A Study Of The Microstructure And Wear Behavior Of High Tungsten White Cast Iron

Wear-resistance materials have been strongly demanded for various industrial applications, such as mining, cement industry and powder generation systems. Great effort has been made to produce wear-resistance materials which can mitigate mechanical attack effectively. High chromium white cast iron has been used as standard wear-resistance materials since1960s. Because of the demands in upgrading the productivity, high tungsten white cast iron which is considered as a potential wear-resistance material have attracted more attention recently.In this work, a novel high tungsten white cast iron has been produced for applications which require excellent abrasion resistance. The results indicated that the Fe-W-C alloy can present hypoeutectic, eutectic or hypereutectic structures depending on the content of carbon elements. The high tungsten white cast iron which contain25wt.%W element and3wt.%C element is composed with M6C, M7C3, martensite and austenite. It is found that the primary blocky M6C carbides with an average size of25μm distributed uniformly among the matrix. The Vickers microhardness measurements of M6C carbide show that the HV is high up to-1920. Due to high hardness, it is promising that M6C carbides can be taken as reinforced phase that embedded in the matrix to improved the wear resistance. Study on the morphologies, chemical composition and formation process of M6C carbide has also been made.To investigate the influence of solidification conditions on the microstructure and mechanical properties, the samples were obtained under different solidification rates. The morphology of primary M6C carbides were obviously changed under the influenced of solidification rate. M6C carbide under high solidification rate shows a great tendency to present petal shape, while the blocky M6C almost disappeared. The hardness of petal-like M6C is lower than the blocky M6C.The wear behavior of the high tungsten white cast iron was studied by three-body abrasive wear tester. With the protecting effect of the M6C carbides and the supporting effect of the matrix on particles, the high tungsten white cast iron presented excellent wear-resistance property. As the results have demonstrated, the wear volume loss of the high tungsten white cast iron was much less than high chromium white cast iron, but the difference in wear volume loss between the high tungsten white cast irons under different solidification rates was small. The microstructure of wore part of the samples were characterized by the scanning electron microscope.