Development of quantification methods applied to HSS alloys for carbides volume fraction and grain size assessments

High speed steels (HSS) are used in applications where enhanced mechanical properties together with hot oxidation and wear resistances are required. Such an improved physico-chemical behaviour is mainly due to the presence of primary carbides within the microstructure. Depending of the initial chemical composition several types of carbides can precipitate in HSS such as MC (Nb and V-rich), M2C (Mo and W-rich), Cr-rich M7C3, etc. Two groups of HSS were analysed in this study, which are the so-called cast HSS grades that are manufactured by a centrifugal casting process and the cladded HSS manufactured by laser cladding.

Purpose: Quantify the carbide volume fractions and the grain size within HSS grades in order to set correlations between the microstructure and both the mechanical and the tribological properties of the materials.

Findings: The metallurgical features such as carbides nature and shape have been determined that are related to the manufacturing process of the studied material, and several methods have been used to quantify the carbide volume fractions and to assess the grain size.