Microstructure Evolution and Processing Map of Superalloy GH720Li during Isothermal Compression

2013 ◽  
Vol 747-748 ◽  
pp. 588-593
Author(s):  
Zhao Li ◽  
Shu Hong Fu ◽  
Tao Wang ◽  
Yu Xin Zhao ◽  
Yong Zhang ◽  
...  
Keyword(s):  
Microstructure Evolution ◽  
Hot Deformation ◽  
Processing Map ◽  
Flow Instability ◽  
Plastic Instability ◽  
Instability Criterion ◽  
Compression Tests ◽  
Softening Mechanism ◽  
Deformation Parameters ◽  
Hot Processing Map

sothermal compression tests for superalloy GH720Li were conducted to investigate the effect of hot deformation parameters on microstructure evolution. The changing characteristics of flow stress during hot deformation were also studied. The flow instability area was calculated based on Prasad Plastic Instability Criterion and the hot processing map was obtained. The results showed that dynamic recrystallization was the main softening mechanism of GH720Li alloy during hot deformation. The peak and steady stress decreased significantly with an increase of test temperature and a decrease of the strain rate. Finally, three unstable areas have been found from the processing map.

scholarly journals The Effect of α-Al(MnCr)Si Dispersoids on Activation Energy and Workability of Al-Mg-Si-Cu Alloys during Hot Deformation

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Xiaoguo Wang ◽  
Jian Qin ◽  
Hiromi Nagaumi ◽  
Ruirui Wu ◽  
Qiushu Li
Keyword(s):  
Activation Energy ◽  
Aluminum Alloys ◽  
Constitutive Equation ◽  
Hot Deformation ◽  
Flow Instability ◽  
Void Formation ◽  
Activation Energies ◽  
Compression Tests ◽  
Softening Mechanism ◽  
Dynamic Softening

The hot deformation behaviors of homogenized direct-chill (DC) casting 6061 aluminum alloys and Mn/Cr-containing aluminum alloys denoted as WQ1 were studied systematically by uniaxial compression tests at various deformation temperatures and strain rates. Hot deformation behavior of WQ1 alloy was remarkably changed compared to that of 6061 alloy with the presence of α-Al(MnCr)Si dispersoids. The hyperbolic-sine constitutive equation was employed to determine the materials constants and activation energies of both studied alloys. The evolution of the activation energies of two alloys was investigated on a revised Sellars’ constitutive equation. The processing maps and activation energy maps of both alloys were also constructed to reveal deformation stable domains and optimize deformation parameters, respectively. Under the influence of α dispersoids, WQ1 alloy presented a higher activation energy, around 40 kJ/mol greater than 6061 alloy’s at the same deformation conditions. Dynamic recrystallization (DRX) is main dynamic softening mechanism in safe processing domain of 6061 alloy, while dynamic recovery (DRV) was main dynamic softening mechanism in WQ1 alloy due to pinning effect of α-Al(MnCr)Si dispersoids. α dispersoids can not only resist DRX but also increase power required for deformation of WQ1 alloy. The microstructure analysis revealed that the flow instability was attributed to the void formation and intermetallic cracking during hot deformation of both alloys.

Hot Deformation Studies of a Low Carbon Steel Containing V

2013 ◽  
Vol 554-557 ◽  
pp. 1224-1231 ◽  
Author(s):  
Cecilia Poletti ◽  
Martina Dikovits ◽  
Javier Ruete
Keyword(s):  
Strain Rate ◽  
Hot Deformation ◽  
Flow Instability ◽  
True Strain ◽  
Low Carbon Steel ◽  
Dynamic Effect ◽  
Rate Sensitivity ◽  
Low Carbon ◽  
Compression Tests ◽  
Deformation Parameters

Low alloyed steels produced by continuous casting are thermomechanically treated to achieve final high mechanical properties, meaning a good combination of strength and toughness. The hot deformation mechanisms of a micro-alloyed steel containing up to 0.1wt% of V is studied by means of hot compression tests using a Gleeble®3800 device. Austenitization of samples is carried out at 1150°C during 2 minutes followed by cooling to the deformation temperature at 1Ks-1in the range of 750 – 1150°C. The studied strain rate range is from 0.01 to 80 s-1and the total true strain achieved is of 0.7. In situ water quenching is applied after the deformation to freeze the microstructure and avoid any post dynamic effect. The Ar3temperature is determined by dilatometry experiments to be 725°C for the used cooling rate. The stress values obtained from the compression tests are evaluated at different strains to determine the strain rate sensitivity and flow instability maps and thus, to predict the formability of the material in the range of studied deformation parameters. These maps are correlated to the microstructure at specific deformation parameters.

scholarly journals The Investigation on Flow Behavior of Powder Metallurgy Ti-10V-2Fe-3Al Alloy Using the Prasad Stability Criterion

