Investigation on the Grain Growth of Fe-40Ni-Ti Austenitic Steel in Heating Process

2014 ◽  
Vol 788 ◽  
pp. 272-276 ◽  
Author(s):  
Shao Qiang Yuan ◽  
Xiao Juan Zhang ◽  
Yue Hui Yang ◽  
Guo Li Liang
Keyword(s):  
Grain Growth ◽  
Room Temperature ◽  
Optical Microscope ◽  
Growth Behavior ◽  
Heating Process ◽  
Dislocation Configuration ◽  
Transmission Electron ◽  
The Matrix ◽  
Dislocation Cells ◽  
Grain Growth Behavior

Fe-40Ni alloy, keeping face-centred cubic structure (FCC) at room temperature, possesses similar stacking fault energy to that of austenite in steels at wide temperatures. The grain growth behavior of Fe-40Ni-Ti alloy at high temperatures was investigated by optical microscope and transmission electron microscopy (TEM). The results show that the grains grow very slowly from 880°C to 1160°C at holding time of 150min. At about 1220°C, the grain growing tendency can be clearly observed. At 1300°C, the rain size increases rapidly and coarsens when hold for 30min.TiN precipitates forms during the solidification and and strain induced precipitates can dissolve into the matrix, resulting in the grain boundaries moving easily. The evolution of dislocation configuration is retarded by the strain induced precipitates, which enhances the stabilization of dislocation cells.

Grain Boundary Segregation-Induced Phase Transformation and Grain Growth in Y2O3-Stabilized ZrO2 Polycrystals

2014 ◽  
Vol 616 ◽  
pp. 8-13
Author(s):  
Koji Matsui ◽  
Hidehiro Yoshida ◽  
Yuichi Ikuhara
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Boundary Segregation ◽  
Growth Behavior ◽  
Grain Boundary Segregation ◽  
Transmission Electron ◽  
Grain Growth Behavior

We systematically investigated the phase transformation and grain-growth behaviors during sintering in 2 and 3 mol% Y2O3-stabilized tetragonal ZrO2 (2Y and 3Y) and 8 mol% Y2O3-stabilized cubic ZrO2 polycrystals (8Y). In particular, grain-boundary segregation and grain-interior distribution of Y3+ ions were examined by high-resolution transmission electron microscopy (HRTEM)- and scanning transmission electron microscopy (STEM)-nanoprobe X-ray energy dispersive spectroscopy (EDS) techniques. Above 1200°C, grain growth during sintering in 8Y was much faster than that in 2Y and 3Y. In the grain boundaries in these specimens, amorphous layers did not present; however, Y3+ ions segregated at the grain boundaries over a width of about 10 nm. The amount of segregated Y3+ ions in 8Y was significantly less than in 2Y and 3Y. This indicates that the amount of segregated Y3+ ions is related to grain growth behavior; i.e., an increase in segregated Y3+ ions retards grain growth. Therefore, grain-growth behavior during sintering can be reasonably explained by the solute-drag mechanism of Y3+ ions segregating along the grain boundary. In 2Y and 3Y, the cubic-phase regions were formed in grain interiors adjacent to the grain boundaries and/or the multiple junctions in which Y3+ ions segregated, which can be explained by a grain boundary segregation-induced phase transformation (GBSIPT) mechanism.

VSR Mechanism Based on MC Algorithm Simulation of Grain Growth Behavior of Sustainable Materials

2013 ◽  
Vol 340 ◽  
pp. 392-395 ◽  
Author(s):  
Xi Zou ◽  
Xue Jun Li ◽  
Yong Yi Gao ◽  
Kuan Fang He ◽  
Jian Jian Kun
Keyword(s):  
Electron Microscopy ◽  
Residual Stress ◽  
Grain Growth ◽  
Stress Relief ◽  
Growth Behavior ◽  
Dislocation Configuration ◽  
Simulation Results ◽  
Sustainable Materials ◽  
Grain Growth Behavior ◽  
Matlab Programming

Established a dynamic model of recrystallization dislocation, proposed MC algorithm simulation describing grain growth behaviors that can explain VSR eliminate component residual stress mechanism from the micro, which can provide an intuitive visualization. Used MATLAB programming grain growth of the grain in the different MC steps simulate images, to discuss the grain size distribution and the energy change in different MC steps, while compared the simulation results with the existing sample dislocation configuration electron microscopy photos around the VSR. It reflects the same trend, which can show that the MC method in numerical simulation of grain growth can fully reflect component microstructure evolution around VSR. Micro explains the VSR mechanism of residual stress relief member which provides intuitive visual basis.

