Microstructure and Wear Performance of Cobalt-Containing Iron-Based Slag-Free Self-shielded Flux-Cored Wire
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JMEPEG https://doi.org/10.1007/s11665-019-04002-5
Microstructure and Wear Performance of CobaltContaining Iron-Based Slag-Free Self-shielded FluxCored Wire Dashuang Liu, Weimin Long, Mingfang Wu, Leijun Li, Jiayou Wang, and Yu Zhang (Submitted May 7, 2018; in revised form October 5, 2018) A new type of cobalt-containing iron-based slag-free self-shielded flux-cored wire was developed for hardfacing. The influence of cobalt additions on the microstructure and wear performance of the hardfacing was investigated. The cobalt-containing iron-based hardfacing alloy has a typical hypereutectic microstructure consisting of primary M7(C, B)3 carbide, and a eutectic of M3(C, B) carbide and austenite (part of which subsequently transformed into martensite). Cobalt promoted the formation of austenite and changed the morphology of the primary carbide and eutectic colonies. The morphology of primary carbide became fragmented with increasing cobalt due to the possible impeding effect of cobalt to the movement of the M7(C, B)3/liquid interface. Different structures of the eutectic carbides were observed—the chrysanthemum structure for 1.42 wt.% cobalt, the skeleton form for 2.88 wt.% cobalt, the radial stripe 4.37 wt.% cobalt and the discrete stripe for 5.75 wt.% cobalt. Wear loss of the hardfacing alloy containing 2.88 wt.% cobalt was the smallest among all the alloys, owing to the large primary large carbide and skeleton-shaped eutectic carbides, the proper amount of austenite phase separating the M7(C, B)3 and M3(C, B) carbides, the solid solution strengthening by cobalt in the matrix, and the high hardness of the alloy. Moreover, the wear resistance has a tendency to decrease with the increase in velocity as well as load. Keywords
cobalt-containing iron-based self-shielded flux-cored wire, microstructure, wear resistance
1. Introduction The weld deposition of hardfacings is frequently employed to increase the life of components such as sugar industry, agriculture and mining industries in abrasive environments (Ref 1, 2). Several welding techniques such as shielded metal arc welding (SMAW) (Ref 3), gas metal arc welding (GMAW) (Ref 4), submerged arc welding (SAW) (Ref 5, 6) and flux-cored arc welding (FCAW) (Ref 7) can be used for hardfacing. One of the most important differences among these techniques lies in the weld deposition efficiency (Ref 8, 9). To increase the efficiency of welding, we have developed a series of slag-free self-shielded flux-cored wire with continuity of welding process, high-speed melting, without
Dashuang Liu, School of Material Science and Engineering, Jiangsu University of Science and Technology, Zhenjiang 212003, China; Zhengzhou Research Institute of Mechanical Engineering Co., Ltd., Zhengzhou 450001, China; and Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Canada; Weimin Long, Zhengzhou Research Institute of Mechanical Engineering Co., Ltd., Zhengzhou 450001, China; Mingfang Wu and Jiayou Wang, School of Material Science and Engineering, Jiangsu University of Scie
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