Microstructure characterization of two Z-phase strengthened 12%chromium steels

Paper in proceeding, 2014

The microstructure of two Z-phase strengthened steels was characterized in different heat treatment conditions, as-tempered and after 1000 hours ageing at 650°C. A high Cr content together with Ta and N additions were used to stimulate the formation of a fine distribution of Z-phase as strengthening particles in both alloys. Atom probe tomography, transmission electron microscopy, and scanning electron microscopy were employed for a detailed characterization of the microstructure. The A1 steel contained very little carbon, which resulted in a fast transformation from MX to Z-phase. In the A2 steel that contained a higher carbon content and an addition of Cu, the MX to Z-phase transformation was slower. The Cu addition to the A2 steel improved Laves-phase distribution and morphology.