Effect of Nb and V on Austenite Grain Growth Behavior of the Cr-Mo-V Steel for Brake Discs

2018 ◽  
Vol 37 (9-10) ◽  
pp. 899-907
Author(s):  
Dan Wu ◽  
Fuming Wang ◽  
Jin Cheng ◽  
Changrong Li
Keyword(s):  
Grain Growth ◽  
Bearing Steel ◽  
Growth Behavior ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Transmission Electron ◽  
Brake Discs ◽  
Rapid Dissolution ◽  
Grain Growth Behavior ◽  
Austenite Grain Growth

AbstractIn order to improve the performance of the steel for brake discs, including strength, toughness and thermal fatigue resistance, Nb and V are added to the steel. The effect of Nb and V on austenite grain growth behavior of the Cr-Mo-V steel for brake discs was studied by analyzing the phase equilibria as well as the microstructures. The precipitation behaviors of precipitates were also investigated based on transmission electron microscopy and energy-dispersive spectroscopy. The results showed that V-rich M8C7 and NbC particles existed at the experimental temperatures. The abnormal grain growth in Nb-free steels was affected by the partial dissolution and coarsening of M8C7 particles. With increasing V content, the grains were refined, but the mixed grain phenomenon became more serious. There were many small NbC particles in Nb-bearing steel, so the grains were effectively refined. Furthermore, a prediction model, which calculates the austenite grain size considering precipitate pinning effect, was established, and the model was well consistent with the actual situation in the Nb-bearing steel up to 1,100 °C. The grains of the Nb-free steels were sensitive to the increments of temperature and time due to the rapid dissolution or coarsening of M8C7 particles.

Rapid Grain Growth of Hot Extruded Al-Zn-Mg-Cu-(Sc) Alloy during Heat Treatment

2004 ◽  
Vol 449-452 ◽  
pp. 605-608
Author(s):  
Dong Woo Suh ◽  
Sang Yong Lee ◽  
Jun Yun Kang ◽  
Kyu Hwan Oh
Keyword(s):  
Heat Treatment ◽  
Grain Growth ◽  
Artificial Aging ◽  
Surface Region ◽  
Optical Microscope ◽  
Growth Behavior ◽  
Alloying Element ◽  
Solution Treated ◽  
Grain Growth Behavior ◽  
Electron Back Scattered Diffraction

Rapid grain growth and artificial aging characteristics during heat treatment is investigated for hot extruded Al-Zn-Mg-Cu-(Sc) alloys. Two Al-0.1wt%Sc alloys with different alloying element content are hot extruded to make T-shape bars at 380°C, and then the bars are solution treated for 2 hours at 480oC followed by artificial aging for 24 hours at 120°C. Microstructural evolution of the hot extruded bar is analyzed with optical microscope and electron back scattered diffraction (EBSD) mapping. Two kind of extruded bar shows different grain growth behavior at surface region and different artificial aging characteristics. The interaction between the precipitates and the grain growth during the heat treatment is thought to be responsible for the different grain growth behavior.

The Effect of Grain Size on Superplastic Deformation of Ti-6Al-4V Alloy

2007 ◽  
Vol 551-552 ◽  
pp. 387-392 ◽  
Author(s):  
Wen Juan Zhao ◽  
Hua Ding ◽  
D. Song ◽  
F.R. Cao ◽  
Hong Liang Hou
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Superplastic Deformation ◽  
Initial Strain Rate ◽  
Deformation Mode ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Coarse Grained ◽  
Transmission Electron ◽  
Grain Growth Model

In this study, superplastic tensile tests were carried out for Ti-6Al-4V alloy using different initial grain sizes (2.6 μm, 6.5μm and 16.2 μm) at a temperature of 920°C with an initial strain rate of 1×10-3 s-1. To get an insight into the effect of grain size on the superplastic deformation mechanisms, the microstructures of deformed alloy were investigated by using an optical microscope and transmission electron microscope (TEM). The results indicate that there is dramatic difference in the superplastic deformation mode of fine and coarse grained Ti-6Al-4V alloy. Meanwhile, grain growth induced by superplastic deformation has also been clearly observed during deformation process, and the grain growth model including the static and strain induced part during superplastic deformation was utilized to analyze the data of Ti-6Al-4V alloy.

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