Fast times in HSS: new alloys improve the performance of HSS cutting tools

摘要

Although the overall market share of high-speed steel tools is declining vis-a-vis solid-carbide ones, HSS remains a cost-effective alternative for applications where tool toughness is paramount. The continued viability of HSS is largely attributable to the single greatest advancement in the technology of HSS: the advent of powder, or particle, metallurgy (P/M). Introduced by the specialty steel industry in 1970, this method for processing HSS significantly boosts the material's properties and enables it to retain its inherent wear-resistance, as well as approach the hardness levels of carbides. Basically, the process entails induction melting of a pre-alloyed tool steel. While still in a liquid state, the metal is processed through a gas atomizer, like perfume sprayed from a bottle. Unlike perfume, though, the metal quickly solidifies into uniform particles, which, after encapsulation in a large, compressible cylinder, undergo what's known as hot isostatic pressing (HIP). Afterwards, the steel is forged or hot-rolled.