On the evolution of secondary hardening carbides in a high-speed steel characterised by APFIM and SANS

Abstract

Abstract Secondary hardening carbides in high-speed steels are very important microstructural constituents, responsible for the excellent properties of this type of steel. Therefore, detailed knowledge about their precipitation behaviour with respect to type, size and chemical composition is of paramount interest. Atom probe field ion microscopy and small-angle neutron scattering have emerged to be important techniques for the characterisation of nanometre-sized precipitates, such as secondary hardening carbides. In this paper, the precipitation behaviour of the high-speed steel HS6-5-2 with the nominal composition (in wt.%) Fe-0.9C-4.1Cr-6.4W-5Mo-1.8V was investigated. Differently tempered specimens were analysed to determine size, volume fraction and chemical composition of the secondary hardening carbides using a three-dimensional tomographic atom probe and small-angle neutron scattering. The results obtained from both techniques were compared with emphasis on the chemical composition of the precipitates.