Dear all,
For several month, I'm analysing ferrous artefacts coming from direct
process and that are made from an ore containing high levels of Manganese (a
14th c. forge in the French Pyrenees). The slag inclusions contain up to
30mass% of MnO and Mn is not detectable in the metal (<100ppm). Indeed, the
metal is highly carburised (over eutectoid).
Several authors talk about the carburising role of Mn and, indeed, several
historical zones of producing steel were associated with high Mn ores
(Italian alps, Pyrenees...)
Nevertheless, I have several questions about the exact metallurgical role of
this element in the carburising process during bloomery operating chain.
Indeed, in the thermodynamic conditions of the shaft furnace, the MnO oxide
can not be reduced into metallic Mn. Thus, this element can not play a role
in the metal. Moreover, even if this element were in the iron, it seems that
the influence of Mn on the diffusion coefficient of carbon is not proved.
So, I ask the questions: does anyone study the exact role of manganese on
the carburisation of iron in the direct process. Does Mn play a role indeed?
Can you help me?
Best regards
Philippe Dillmann
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