scholarly journals Constitutive Model and Microstructure Evolution Finite Element Simulation of Multidirectional Forging for GH4169 Superalloy

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1695
Author(s):  
Yongbo Jin ◽  
Chenyang Xi ◽  
Peng Xue ◽  
Chunxiang Zhang ◽  
Sirui Wang ◽  
...  
Keyword(s):  
Grain Size ◽  
Microstructure Evolution ◽  
Parameter Selection ◽  
Compression Rate ◽  
Multidirectional Forging ◽  
Fine Grain ◽  
Suitable Parameter ◽  
Element Simulation ◽  
Gh4169 Superalloy ◽  
Recrystallized Grain Size

This study investigates three processes of multidirectional forging (MDF), namely, closed MDF (CMDF), single-open MDF, and double-open MDF, by using a constitutive equation and a dynamic recrystallization model of hot deformation of the GH4169 superalloy. The microstructure evolution of the three processes is simulated and compared. Among the three processes, the double-open MDF obtains the highest recrystallization degree, followed by the CMDF and the single-open MDF under the same reduction. The recrystallization degree of CMDF reaches 99.5% at 1000 °C and 9 passes, and the average recrystallized grain size is small, which is approximately 8.1 μm. The double-open MDF can obtain a fine grain size of forgings at 9 passes and 1000 °C, and it is easy to obtain forgings with the single-open MDF with uniform performance. The temperature is 850 °C–1000 °C, the compression rate is 0.15–0.2, and the pass is 5–9, which are the suitable parameter selection ranges for the CMDF. The temperature is 950 °C–1000 °C, the compression rate is 0.1–0.2, and the pass is 7–9, which are the suitable parameter selection ranges for single-open MDF. The temperature is 850 °C–1000 °C, the compression rate is 0.1–0.2, and the pass is 6–9, which are the suitable parameter selection ranges for the double-open MDF.

scholarly journals Constitutive Equation of GH4169 Superalloy and Microstructure Evolution Simulation of Double-Open Multidirectional Forging

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1146 ◽  
Author(s):  
Jin ◽  
Xue ◽  
Yang ◽  
Zhang ◽  
Zhang ◽  
...  
Keyword(s):  
Grain Size ◽  
Constitutive Equation ◽  
Microstructure Evolution ◽  
Volume Fraction ◽  
Simulation Software ◽  
Maximum Temperature ◽  
Thermal Compression ◽  
Multidirectional Forging ◽  
Gh4169 Superalloy ◽  
Recrystallized Grain Size

This paper presented a double-open multidirectional forging with relatively few deformation passes and a uniform deformation. The constitutive equation and dynamic recrystallization model of the GH4169 superalloy were identified based on a thermal compression test and imported into Deform simulation software. The microstructure evolution law of GH4169 superalloy undergoing double-open multidirectional forging was simulated. The evolution of the recrystallization volume fraction and recrystallized grain size of the GH4169 superalloy during double-open multidirectional forging was obtained. Both higher temperatures and more passes were found to produce more complete recrystallization and smaller recrystallization grain size. At the maximum temperature studied, 1000 °C, with nine passes, the recrystallization volume fraction exceeded 95%, and the recrystallized grain size reached 3–5.5 µm.

scholarly journals Study on Microstructure Evolution and Mechanical Properties of Ti2AlNb-Based Alloy under Canning Compression and Annealing

Metals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 980 ◽  
Author(s):  
Wang ◽  
Xu ◽  
Sun ◽  
Zong ◽  
Chen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Microstructure Evolution ◽  
Texture Evolution ◽  
Annealing Treatment ◽  
Deformation Degree ◽  
Height Reduction ◽  
Schmid Factor ◽  
B2 Phase ◽  
Recrystallized Grain Size

The influence of height reduction on the microstructure evolution and mechanical properties of the Ti2AlNb-based alloy was investigated during canning compression and subsequent annealing. After the annealing treatment, the spheroidized B2 phase grains occurred because of partial recrystallization. Meanwhile, the texture evolution of the B2 phase and O phase were analyzed under the deformation degree, ranging from 25% to 75%. The results show that the mechanical properties of the post-annealed alloys were co-affected by the grain size and Schmid factor of the B2 phase. When the height reduction was less than 25%, the compression strength was mainly affected by the grain size. When the height reduction was higher than 50%, it was mainly dominated by the Schmid factor. When the deformation degree reached 75%, the recrystallized grain size decreased to 0.9 μm. Meanwhile, the Schmid factor of a {110}<001> slip system in B2 phase reduced to 0.34. Therefore, the yield strength of the Ti2AlNb alloy at room temperature increased from 892 MPa in the as-rolled condition to 935 MPa after the canning compression and annealing.

