Nitriding of ternary Fe–Cr–Mo alloys; role of the Cr/Mo-ratio

Continuous and discontinuous precipitation in Fe-1 at.%Cr-1 at.%Mo alloy upon nitriding; crystal structure and composition of ternary nitrides

“…Earlier atom probe field ion microscopy (APFIM) studies of nitrided Fe-Mo alloys [14], [35] also suggested the presence of considerable amounts of Fe in Mo-nitrides 1 , whereas a study of nitrided Fe-Mo alloys based on Mössbauer spectroscopy [36] could not at all detect Fe in the nitrides. Furthermore, the aberrations by LME affect the observed shape of the precipitates: the width of the platelets appears thicker in Fig investigation by our group of a series of Fe-Cr-Mo alloys of varying Cr/Mo-ratio, the Ncontent in the nitrided zone was found to comply with the above described rule for the composition of the mixed CP nitrides [39]. This result is a strong indication that indeed no significant amount of Fe is incorporated in these nitrides.…”

Alloying Element Nitride Development in Ferritic Fe-Based Materials Upon Nitriding: A Review

“…The consequence of the formation of the coarsened microstructure by both types of discontinuous reactions is a considerable loss of hardness and residual stresses in these regions, see e.g., Ref 24,27,48.…”

“…The large volumetric misfit of nitride precipitates and ferrite matrix (see Table 1) leads to a considerable tendency for the nitrided zone to expand. However, as the nitride zone is constrained by its adherence to the (rigid) unnitrided core, high compressive (residual) macrostress is present parallel to the surface in the surface adjacent region ( Ref 24,48,78,79). Upon relaxation of the nitrided zone, e.g., by DC (Ref 24), the compressive macrostress at the surface relaxes, and may even turn to a tensile macrostress, if the relaxed region is ''on top'' of a ''freshly nitrided'' region [see Fig.…”

Optimization, by Means of a Design of Experiments, of Heat Processes to Increase the Erosive Wear Resistance of White Hypoeutectic Cast Irons Alloyed with Cr and Mo

“…This precipitation may occur during high temperature tempering [14]. In steels, a thermochemical nitriding treatment produces surface hardening via the formation of subnitrides of Cr, V, Mo, and Al in the tempered martensite matrix [29,30]. However, there are no previous reports of the nitriding of high chromium white cast irons.…”

“…However, there are no previous reports of the nitriding of high chromium white cast irons. In the case of steels belonging to the Fe-Cr-Mo system, the type of (CrMo) x N y nitrides will depend on the Cr/Mo ratio [30].…”