Steel bonded cemented carbide is a kind of composite material with hard soluble metal carbides (mainly WC, TiC, etc.) as hard phase and steel as bonding phase. The hard phase of steel bonded cemented carbide generally accounts for 30%~50% of the total alloy quality and the rest is steel matrix. Because of the large proportion of steel matrix, the properties of steel are more obvious. It has good machinability, heat treatment and Forgability. After the process of powder mixing, pressing, sintering, forging, cutting, heat treatment and so on, all kinds of steel bonded carbide products of various sizes and shapes can be obtained. It is very extensive. The mechanical properties of steel bonded cemented carbide are between hard alloy and steel. Compared with steel, they have higher hardness, better wear resistance and higher modulus of elasticity and compressive strength. Compared with hard alloys, they have good bending strength and impact toughness, good self lubrication, lower friction coefficient and excellent chemical stability. Qualitatively, it shows excellent comprehensive performance. Its hardness can reach HRC60~70, while toughness index is much improved than ordinary cemented carbide. Under the condition of annealing, it can be machined by vehicle, milling, planing, grinding and drilling by ordinary cutting equipment and cutting tools. It can also be forged and welded. In hardened state, it has high hardness. The wear resistance of high hardness and hard alloy can be close to that of high cobalt cemented carbide, and higher alloy die steel has higher modulus of elasticity, wear resistance, compressive strength and bending strength than high alloy die steel. Because of the above characteristics, steel bonded cemented carbide has special advantages in steel products. More importantly, the price of steel cemented carbide is less than half of the ordinary hard alloy, and the service life is several times, several times, even hundreds of times of steel, which has great economic benefit. Steel bonded hard alloy products can be treated with various heat treatment operations to meet the requirements of different moulds in use. Especially after quenching and tempering, the structure of the tempered martensite + alloy carbide + uniform distribution hard phase can be obtained, and the strength, hardness and toughness of the mould materials are guaranteed. Performance requirements, at the same time improve the wear resistance of the mold, and can also be used in the key parts of the mold in the way inlay, improve the quality of the product processing and processing precision.

The composition range of steel cemented carbide is widening, and it is extending to two ends. One head is extended to the field of hard alloy, the content of hard phase can be increased to up to 92%. The other is extended to the high speed steel field, and the content of the steel matrix can be increased to up to 90%. By selecting different kinds of steel and binder as binder, the alloy with specific properties can be prepared to meet the requirements of various application fields.

In recent years, it has been found that the properties of steel bonded cemented carbide with iron rich Fe-Co-Ni as binder are even better than that of WC-Co cemented carbide, because the alloy can be strengthened by martensitic transformation, precipitation hardening and ordered disordered phase transition in the Fe-Co-Ni system, and its bending strength is equal to that of ordinary hard alloy, and its comprehensive properties are excellent. It is also found that the addition of 0.4%~0.8% rare earth elements in the alloy has a great influence on the microstructure and properties of the alloy. For example, rare earth elements cerium and lanthanum react with reactive oxygen and sulfur in the system during ball milling to form stable sulfur oxides, which play the role of desulfurization and deoxidization. It is also reported that a proper amount of nano TiN is added to the TiC based steel cemented carbide, and the fine TiN "inlay" in the grain boundary of the larger TiC grain can inhibit the growth of TiC grain and hinder the bridging of the hard phase. At the same time, nano particles as interstitial particles filled into larger particles in the hard phase voids, can increase the density of materials. (Gang Yan)