Microstructure and Mechanical Properties of Millimeter WC Particle-Reinforced High-Chromium Cast Iron Composites
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JMEPEG https://doi.org/10.1007/s11665-019-04491-4
Microstructure and Mechanical Properties of Millimeter WC Particle-Reinforced High-Chromium Cast Iron Composites Ping Li, Xiao Li, Yongcun Li, Mengying Gong, Chen Tian, and Weiping Tong (Submitted May 16, 2019; in revised form November 6, 2019) WC particle/HCCI composites were prepared using liquid-phase sintering technology. In this study, millimeter WC particles were used to ensure that minimal WC particle performance was compromised during the preparation process. Moreover, with the aim of controlling the evolution of microstructures and secondary carbide precipitation in the matrix, different heat treatment methods were adopted in the manufacturing process. The microstructures of the composites were investigated via SEM, XRD, EPMA and TEM. The results showed that perfect metallurgical bonding was formed between the LCS and the WC/ HCCI composites, and the width of the diffusion layer was 120 to 129 lm after heat treatment. A large number of secondary carbides precipitated in the matrix during heat treatment, and martensite formation occurred in the matrix during the subsequent cooling process, which effectively increased the microhardness of the matrix. The impact toughness of the LCS-toughened composites after heat treatment was 1.6 times that of the WC/HCCI composites, and the shear strength was 5 times that of the as-cast composites. The wear resistance of the composites under quenching at 950 °C and tempering at 220 °C was 5 times that of the as-cast composites. Keywords
abrasive wear, heat treatment, high-chromium cast iron, mechanical properties, microstructure, millimeter WC particles
1. Introduction WC particle-reinforced high-chromium cast iron matrix composites have attracted extensive attention due to their excellent comprehensive properties. This kind of composite material has been widely used in metallurgy, mining, coal, chemical and other wear-resistant industries. The main reason is the combination of the high toughness of the metal matrix and the high wear resistance of reinforced ceramics (Ref 1). These composites are expected to replace traditional metal materials in many industrial fields. Since WC particles have extremely high hardness, a high melting point, good wettability with molten metal and good wear resistance, the interface of the particle-reinforced composites is good (Ref 2). Moreover, the size of WC particles is also a key factor in the preparation of composites (Ref 3). When the particle size is small, the melting degree of the particles increases in the high-temperature liquid region, and most or even all of the WC particles are melted and diffused, which causes the original excellent properties to be lost. When
Ping Li, Xiao Li, Yongcun Li, Mengying Gong, Chen Tian, and Weiping Tong, Key Laboratory of Electromagnetic Processing of Materials, Northeastern University, Shenyang 110819, China. Contact e-mails: [email protected], [email protected], [email protected], [email protected], [email protected], and [email protected]
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