| Steel bonded titanium carbide (SBTC), which has low proportion, high hardness, good high-temperature stability, advantageous machining and heat treatment performance, has been widely used in making industry molds, measuring tools, rigid shock-resistant parts. It is important materials of preparation wear-resistant parts that were used in aerospace, aviation, ships and weapons. At present, compares with the foreign productions, the SBTC of China's military and high-tech areas mainly relies on domestic production, which has high porosity, uneven texture and low strength, often exists some problems such as low machining yield, low abrasion ability etc. during machining and application. Powder metallurgy (PM) technology can manufacture metal matrix composites with different proportions'raw powder or complex compositions, and liquid phase sintering technology can strongly combine TiC and steel matrix, therefore, endow the alloy with excellent mechanical and wear resistance properties. SBTC was prepared by PM here, and the influences that preparation process, carbonyl iron powder substituting of reduced Iron powder and adding rare earth into raw powder on alloy's performance were studied, as well as alloy densification method and interface structure. Main results are as follows:The Fe-3.0Cr-3.0Mo-0.5Cu-0.5C-33TiC alloy was prepared by liquid phase sintering technology in the condition of vacuum degree below4.5×10-1pa. The influences of powder processing, pressing process and sintering process on alloy were evaluated. Alloying reaction happened between Fe and Mo, C, Cu, Ni, and the solid solution of Fe formed during high-energy ball milling. Billet's density increased with pressing pressure rising, however, alloy's bending strength, hardness and density by cold isostatic pressing (CIP) were higher than moulding pressing (MP) in same pressure. Within a determinate range, alloy's bending strength, hardness and density improved with the final sintering temperature and heat preservation time increasing, and the best comprehensive performances acquired by1420℃/1h.SBTC was prepared with the same constituents in which carbonyl iron powder substituted reduced iron powder partly. The study found that adding Carbonyl iron powder can promote powder's forming performance, pressure density, sintering process and decrease sintering temperature. The study revealed that carbonyl iron powder, which filled into the space among large particle in mold process and rolled in press process, can improve formability, and can promote sintering process because of specific surface area and reducing atom migration distance. Via sintering at1400℃, the hardness of alloy, which contained30%Carbonyl iron powder, improved to81.8HRA from77.5HRA, and the bending strength improved to1447Mpa from1123Mpa.SBTC containing micro rare earth (RE) was prepared, and the different influence that Fe-RE and CeO2on alloy's properties was investigated, the results showed that adding Fe-RE was better than CeO2. RE made powder deoxygenation, holding carbon and improving wetting during milling and sintering, therefore improving the densification process and decreasing porosity. In the course of liquid phase sintering, RE gathered at the surface of TiC particle and reduced surfacial energy, therefore, the dissolving-precipitating process of TiC in molten iron was inhibited, furthermore, the growing up of TiC grain was inhibited. The performance of alloy adding0.8%Fe-RE was the best.The influence of forging and hot isostatic process (HIP) on SBTC was studied. The study showed that forging plastic was markedly improved and cracking significantly reduced using own designed forging die, by which alloy suffered multi-directional stresses. The size of pore in alloy decreased or disappeared by forging, TiC and the other carbides brittle phase were broken into refinement and distributed more homogeneous, therefore, alloy's mechanical performance improved. The ideal parameters of HIP is140MPa/1260℃/0.5h by range analysis. The defects in alloy such as pore, which formed during sintering process, reduced or disappeared after HIP. Alloy's structure and performance improved more remarkable such as hardness to86.8HRA, bending strength to1677MPa, by incorporation of forging and HIP.The study on interface structure showed that TiC dissolved and precipitated in molten iron during sintering and HIP. With heat preservation time increasing, fine TiC particles decreased or disappeared, large TiC particles grown larger and appeared more smoothly. Components transition happened at the interface without interfacial reactionts, and had a larger bonding strength. Fracture analysis revealed that matrix fracture with quasi-cleavage features, the features of TiC fracture depended on particle size, the larger(>2μm) with cleavage fracture, the smaller(<1μm) with intergranular fracture characteristics.
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