2019 ◽  
Vol 50 (11) ◽  
pp. 5314-5323 ◽  
Author(s):  
Krystian Zyguła ◽  
Marek Wojtaszek ◽  
Oleksandr Lypchanskyi ◽  
Tomasz Śleboda ◽  
Grzegorz Korpała ◽  
...  
Keyword(s):  
Powder Metallurgy ◽  
Power Dissipation ◽  
Hot Deformation ◽  
High Efficiency ◽  
Flow Instability ◽  
Flow Behavior ◽  
Material Model ◽  
Instability Criterion ◽  
Processing Maps ◽  
Compression Tests

Abstract The hot deformation behavior of Ti-10V-2Fe-3Al alloy obtained by the powder metallurgy (PM) method was investigated. Material for the research was produced by blending of elemental powders followed by uniaxial hot pressing. Thermomechanical tests of Ti-10V-2Fe-3Al compacts were carried out to determinate the stress-strain relationships at the temperature range of 800 °C to 1000 °C and strain rate between 0.01 and 10 s−1. Based on the dynamic material model (DMM) theory, processing maps at constant strain value were developed using data obtained from hot compression tests. The processing maps were elaborated for the final strain value, which was 0.9, and with flow instability criterion domains applied to it. Two critical regions associated with the flow behavior of the investigated material were revealed. Microstructural changes during hot deformation at various temperatures and strain rates were discussed. The correlation between calculated efficiency of power dissipation, flow instability criterion, and microstructure evolution was determined. The presence of defects was confirmed in regions predicted by the instability maps. The microstructure of the investigated alloy, corresponding to the high efficiency of power dissipation characterized by the occurrence of dynamic recrystallization (DRX) phenomena, was also shown. Additionally, average hardness values in relation to variable process parameters were designated. Based on the conducted studies and analysis, processing windows for Ti-10V-2Fe-3Al alloy compacts were proposed.

scholarly journals The Deformation Behavior, Microstructural Mechanism, and Process Optimization of PM/Wrought Dual Superalloys for Manufacturing the Dual-Property Turbine Disc

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1127 ◽  
Author(s):  
Baoyun Zhang ◽  
Xiaoming Liu ◽  
Hao Yang ◽  
Yongquan Ning
Keyword(s):  
Hot Deformation ◽  
Deformation Behavior ◽  
Processing Map ◽  
Flow Instability ◽  
Rapid Development ◽  
Instability Criterion ◽  
Aviation Industry ◽  
Dual Property ◽  
Turbine Disc ◽  
Microstructural Mechanism

With the rapid development of modern aviation industry, dual-property turbine disc with fine comprehensive performance plays an important role in raising the thrust-to-weight ratio of the aero-engine. For manufacturing dual-property turbine disc, the powder metallurgy superalloy (PM) with excellent creep resistance was chosen as rim material, and the wrought superalloy with fine equiaxed grains was chosen as bore material. Electron beam welding was carried out on the PM/wrought dual superalloys. Hot compression tests were conducted on the PM/Wrought dual superalloys at temperatures of 1020–1140 °C and strain rates of 0.001–1.0 s−1. Deformation behavior and microstructure evolution have been investigated to study the deformation and recrystallization mechanism during hot deformation process. The results showed that PM/Wrought dual superalloy presents the similar flow behavior to single alloys and flow stress decreases significantly with the increase of deformation temperature or the decrease of strain rate. The apparent activation energy of deformation at the strain of 0.2 was determined as being 780.07 kJ·mol−1. The constitutive equation was constructed for modeling the hot deformation of PM/Wrought dual superalloy. Meanwhile, the processing map approach was further adopted to optimize the manufacturing process for the dual-property turbine disc. Additionally, a new instability criterion was proposed: the “cliff” and “valley” in the power dissipation map are determined as sufficient conditions for flow instability. The optimum processing parameter for manufacturing the PM/Wrought dual-property turbine disc can be obtained to enhance the mechanical properties, based on the analysis of processing map technology and microstructural mechanism.

