Pinpoint Microstructure Characterization Technique by Transmission Electron Microscopy

The advancement of transmission electron microscopy has made it possible to analyze the metallographic structure of steel products on a nanoscopic scale, which leads to the detail understanding of microstructures such as fine precipitates and grain boundaries. The application of the characteristic technology to commercial steel products requires consistency in the structural analysis of steel from a macroscopic to a nanoscopic scale. As a solution, a technique for pinpoint analysis of ultra-fine structures of steel has been established through the combination of the focused ion beam technique with a manipulator that can work in a focused ion beam device. Microstructural analyses of a galvannealed coating surface and an intragranular precipitate that triggers phase transformation are described herein as examples of the application of the established technique to commercial steel products. These examples show the effectiveness of the developed technique in solving problems of coating surface quality and refining the metallographic structure of welded joints through a nanoscopic material design approach.