CARBIDES ANALYSIS OF THE HIGH STRENGTH AND LOW DENSITY Fe-Mn-Al-Si STEELS

LOW DENSITY Fe-Mn-Al-Si STEELS Th e work presents the results of investigations into the structure and phase composition of newly developed high manganese steels of the X98MnAlSiNbTi24-11 and X105MnAlSi24-11 type.The average density of such steels is 6.67 g/cm 3 , which is 15% lower as compared to typical structural steels.An analysis of phase composition and structure allows to conclude that the investigated steels feature an austenitic γ-Fe(Mn,Al,C) structure with uniformly distributed and elongated α-Fe(Mn,Al) ferrite grains on the boundaries of austenite grains and carbides.Examinations by diffraction of back scattered electrons (EBSD) allow to conclude that high-angle boundaries dominate in such steels, having significant influence on mechanical properties.Three types of carbides with differentiated chemical composition and size were identified in steel X98MnAlSiNbTi24-11 with scanning and transmission electron microscopy.κ-(Fe,Mn) 3 AlC carbides, having a regular, face-centered cubic lattice (fcc), were identified in austenite.Transmission electron microscopy examinations have enabled to identify M 7 C 3 -type carbide in ferrite.Nb-and Ti-based complex carbides were identified in steel X98MnAlSiNbTi24-11, both, in ferrite and austenite.(NbTi)C 2 carbide precipitates were confirmed in an X-ray qualitative phase analysis.The size of the above-mentioned carbides is within several to several dozens of μm.An X-ray qualitative phase analysis has confirmed the precipitates of M 7 C 3 carbides in both steels.