Abstract
Although significant advances in tool material development have been made to facilitate increased metal removal rates when turning steels and cast irons, no equivalent developments have been made for cutting titanium alloys. In this paper, part of a recent research programme is described in which the principal wear mechanisms of ceramic and cemented carbides (coated and uncoated) used for turning Ti–6AI–4V (IMI 318) and commercial purity titanium are investigated. A significant problem is the generation of rake face temperatures above 900°C at relatively low cutting speeds, i.e. ∼75 m min−I, which promote rapid rake face crater wear by dissolution–diffusion. Of all the tool materials tested, it was the ‘straight‘ grade (WC–Co) cemented carbides which were most resistant to this type of wear. They also offered superior resistance to flank wear induced by attrition. Experiments in which cubic boron nitride was used and comparative tests with TiB2 and TiC coated carbides, in conjunction with solubility considerations, suggest that boron–based tool materials have significant potential for combating wear caused by dissolution–diffusion.
MST/245
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