MORPHOLOGY OF CARBIDE AND NITRIDE PRECIPITATES IN FERRITIC STAINLESS CHROMIUM STEELS

In the finished state, ferritic nonstabilized NIROSTA stainless steels display a ferrite microstructure with fine Me//2//3Cr//6 precipitates which are formed as a result of soft-annealing of hot-rolled strip or final annealing of cold-rolled strip. Stabilized steels with titanium or niobium additions contain difficult-to-dissolve coarse carbide or nitride precipitates which are mechanically destroyed during hot or cold forming. Slightly soluble carbides are precipitated in finely dispersed form after hot forming and during final annealing. The morphology of the precipitates in the as-cast state and after forming operations and heat treatment are shown in scanning electron micrographs and photomicrographs.