When ferritic stainless steels are exposed to the temperature range of 700-800°C, embrittlement takes place, which is known as the -phase embrittlement. In the present study, axial fatigue tests were conducted using a high-chromium ferritic stainless steel, type 447 with the chromium content of 30.7%, which was aged at 750°C for 150h and 300h, and the effect of -phase embrittlement on the fatigue behaviour was discussed. Vickers hardness increased significantly by aging due to the precipitation

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... of hard -phase. The aged specimens exhibited much lower fatigue strengths than the un-aged one, where fatigue strength decreased with increasing aging time. The precipitation of brittle -phase reduced the crack initiation and growth resistances, resulting in the lower fatigue strengths of the aged specimens.