In Situ Observation of Changing Crystal Orientations During Austenite Grain Coarsening

2014 ◽  
pp. 109-129
Author(s):  
Hemant Sharma ◽  
Richard M. Huizenga ◽  
Aleksei Bytchkov ◽  
Jilt Sietsma ◽  
S. Erik Offerman
Keyword(s):  
In Situ Observation ◽  
Grain Coarsening ◽  
Austenite Grain ◽  
Crystal Orientations

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.

In Situ Observation of Catalyzed Gasification of Graphite by Nickel

1981 ◽  
Vol 39 ◽  
pp. 76-77
Author(s):  
R. T. K. Baker ◽  
R. D. Sherwood
Keyword(s):  
Objective Lens ◽  
In Situ Observation ◽  
Gas Flows ◽  
Catalytic Gasification ◽  
Television Camera ◽  
Viewing Screen ◽  
Fuels And Chemicals ◽  
Gasification Of Carbon ◽  
Transmission Microscope

The catalytic gasification of carbon at high temperature by microscopic size metal particles is of fundamental importance to removal of coke deposits and conversion of refractory hydrocarbons into fuels and chemicals. The reaction of metal/carbon/gas systems can be observed by controlled atmosphere electron microscopy (CAEM) in an 100 KV conventional transmission microscope. In the JEOL gas reaction stage model AGl (Fig. 1) the specimen is positioned over a hole, 200μm diameter, in a platinum heater strip, and is interposed between two apertures, 75μm diameter. The control gas flows across the specimen and exits through these apertures into the specimen chamber. The gas is further confined by two apertures, one in the condenser and one in the objective lens pole pieces, and removed by an auxiliary vacuum pump. The reaction zone is <1 mm thick and is maintained at gas pressure up to 400 Torr and temperature up to 1300<C as measured by a Pt-Pt/Rh 13% thermocouple. Reaction events are observed and recorded on videotape by using a Philips phosphor-television camera located below a hole in the center of the viewing screen. The overall resolution is greater than 2.5 nm.

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