Mössbauer study of thermal behavior of CL20ES and CL50WS steel powders used in selective laser melting

Abstract

The phase and structural changes of steel powders CL20ES and CL50WS used in additive manufacturing were studied by Mössbauer spectroscopy and X-ray diffraction. Investigated powders were annealed in the temperature range 500 °C–1100 °C in oxidizing and inert atmosphere. Annealing in an oxidizing atmosphere resulted in the formation of different iron oxides in both steel powders depending on the annealing temperature. In addition, a phase change of ferrite to austenite was identified when annealing CL50WS steel powder in an oxidizing atmosphere. This phase change was confirmed by annealing given CL50WS steel powder in an inert nitrogen atmosphere. The transformation of austenite to ferrite phase was observed only, when annealing CL20ES steel powder in an inert atmosphere at 1100 °C. Morphological changes on the surface of the spherical powders were observed by scanning electron microscopy.

Zinc Ferrite Nanoparticle Coatings on Austenitic Alloy Steel

“…The transmission Mössbauer spectroscopy was employed to exclude the formation of any amorphous phases and to monitor any changes in a close proximity of the Fe atoms. The fitting model for the room-temperature Mössbauer spectra included a singlet for the austenitic stainless steel and a doublet for the zinc ferrite (Figure 11a) [11,31]. The presented transmission Mössbauer spectra exhibited significant changes in the doublet's quadrupole splitting and full-width at half maximum (FWHM) (Table 2).…”

“…It has been shown that high-temperature phase transformations can lead to the loss of stainless steel's anti-corrosive properties [10]. For example, the commercial CL20ES austenitic steel loses its stainless properties at around 700 • C [11], where intercrystallite rusting appears. The presence of chromium in the bulk does not completely prevent rust formation in the surface layer, as investigated by [12][13][14][15].…”