β transus temperature, which is governed by Burgers orientation relations. The Zener–Hollomon parameter with an exponent-type equation was used to intuitively describe the effects of the deformation temperatures and strain rates on the flow stress behaviors. Furthermore, the influence of strain was incorporated in the constitutive analysis. A fourth-order polynomial was ideally matched to represent the influence of strain. In consequence, the constitutive equation of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si titanium alloy including the phase transus and compensation of the strain was developed based on the experimental results throughout the deformation process. The results indicated that the correlation coefficient (R), root mean square error (RMSE), and the average absolute relative error (AARE) were calculated to be 0.987, 3.585 MPa, and 9.62% in the single-phase region and 0.979, 18.78 MPa, and 9.16% in the duplex-phase region, respectively. Hence, the constitutive model proposed in this research can provide accurate and precise theoretical prediction for the flow stress behavior of Ti-6.5Al-3.5Mo-1.5Zr-0.3Si titanium alloy.

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