Precipitation of M23C6 type carbide on twin boundaries in austenitic stainless steels

摘要: An electron microscopy investigation was made of M/sub 23/C /sub 6/ carbide precipitation in two kinds austenitic stainless steels, A (AISI 316L type alloy) and B (DIN 4981 alloy). The specimens were water quenched from high annealing temperatures aged at 800 degrees C. In particular, the process on twin boundaries carefully examined. 23/C/sub carbides observed to form first grain incoherent as small precipitates. formation lamellar precipitates then proceeded coherent region adjacent boundaries. morphology found depend strongly stress field. growth appears be a consequence planar distortion {111} planes. geometrical is characterized by {111}- {110}-type interfaces. general, interfaces predominant. One exceptional mode observed, however, which precipitate formed around an undissolved residual NbC particle Alloy B.