No abstract

The precipitation of intermetallics in a 26Cr-4Mo-2Ni (Ti + Nb) super ferritic stainless steel during aging at 800°C was investigated. Optical, scanning electron and transmission electron microscopes and X-ray diffractometer were used to characterize the microstructure. Results show that the χ phase formed in 5 min and almost disappeared within 24 h. The σ phase began to form at grain boundaries when aged for 30 min and its amount increased with prolonged aging. After 24 h, the σ phase covered the grain boundaries and grew into the grain interiors. The Laves phase was found to form within 30 min.