scholarly journals In Situ Investigation of Grain Evolution of 300M Steel in Isothermal Holding Process

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1862 ◽  
Author(s):  
Rongchuang Chen ◽  
Zhizhen Zheng ◽  
Jianjun Li ◽  
Ning Li ◽  
Fei Feng
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Isothermal Holding ◽  
In Situ Observation ◽  
Initial Stage ◽  
300M Steel ◽  
Average Grain Size ◽  
In Situ Observations

The relationships between initial microstructures, process parameters, and grain evolutions in isothermal holdings have drawn wide attention in recent years, but the grain growth behaviors of 300M steel were not well understood, resulting in a failure in precise microstructure controlling in heat treatment. In this work, in situ observations were carried out to characterize the grain evolutions of 300M steel with varying holding time, holding temperatures, and initial microstructures. The intriguing finding was that the grain refinement by austenization of 300M steel was followed by a dramatic grain growth in the initial stage of holding (≤~600 s), and with increasing time (~600–7200 s), the average grain size appeared to have a limit value at specific temperatures. The austenization process accelerated the grain growth by generating large quantity of grain boundaries at the initial stage of holdings, and the growth rate gradually slowed down after holding for ~600 s because the driven force was weakened due to the reduction of grain boundary energy. The initial structure and the initial grain size of 300M steel had no obvious influences on the grain size evolutions. The mechanisms of grain growth were analyzed based on in situ observations and transmission electron microscope (TEM) characterizations. A grain evolution model considering the grain boundary migration of 300M steel was established for the isothermal holding process. Good agreement was obtained between the in situ observation results and the model calculation results. This investigation aimed to understand fundamentally the grain evolutions of 300M steel in the isothermal holding process.

In Situ Observation of Grain Growth and Recrystallization of Steel at High Temperature

2010 ◽  
Vol 638-642 ◽  
pp. 1077-1082 ◽  
Author(s):  
Yasuhiro Yogo ◽  
Kouji Tanaka ◽  
Koukichi Nakanishi
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Grain Growth ◽  
In Situ Observation ◽  
Initial Structure ◽  
Grain Sizes ◽  
Dynamic Observation ◽  
Average Grain Size ◽  
Observation Method

An in-situ observation method for structures at high temperature is developed. The new observation device can reveal grain boundaries at high temperature and enables dynamic observation of these boundaries. Grain growth while maintaining microstructure at high temperature is observed by the new observation device with only one specimen for the entire observation, and grain sizes are quantified. The quantifying process reveals two advantages particular to the use of the new observation device: (1) the ability to quantify grain sizes of specified sizes and (2) the results of average grain size for many grains have significantly less errors because the initial structure is the same for the entire observation and the quantifying process. The new observation device has the function to deform a specimen while observing structures at high temperature, so that enables it to observe dynamic recrystallization of steel. The possibility to observe recrystallization is also shown.

scholarly journals In Situ Hvem Study of Ion Irradiation-Induced Grain Growth in Au Thin Films

1988 ◽  
Vol 128 ◽  
Author(s):  
Joyce C. Liu ◽  
Jian Li ◽  
J. W. Mayer ◽  
Charles W. Allen ◽  
Lynn E. Rehn
Keyword(s):  
Grain Growth ◽  
Room Temperature ◽  
Ion Irradiation ◽  
Boundary Migration ◽  
Grain Boundary Migration ◽  
Average Grain Size ◽  
In Situ Observations ◽  
Au Thin Films ◽  
Grain Coalescence

ABSTRACTIn situ observations of 1.5 MeV Xe+ ion irradiated Au films at room temperature and at 150°C reveal the evolution of grain growth: the average grain size increases by the mechanisms of grain boundary migration and grain coalescence.

Grain Growth Behaviour Of Nanocrystalline Nickel

1991 ◽  
Vol 238 ◽  
Author(s):  
A. M. El-Sherik ◽  
K. Boylan ◽  
U. Erb ◽  
G. Palumbo ◽  
K. T. Aust
Keyword(s):  
Electron Microscopy ◽  
Thermal Stability ◽  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Thermal Stabilization ◽  
Growth Behaviour ◽  
In Situ Electron Microscopy ◽  
Thermal Stability Of

ABSTRACTThe thermal stability of electrodeposited nanocrystalline Ni-1.2%P and Ni-0.12%S alloys is evaluated by in-situ electron microscopy studies. Isothermal grain size versus annealing time curves at 573K and 623K show an unexpected thermal stabilization in form of a transition from rapid initial grain growth to negligible grain growth. This behaviour is discussed in terms of the various grain boundary drag mechanisms which may be operative in these alloys.

scholarly journals A brief overview on grain growth of bulk electrodeposited nanocrystalline nickel and nickel-iron alloys

