Effects of Chemical Composition and Solidification Rate on the Solidification Behavior of High-Cr White Irons

• Published in: Metals (Basel ) Vol. 14; no. 3; p. 276
• Main Authors: Son, Hee Young, Jung, In Yong, Choi, Baig Gyu, Shin, Jong Ho, Jo, Chang Yong, Lee, Je Hyun
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.03.2024
• Subjects: Alloys; Austenite; Carbides; cellular solidification; Cellular structure; Chemical composition; Cooling; dendritic solidification; Directional solidification; Eutectic alloys; Freezing; high-Cr white iron; Lee, J.H; M7C3/austenite eutectic structure; Mechanical properties; Microscopy; Microstructure; Molecular composites; Morphology; primary austenite dendrite; Solids; Variables; White iron; South Korea; Japan
• ISSN: 2075-4701; 2075-4701
• DOI: 10.3390/met14030276

The effects of chemical composition and solidification rate on the solidification behavior of high-Cr white irons were investigated through directional solidification. Increasing the solidification rate in hypoeutectic alloys caused finer dendrite-arm spacing, as expected. The eutectic structure, which formed in the interdendritic region, was comprised of M7C3 and austenite; however, secondary dendrite arms of hypoeutectic alloys contained a few M7C3 particles that solidified prior to the eutectic structure. The transition from cellular to dendritic solidification occurred at a solidification rate between 50 µm/s and 100 µm/s in a near-eutectic alloy. In the near-eutectic alloy with cellular solidification, a directionally arrayed in-situ composite of M7C3/austenite formed within the cell. Speckle-like features appeared in the intercellular region due to M23C6 carbide precipitation during subsequent cooling after freezing. Like dendrite-arm spacing in hypoeutectic alloys, the inter-speckle spacing and the inter-fiber spacing became finer with an increasing solidification rate in the cellular solidification range.