Wear of Coated Tungsten Carbide Tool In Cutting H.S. Steel Ⅱ

In last part we know that generally (Al,Cr)N coated tungsten carbide tool has a slower tool wear progress because of the coating film has higher hardness and higher oxidation temperature. This part is an introduction of the whole article, explaining why the author choose tungsten carbide tool coated with (Al,Cr)N and hardened sintered steel as study objects.

1.Introduction

A machine part having a complicated shape can be mass-produced accurately by powder metallurgy. A diffusion alloyed powder or a completely alloyed powder is usually used as an alloyed powder for the sintered steel. The compressibility of the diffusion alloyed powder is better than that of the completely alloyed powder. After the sintering, the sintered material is quenched and tempered to improve the mechanical properties and wear-resistance. For dimensional accuracy, it is often necessary for the sintered steel machine parts to be machined by the metal removal process. As the sintered machine parts are often cut at high cutting speed for mass-production, the tool materials must have good wear resistance. The polycrystalline cubic boron nitride compact (cBN) seems to be an effective tool material because it has good heat resistance and wear resistance. However, in milling, a major tool failure of cBN readily occurs by fracture because cBN has poor fracture toughness. Coated cemented tungsten carbide tools, which have good fracture toughness and wear resistance, seem to be effective tool materials. TiN, Ti(C,N) and (Ti,Al)N are generally used for the coating film. So, there are many studies on the wear-resistance of these coating layers. Although there are some studies on the tool wear characteristics of the PVD coated cemented tungsten carbide tools in the cutting of the hardened steel or the sintered steel, there are few studies on tool wear in the cutting of the hardened sintered steel.

 (To be continued. This article is divided into several parts. Here is part 2. For part 1, please refer to http://news.chinatungsten.com/en/tungsten-information/80613-ti-10422; for part 3, please refer to http://news.chinatungsten.com/en/tungsten-information/80615-ti-10432)

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