2019 ◽  
Vol 58 (1) ◽  
pp. 98-106
Author(s):  
Haitao Ni ◽  
Jiang Zhu ◽  
Zhaodong Wang ◽  
Haiyang Lv ◽  
Yongyao Su ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Growth Process ◽  
Boundary Migration ◽  
Thermal Conditions ◽  
Iron Alloys ◽  
Nanocrystalline Nickel ◽  
Nickel Iron ◽  
Average Grain Size

Abstract This review focuses on grain growth behaviors and the underlying mechanisms of bulk electrodeposited nanocrystalline nickel and nickel-iron alloys. Effects of some important factors on grain growth are described. During thermal-induced grain growth process, grain boundary migration plays a key role. For similar thermal conditions, due to grain boundary mobility with solute drag, limited grain growth occurs in nanocrystalline alloys, as compared to pure metals. Nonetheless, in the case of stress-induced grain growth process, there are a variety of mechanisms in samples having various deformation histories. As an example the grain growth of nanocrystalline nickel and Ni-20%Fe alloy with nearly the same grain-size distribution and average grain size is compared in this paper. Thermal analysis indicates nanocrystalline nickel is much more prone to rapid grain growth than nanocrystalline Ni-20%Fe alloy. Nevertheless, grain growth of nanocrystalline Ni-20%Fe is found to be more pronounced than nanocrystalline nickel during rolling deformation.

Effect of Grain Boundary Energy in Recrystallization Simulation by Phase Field Method

2020 ◽  
Vol 993 ◽  
pp. 953-958
Author(s):  
Yan Wu ◽  
Ren Chuang Yan ◽  
Er Wei Qin ◽  
Wei Dong Chen
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Phase Field ◽  
Boundary Energy ◽  
Phase Field Model ◽  
Field Method ◽  
Phase Field Method ◽  
Grain Boundary Energy ◽  
Average Grain Size

In this paper, the effect of grain boundary energy in AZ31 Mg alloy with multi-order parameters phenomenological phase field model has been discussed during the progress of recrystallization. The average grain size of the recrystallization grain at a certain temperature and a certain restored energy but various grain boundary energies have been studied, and the simulated results show that the larger the grain boundary energy is, the larger the average grain size will be, and the speed of grain growth will increase with the increase of grain boundary energy. Additionally, temperature will also increase the grain growth rate.

scholarly journals Dome Concordia ice microstructure: impurities effect on grain growth

2002 ◽  
Vol 35 ◽  
pp. 552-558 ◽  
Author(s):  
Jérôme Weiss ◽  
Jérôme Vidot ◽  
Michel Gay ◽  
Laurent Arnaud ◽  
Paul Duval ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Growth ◽  
Growth Process ◽  
Boundary Energy ◽  
Ice Core ◽  
Dust Particles ◽  
The Holocene ◽  
Average Grain Size

AbstractWe present a detailed analysis of the microstructure in the shallow part (100–580m) of the European Project for Ice Coring in Antarctica (EPICA) ice core at Dome Concordia. In the Holocene ice, the average grain-size increases with depth. This is the normal grain-growth process driven by a reduction of the total grain-boundary energy. Deeper, associated with the Holocene–Last Glacial Maximum (LGM) climatic transition, a sharp decrease of the average grain-size is observed. to explain modifications to the microstructure with climatic change, we discuss the role of soluble and insoluble (microparticles) impurities in the grain-growth process of Antarctic ice, coupled with an analysis of the pinning of grain boundaries by microparticles. Our data indicate that high soluble impurity content does not necessarily imply a slowing-down of grain-growth kinetics, whereas the pinning of grain boundaries by dust particles located along the boundaries does explain modifications to the microstructure (small grain-sizes; change in grain-size distributions, etc.) observed in volcanic ash layers or dusty LGM ice.Moreover, classical mean-field models of grain-boundary pinning are in good quantitative agreement with the evolution of grain-size along the EPICA ice core. This suggests a major role for dust in the modification of shallow polar ice microstructure.

scholarly journals In Situ Observation on the Effects of Prior Martensite Formation on Nanostructured Low–Temperature Bainite Transformation

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 818 ◽  
Author(s):  
Wen Zhou ◽  
Tingping Hou ◽  
Lang Tao ◽  
Kaiming Wu
Keyword(s):  
Isothermal Holding ◽  
Martensite Plate ◽  
Parent Phase ◽  
Longitudinal Direction ◽  
In Situ Observation ◽  
Martensite Formation ◽  
Transformation Behavior ◽  
Lateral Direction ◽  
In Situ Observations

