Mössbauer measurements backscattering technique (CXMS) of laser irradiated cold forming tool steel (X210CR12)

Conversion x-ray Mössbauer measurements (CXMS) in backscattering technique are performed on a commercial cold forming tool steel (X210Cr12), subjected to single-pass laser irradiation. The structure of the affected layer is examined for laser powers ranging from 2700 W to 3050 W at different depths. The results of the spectra analysis are discussed in connection with Vickers hardness and metallographic data. If a complete molten layer is quenched, a high carbon content austenite is retained down to room temperature. This phase is mixed with some low carbon martensite and (Cr 0.5 Fe 0.5)> C₃ carbide. The effects of carbon diffusion from the coating medium into the bulk are discussed. It is demonstrated that Mössbauer spectroscopy is a sensitive tool for phase analysis, including information about phase formation, and for delimiting the range of the quenched molten layer after laser treatment. It is thus a promising technique in this special kind of steel engineering.