Tensile tests under cathodic charging were carried out on sensitized Inconel 600 alloy poly crystals. The maximum sensitivity of hydrogen embrittlement (HE) was recognized on the specimen sensitized at 973K, and the specimen fractured with intercrystalline mode. The effect of cold working before the sensitized treatment was recognized in the sensitivity of HE and the morphology of fractured surface. When the prestrain increased, the sensitivity of HE was decreased and the fracture morphology changed from intercrystalline to transgarnular. On the single crystal specimen, no effect was recognized in both the sensitized temperature and the cold working before sensitization. Intercrystalline and transcrystalline cracks occurred on the surface of polycrystal specimen by hydrogen charging under no loading condition. Also, the cracks on the surface of single crystal specimen were produced along {001} planes hydrogen under the same condition.