Nanobainite transformation behavior was comparably studied using in situ observations for two heat treatments: With and without partial quenching before isothermal holding at 300 °C. It was found that the prior martensite formation significantly accelerated the rate of the subsequent nanobainite transformation. Bainitic laths formed adjacent to a prior martensite plate and grew up to austenites. Bainite phase also formed both at the grain boundaries of the parent phase and inside the grains. Regarding the growth mode, bainite grows along the longitudinal direction and hardly grows along the lateral direction.

scholarly journals Anisotropic Pinning-Effect of Inclusions in Mg-Based Low-Carbon Steel

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2241
Author(s):  
Chi-Kang Lin ◽  
Hsuan-Hao Lai ◽  
Yen-Hao Su ◽  
Guan-Ru Lin ◽  
Weng-Sing Hwang ◽  
...  
Keyword(s):  
Grain Size ◽  
Carbon Steel ◽  
Grain Boundary ◽  
Low Carbon Steel ◽  
In Situ Observation ◽  
Low Carbon ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Austenite Grain Boundary

In this study, the effect of austenite grain size on acicular ferrite (AF) nucleation in low-carbon steel containing 13 ppm Mg is determined. The average austenite grain size was calculated using OM Leica software. Results show that the predicted and experimental values of austenite grain size are extremely close, with a deviation of less than 20 µm. AF formation is difficult to induce by either excessively small and large austenite grain sizes; that is, an optimal austenite grain size is required to promote AF nucleation probability. The austenite grain size of 164 µm revealed the highest capacity to induce AF formation. The effects of the maximum distance of carbon diffusion and austenite grain size on the microstructure of Mg-containing low carbon steel are also discussed. Next, the pinning ability of different inclusion types in low-carbon steel containing 22 Mg is determined. The in situ observation shows that not every inclusion could inhibit austenite grain migration; the inclusion type influences pinning ability. The grain mobility of each inclusion was calculated using in situ micrographs of confocal scanning laser microscopy (CSLM) for micro-analysis. Results show that the austenite grain boundary can strongly be pinned by Mg-based inclusions. MnS inclusions are the least effective in pinning austenite grain boundary migration.

scholarly journals Competition between grain growth and grain-size reduction in polar ice

2011 ◽  
Vol 57 (205) ◽  
pp. 942-948 ◽  
Author(s):  
Jens Roessiger ◽  
Paul D. Bons ◽  
Albert Griera ◽  
Mark W. Jessell ◽  
Lynn Evans ◽  
...  
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Boundary Migration ◽  
Boundary Energy ◽  
Ice Core ◽  
Size Reduction ◽  
Polar Ice ◽  
Average Grain Size ◽  
Log Normal

AbstractStatic (or ‘normal’) grain growth, i.e. grain boundary migration driven solely by grain boundary energy, is considered to be an important process in polar ice. Many ice-core studies report a continual increase in average grain size with depth in the upper hundreds of metres of ice sheets, while at deeper levels grain size appears to reach a steady state as a consequence of a balance between grain growth and grain-size reduction by dynamic recrystallization. The growth factorkin the normal grain growth law is important for any process where grain growth plays a role, and it is normally assumed to be a temperature-dependent material property. Here we show, using numerical simulations with the program Elle, that the factorkalso incorporates the effect of the microstructure on grain growth. For example, a change in grain-size distribution from normal to log-normal in a thin section is found to correspond to an increase inkby a factor of 3.5.

The effect of excess neodymia on the grain growth of Nd1+xBa2−xCu3Oy solid solutions

1998 ◽  
Vol 13 (10) ◽  
pp. 2819-2832 ◽  
Author(s):  
Russell B. Rogenski ◽  
Kenneth H. Sandhage ◽  
Alexander L. Vasiliev ◽  
Eric P. Kvam
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Boundary Energy ◽  
Grain Boundary Energy ◽  
Detectable Change ◽  
Fine Grained ◽  
Average Grain Size ◽  
Second Phases

The grain growth of dense, fine-grained Nd1+xBa2−xCu3Oy (x = 0.1−0.4) specimens has been examined in pure O2(g) at 938 °C and 967 °C. No detectable change in average grain size was observed for Nd1.4Ba1.6Cu3Oy within 72 h at 967 °C; however, a significant increase in average grain size developed between 18 and 24 h at 967 °C for Nd1.3Ba1.7Cu3Oy, and within 8−12 h at ≤967 °C for Nd1.2Ba1.8Cu3Oy and Nd1.1Ba1.9Cu3Oy. Microstructural analyses revealed that sudden changes in average grain size coincided with the formation of relatively large (abnormal) grains. A broadening of the grain size distribution was also observed. TEM analyses revealed that grain boundaries were free of second phases. The possible role of anisotropy in grain boundary energy and/or mobility on grain growth is discussed.

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