Mössbauer spectroscopy and its application to the characterization of heat treated parts

Pechoušek Jiří - Palacký University Olomouc (Czech Republic)

It is of great importance to the steel industry as a whole that research is conducted into measurement methods for the heat treatment of steels, in order that quality, efficiency and innovation can be assured. The application of advanced measurement methods allows engineers and technicians to gain a deeper understanding of, and to optimize, heat treatment processes. Moreover, sophisticated measurement techniques facilitate a more detailed comprehension of the microstructure and intrinsic characteristics of newly developed steels. The implementation of validated and standardized methods ensures the consistency and comparability of results across different manufacturers and laboratories. This contribution presents the application of Mössbauer spectroscopy in the steel industry. Mössbauer spectroscopy is a nuclear analytical technique in which the examined iron atom serves as a probe of the material’s structure, thereby enabling the examination of all iron-containing phases present in steels. A radioactive source of 57Co (which transitions by radioactive decay to 57Fe) is employed to irradiate the examined material in a defined manner. The type and energy of the radiation detected, as well as the composition of the material in question, determine the thickness of the surface layer that can be analyzed, which can range from several tens of nanometers to several tens of micrometers. The method permits the non-destructive measurement of the quantity of austenite (retained austenite) i.e., and other partial phases present in steels. It is possible to measure entire machine parts, their surfaces, as well as cuts and sections commonly prepared for metallographic analyses. The majority of measurements are conducted in the surface layer thickness range of up to 10 µm. The results are expressed in atomic percent (at. %) of the number of iron atoms in the given phase. The aim of this contribution is to present the method and its application.