Abstract
Tensile tests and Charpy impact tests have been performed on pure cast Mg with hydrogen concentrations of 16–35 mass ppm, where hydrogen was mainly segregated at triple junction of grain boundaries. Tensile properties were not affected by the hydrogen concentration, but crack formation at grain boundaries was enhanced by an increase in hydrogen concentration. The Charpy impact tests showed that the Mg with a higher hydrogen concentration exhibited a higher ductile-brittle transition temperature and that the temperature dependence of the Charpy impact energy was in good agreement with that of fractography. Thus, the segregation of hydrogen at grain boundaries likely induced the intergranular fracture of Mg.
