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Article

Change in Primary (Cr, Fe)7C3 Carbides Induced by Electric Current Pulse Modification of Hypereutectic High Chromium Cast Iron Melt

1
Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China
2
Research Center for Analysis and Measurement, Kunming University of Science and Technology, Kunming 650039, China
3
School of Materials and Chemical Engineering, Chongqing University of Arts and Sciences, Chongqing 402160, China
*
Author to whom correspondence should be addressed.
Materials 2019, 12(1), 32; https://doi.org/10.3390/ma12010032
Received: 17 November 2018 / Revised: 13 December 2018 / Accepted: 14 December 2018 / Published: 22 December 2018
In this work, an electric current pulse (ECP) of 500A was applied on a hypereutectic high chromium cast iron (HHCCI) melt before it began to solidify, and the effect of ECP on primary carbides was investigated. The characteristics of the primary carbides were analyzed by X-ray diffraction (XRD), electron probe micro-analyzer (EPMA), transmission electron microscopy (TEM), micro hardness tester, and other techniques. The results showed that ECP not only refined the primary (Cr, Fe)7C3 carbides, but also decreased the average content of Cr in the primary carbides. At the same time, the average value of micro hardness of the primary carbides increased by about 84 Kgf/mm2, which contradicts existing knowledge that hardness increases with an increase in Cr content. XRD analysis showed that the crystal structure of the primary carbides did not change. The results of EPMA indicated that the Cr/Fe ratio gradually decreased from the center to the edges of the carbide particles. Further investigation revealed that the uneven distribution of elements caused by ECP led to an increase in defects (including twins, antiphase boundaries, and dislocations). This increase in defect density is the main reason for the increase in micro hardness instead of the expected decrease. The mechanism of the change in primary carbides was analyzed in detail in this paper, which has provided a new method for the refinement of primary carbides and for improving the properties of primary carbides. View Full-Text
Keywords: (Cr, Fe)7C3; electric current pulse; micro defect; micro hardness (Cr, Fe)7C3; electric current pulse; micro defect; micro hardness
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MDPI and ACS Style

Geng, B.; Zhou, R.; Li, L.; Lv, H.; Li, Y.; Bai, D.; Jiang, Y. Change in Primary (Cr, Fe)7C3 Carbides Induced by Electric Current Pulse Modification of Hypereutectic High Chromium Cast Iron Melt. Materials 2019, 12, 32. https://doi.org/10.3390/ma12010032

AMA Style

Geng B, Zhou R, Li L, Lv H, Li Y, Bai D, Jiang Y. Change in Primary (Cr, Fe)7C3 Carbides Induced by Electric Current Pulse Modification of Hypereutectic High Chromium Cast Iron Melt. Materials. 2019; 12(1):32. https://doi.org/10.3390/ma12010032

Chicago/Turabian Style

Geng, Baoyu, Rongfeng Zhou, Lu Li, Haiyang Lv, Yongkun Li, Dan Bai, and Yehua Jiang. 2019. "Change in Primary (Cr, Fe)7C3 Carbides Induced by Electric Current Pulse Modification of Hypereutectic High Chromium Cast Iron Melt" Materials 12, no. 1: 32. https://doi.org/10.3390/ma12010032

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