Hydrogen Induced Hardening and Embrittlement of Vanadium Alloys

Tensile properties were measured for several vanadium base alloys with or without hydrogen charging, such as V-4Ti, V-6W-1Ti, V-4Cr-4Ti and that from the National Institute of Fusion Science in Japan. Their hydrogen embrittlement behaviors were studied. Results show that the vanadium alloys have high hydrogen absorption rate, which is increased by the Ti alloying element. Hydrogen induced hardening is found to be a solid solution one and the hardening rate could be decreased by Ti addition, which accounts for the higher resistance of the Ti-bearing alloys as compared to those without Ti. Increasing oxygen concentration would enhance the embrittlement. In that case low strength alloy showed better. The critical hydrogen concentration required to embrittle the alloy for V-4Cr-4Ti with O of 200~400 μg/g is about 300 μg/g, but lower than 50 μg/g when O content increases to 700 μg/g.