EFFECT OF HEAT-TREATMENT ON THE MICROSTRUCTURE OF A HIGH-NITROGEN 12-PERCENT CHROMIUM MARTENSITIC STEEL

The present investigation aims at a better understanding of the aging microstructure of a high-nitrogen (0.11%N) 12%Cr steel with a view of optimizing the mechanical properties. The precipitation behaviour is r ather complex. The dissolution of the numerous kinds of precipitates a nd their precipitation are studied by transmission electron microscopy for a wide temperature treatment domain between 200 and 1150-degrees- C. The microstructural evolutions are correlated to hardness measureme nts with the outcome of the determination of heat treatment parameters required to achieve the maximum of secondary hardening.