Effect of Deformation Parameters on Microstructure Evolution of Hot Deformed Superalloy GH4169

2015 ◽  
Vol 744-746 ◽  
pp. 1382-1385
Author(s):  
Tong He ◽  
Jing Hong Tuo ◽  
Zhi Hua Li ◽  
Qing An Tai
Keyword(s):  
Grain Size ◽  
Strain Rate ◽  
Microstructure Evolution ◽  
Temperature Increase ◽  
Compression Tests ◽  
Rate Decrease ◽  
Microstructural Parameters ◽  
Nickel Based Superalloy ◽  
Deformation Parameters ◽  
Recrystallized Grain Size

The evolution of the microstructure of a typical nickel-based superalloy GH4169 is investigated by the hot compression tests. The microstructural parameters such as fraction of recrystallization and grain size were analysed quantitatively. The results show that the effects of deforming temperature and strain rate on the dynamic recrystallized grain size are significant. With the deformed temperature increase and the strain rate decrease, the dynamic recrystallized grain size increases.

A Mesoscopic Modelling Framework of Microstructure Evolution and its Application on Thermo-Mechanical Processes

2021 ◽  
Vol 1035 ◽  
pp. 792-800
Author(s):  
Na Min Xiao ◽  
Ai Xue Sha ◽  
Xing Wu Li
Keyword(s):  
Grain Size ◽  
Microstructure Evolution ◽  
Solid Phase ◽  
Field Method ◽  
Phase Field Method ◽  
Thermomechanical Process ◽  
Modelling Framework ◽  
Mesoscopic Modelling ◽  
The Matrix ◽  
Recrystallized Grain Size

In present study a quantitative modelling framework based on phase-field method is developed to simulate the microstructure evolution during thermomechanical process, e. g. grain growth, recrystallization, solid phase transformations and their interactions. Two application cases of microstructure evolution are introduced. The first one is the dynamic recrystallization behavior during the hot deformation of stainless steel. The effect of thermo-mechanical parameters including strain, strain rate, and temperature on DRX have been investigated quantitatively. Moreover, the present simulation provided an explanation of the dependence of final recrystallized grain size on initial grain size when it is decreased to a critically small value. This modelling framework is also used to simulate the interaction between the dissolution of precipitates and grain coarsening of matrix in the nickel alloys. The simulation results show that the decreasing dissolution temperature of precipitate slow down the matrix coarsening kinetics obviously. This provides an quantitative tool to predict and control the local microstructure of nickel alloy disk. In summary, the mesoscopic modelling can be used to investigate more kinetic details of microstructure evolution and engineering optimization for thermo-mechanical process.

Aspects of microanalysis in a transmission electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 510-511
Author(s):  
R. Sinclair ◽  
B.E. Jacobson
Keyword(s):  
Grain Size ◽  
Electron Beam ◽  
Electron Microscope ◽  
Chemical Analysis ◽  
Transmission Electron Microscope ◽  
Vapor Deposition ◽  
Critical Currents ◽  
X Ray ◽  
Fine Grain ◽  
Transmission Electron

INTRODUCTIONThe prospect of performing chemical analysis of thin specimens at any desired level of resolution is particularly appealing to the materials scientist. Commercial TEM-based systems are now available which virtually provide this capability. The purpose of this contribution is to illustrate its application to problems which would have been intractable until recently, pointing out some current limitations.X-RAY ANALYSISIn an attempt to fabricate superconducting materials with high critical currents and temperature, thin Nb3Sn films have been prepared by electron beam vapor deposition [1]. Fine-grain size material is desirable which may be achieved by codeposition with small amounts of Al2O3 . Figure 1 shows the STEM microstructure, with large (∽ 200 Å dia) voids present at the grain boundaries. Higher quality TEM micrographs (e.g. fig. 2) reveal the presence of small voids within the grains which are absent in pure Nb3Sn prepared under identical conditions. The X-ray spectrum from large (∽ lμ dia) or small (∽100 Ǻ dia) areas within the grains indicates only small amounts of A1 (fig.3).

scholarly journals Effect of Strain-Induced Precipitation on the Recrystallization Kinetics in a Model Alloy

2021 ◽  
Author(s):  
Mo Ji ◽  
Martin Strangwood ◽  
Claire Davis
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Avrami Exponent ◽  
Model Alloy ◽  
Size Distributions ◽  
Recrystallization Kinetics ◽  
Grain Size Distributions ◽  
Recrystallized Grain Size ◽  
Nb Addition

AbstractThe effects of Nb addition on the recrystallization kinetics and the recrystallized grain size distribution after cold deformation were investigated by using Fe-30Ni and Fe-30Ni-0.044 wt pct Nb steel with comparable starting grain size distributions. The samples were deformed to 0.3 strain at room temperature followed by annealing at 950 °C to 850 °C for various times; the microstructural evolution and the grain size distribution of non- and fully recrystallized samples were characterized, along with the strain-induced precipitates (SIPs) and their size and volume fraction evolution. It was found that Nb addition has little effect on recrystallized grain size distribution, whereas Nb precipitation kinetics (SIP size and number density) affects the recrystallization Avrami exponent depending on the annealing temperature. Faster precipitation coarsening rates at high temperature (950 °C to 900 °C) led to slower recrystallization kinetics but no change on Avrami exponent, despite precipitation occurring before recrystallization. Whereas a slower precipitation coarsening rate at 850 °C gave fine-sized strain-induced precipitates that were effective in reducing the recrystallization Avrami exponent after 50 pct of recrystallization. Both solute drag and precipitation pinning effects have been added onto the JMAK model to account the effect of Nb content on recrystallization Avrami exponent for samples with large grain size distributions.

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