Experimental Evaluation of Tool and High-Speed Steel Properties Using Multi-Functional KIc-Test Specimen



Normally, hardness and fracture toughness are used to determine the influence of vacuum-heat-treatment parameters and to optimize it for the specific operating conditions of the tool. However, there are also other tool properties which are equally important and need to be taken into consideration. To determine such a wide range of properties different test procedures and different test specimens are required since none of the standard tests alone is capable of providing relevant properties completely. Currently the best overall appraisal of tool and high-speed steel applicability seems to be a combination of fracture toughness, bending, or compression testing and in specific cases of impact or small-punch creep test. This paper clearly demonstrates usability of a single KIc-test specimen for determination of a wide range of properties being important for tool and high-speed steels, and their vacuum-heat-treatment optimization. In the case of ESR AISI M2 high-speed steel low tempering and austenitizing temperatures are preferable in terms of ductility and toughness, high tempering and lower austenitizing temperatures in terms of bending strength and high-speed machinability, while high austenitizing and mid tempering temperatures in terms of hardness, compression strength and grindabillity.