Micro-tensile testing for strength characterization of high-speed steel

The high-speed steel PM HS3–3-4 was investigated to assess the influence of an isothermal holding stage within the transformation gap during quenching on the interfacial strength between the matrix and carbides. The interfacial strength was assessed by micro-tensile testing using push-to-pull geometries fabricated via focused ion beam (FIB) milling. During indentation, the gauge section was continuously recorded by scanning electron microscopy (SEM) and strain analysis was conducted by digital image correlation (DIC). Tensile strengths of 2150–2500 MPa, unaffected by the isothermal holding stage, were measured together with significant plastic deformation in the martensitic matrix. Fracture occurred within the matrix in close proximity to the interface. • Push-to-pull micro tensile geometry fabricated by focused ion beam milling. • Carbide–matrix interface in high-speed steel characterized by micro tensile testing. • Interfacial strength exceeds the cohesive strength of the martensitic matrix. • Digital image correlation deriving stress-strain curves from micro tensile testing.