Study On The Cemented Carbide Tools With Fe And Ni Binder Phase For Steel Cutting

Since Karl Schroter invented WC-Co cemented carbide by the powder metallurgy technology in 1923, cobalt is the main binder phase all along, but Co is expensive and rare and its' reserves all over the world is very finite. Fe, Ni and Co all belongs to iron family metals in the periodic table of elements. Their physical and chemical properties are quite similar. The Ni resources are also not rich, but the Fe resources are very abundant. Therefore, Fe substitute for Co as the binder phase of cemented carbide has an important strategic and economic significance.According to the usage classification, the cemented carbide can be classified as four types: K, P, M and G. Fe replace entirely Co as binder phase is not often used, but Fe substitute for Co partly in G sort cemented carbide is generally used for mining tools, petroleum drilling, geological exploration etc. But if they are used to cut steel which need high hardness and abrasion performance, cemented carbides with Fe and Ni binder phase are confronted with the problems as follows:①The two phase zone of WC+Fe is too narrow to control the carbon content.②Tools with Fe binder phase is easy to be eroded seriously.③The tools and steels are easy adhere to each other at the cutting process. This paper researched on improving the performance of the cemented carbide tools with Fe binder phase prepared by adding Ni and TiC, optimizing carbon controlling range and sintering process and coating technology, and also studied the influences of these factors upon the microstructure and performance of the alloy.First of all, the influence of Ni and TiC on the structure and performance of cemented carbide and the best content of carbon were studied by preparing four kinds of cemented carbide with five grade carbon contents respectively. They were WC+Fe, WC+TiC+Fe, WC+Ni+Fe and WC+TiC+Ni+Fe cemented carbides. The results show that Ni and TiC can greatly enlarge carbon zone and reduce the difficulty of craft. The Ni can also obviously increase transverse rupture strength and TiC can increase hardness of the alloy. By comparing their structure and performance, we can conclude that WC+TiC+Ni+Fe cemented carbide has the best general performance among the four kinds of alloys. And the best content of carbon is around 5. 91%.Then we prepared the WC+TiC+Ni+Fe cemented carbide through sintering them at the temperature of 1360℃, 1400℃, 1440℃and 1480℃respectively to research the influence of the sintering temperature on the performance of the alloy. The results show that the alloy sintered at 1440℃has the best performance. The hardness and the transverse rupture strength are 91. 6HRA and 1720MPa respectively. Therefore the 1440℃is the best sintering temperature.Finally, in order to estimate the performance of the WC+TiC+Ni+Fe cemented carbide further, we prepared pure Fe binder cemented carbide and pure Co binder cemented carbide (WC+TiC+Fe, WC+TiC+Co). After coating the alloys, we studied their performance especially cutting performance. The results indicate that the cohesion strength between coating and substrate with Fe binder phase is better. The transverse rupture strength of WC+TiC+Ni+Fe cemented carbide with coating or not are as the same as WC+TiC+Co. And coating could prevent Fe binder phase cemented carbide from rust. And the abrasion resistance of WC+TiC+Fe, WC+TiC+Ni+Fe and WC+TiC+Co cemented carbide tools without coating are about the same. And the impact resistance increase as transverse rupture strength enhancing. Three kinds of coated tools' machinability are good in the continuous cutting. And the coating can prevent the tools from adhering to the steels.