Structure and Solidification Process Observation of Fe-C-Cr Alloy Using Confocal Laser Scanning Microscope

¹ Department of Production Systems Engineering, Faculty of Engineering, Muroran Institute of Technology, 27-1, Mizumoto, Muroran, Hokkaido, Japan
² Department of Metal Frontier Engineering, Faculty of Engineering, Tohoku University, 2-chome 1-1, Aoba-ku Katahira, Sendai, Miyagi, Japan

^* Corresponding author: 19042005@mmm.muroran-it.ac.jp

Abstract

In this study, we investigated the growth process of M7C3 carbide by a Confocal Laser Scanning Microscope. Fe-C-Cr alloy was prepared using an arc furnace. The composition was determined to be Fe:C:Cr=55:5:40(wt%). From the results of XRD and EPMA, the Fe-C-Cr alloy contained M₇C₃ carbide in the internal structure. In condition of two cooling rates 60°C/min and 30°C/min observed with a Confocal Laser Scanning Microscope. Corners of the Hexagonal structure grew in the preferred orientation direction of M₇C₃ carbide at 60°C/min. After the growth of preferred orientation direction, the M₇C₃ carbide formed to connect between the corners. At a cooling rate of 30°C/min, M₇C₃ carbides grew in oblique direction to the observation area. At the beginning, the structures were hidden in the fluid. But the structures started to grow, the shape of the hexagon became eventually. After the melting experiment, the samples were observed by Optical Microscope and Scanning Electron Microscope. As a result, since hexagonal structure arose a difference in height between the outside and the inside. M7C3 carbides grew from the outside in the solidification process.