Hot Deformation Behavior during the Hot Compression of AZ31 Alloy

2010 ◽  
Vol 139-141 ◽  
pp. 545-548 ◽  
Author(s):  
Shu Li Sun ◽  
Min Gang Zhang ◽  
Wen Wu He ◽  
Jun Qi Zhou ◽  
Gang Sun
Keyword(s):  
Hot Deformation ◽  
Deformation Behavior ◽  
Flow Instability ◽  
Strain Curve ◽  
Az31 Alloy ◽  
Hot Compression ◽  
Instability Criterion ◽  
Compression Tests ◽  
Hot Deformation Behavior ◽  
Hollomon Parameter

The hot deformation behavior of as-cast AZ31 magnesium alloys have been investigated at 200~400°C and strain rates 0.001~1s-1 by means of hot compression tests on a Gleeble-1500D thermal-mechanical simulator. We have analyzed the flow stress-strain curve and presented the constitutive equation by calculating stress exponent, activation energy and Zemer-Hollomon parameter. Then, the processing map of AZ31 alloys has been developed based on the dynamic material model theories and Prasad instability criterion. The flow instability domain is observed at lower temperature and the larger power dissipation rate is emerging at 300~400°C. We have analyzed the corresponding deformation microstructures and it is characteristic of dynamic recrystallization. These results have shown that AZ31 alloy has good workability at 300~400°C and lower strain rate.

Hot working of SP-700 titanium alloy with lamellar α + β starting structure using a processing map

2020 ◽  
Vol 111 (4) ◽  
pp. 297-306
Author(s):  
Amir Hosein Sheikhali ◽  
Maryam Morakkabati
Keyword(s):  
Titanium Alloy ◽  
Strain Rate ◽  
Hot Deformation ◽  
Processing Map ◽  
Microstructural Analysis ◽  
Shear Bands ◽  
Alpha Phase ◽  
Strain Rates ◽  
Compression Tests ◽  
Temperature Range

Abstract In this study, hot deformation behavior of SP-700 titanium alloy was investigated by hot compression tests in the temperature range of 700-9508C and at strain rates of 0.001, 0.1, and 1 s-1. Final mechanical properties of the alloy (hot compressed at different strain rates and temperatures) were investigated using a shear punch testing method at room temperature. The flow curves of the alloy indicated that the yield point phenomenon occurs in the temperature range of 800- 9508C and strain rates of 0.1 and 1 s-1. The microstructural analysis showed that dynamic globularization of the lamellar α phase starts at 7008C and completes at 8008C. The alpha phase was completely eliminated from b matrix due to deformation- induced transformation at 8508C. The microstructure of specimens compressed at 8508C and strain rates of 0.001 and 0.1 s-1showed the serration of beta grain boundaries, whereas partial dynamic recrystallization caused a necklace structure by increasing strain rate up to 1 s-1. The specimen deformed at 7008C and strain rate of 1 s-1was located in the instability region and localized shear bands formed due to the low thermal conductivity of the alloy. The processing map of the alloy exhibited a peak efficiency domain of 54% in the temperature range of 780-8108C and strain rates of 0.001- 0.008 s-1. The hot deformation activation energy of the alloy in the α/β region (305.5 kJ mol-1) was higher than that in the single-phase β region (165.2 kJ mol-1) due to the dynamic globularization of the lamellar a phase.

scholarly journals A flow instability criterion for alloys during hot deformation

2019 ◽  
Vol 37 ◽  
pp. 319-326
Author(s):  
Peng Wang ◽  
Katharina Hogrefe ◽  
David Piot ◽  
Frank Montheillet ◽  
María Cecilia Poletti
Keyword(s):  
Hot Deformation ◽  
Flow Instability ◽  
Instability Criterion

High Temperature Deformation Mechanisms and Processing Map for Hot Working of Cast-Homogenized Mg-3Sn-2Ca Alloy

2010 ◽  
Vol 638-642 ◽  
pp. 3616-3621 ◽  
Author(s):  
K.P. Rao ◽  
Y.V.R.K. Prasad ◽  
Norbert Hort ◽  
Karl Ulrich Kainer
Keyword(s):  
Strain Rate ◽  
Processing Map ◽  
Volume Fraction ◽  
Flow Instability ◽  
Back Stress ◽  
Hot Working ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Strain Rates ◽  
Compression Tests

The hot working behavior of Mg-3Sn-2Ca alloy has been investigated in the temperature range 300–500 oC and strain rate range 0.0003–10 s-1, with a view to evaluate the mechanisms and optimum parameters of hot working. For this purpose, a processing map has been developed on the basis of the flow stress data obtained from compression tests. The stress-strain curves exhibited steady state behavior at strain rates lower than 0.01 s-1 and at temperatures higher than 350 oC and flow softening occurred at higher strain rates. The processing map exhibited two dynamic recrystallization domains in the temperature and strain rate ranges: (1) 300–420 oC and 0.0003–0.003 s-1, and (2) 420–500 oC and 0.003–1.0 s-1, the latter one being useful for commercial hot working. Kinetic analysis yielded apparent activation energy values of 161 and 175 kJ/mole in domains (1) and (2) respectively. These values are higher than that for self-diffusion in magnesium suggesting that the large volume fraction of intermetallic particles CaMgSn present in the matrix generates considerable back stress. The processing map reveals a wide regime of flow instability which gets reduced with increase in temperature or decrease in strain rate.

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