from the conferences organized by TANGER Ltd.
Carbon diffusion was studied in temperature interval 573 - 1073 K in carbon-supersaturated surface layer of 9Cr–1Mo steel P91 and in model Fe-15Cr binary alloy. Extremely low carbon diffusion coefficient D (by 3 orders of magnitude lower than the value Deq in material with equilibrium carbon concentration) was observed in carburized surface region of Fe-15Cr. Similar results were obtained for P91 above the temperature Tn ~ 800 K. However, below Tn, the values of D measured in P91 increased and approached the value of Deq. It seems that the non-Arrhenius behaviour of P91 steel around Tn may be ascribed to the α → α + α’ phase decomposition. Possible effect of nitrogen upon the low-temperature increase in D in P91 steel was excluded.
Keywords: Diffusion, Carbon, phase decomposition, Carbon-supersaturation, Cr-Mo steels© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.