Abstract
In order to clarify the behavior of hydrogen in ferritic spheroidal graphite cast iron with heavy section, the diffusion coefficient and amount of absorbed hydrogen were measured for specimens cut from a 105 kg spheroidal graphite iron casting, by the use of electrochemical hydrogen permeation method. The results were compared with those on the steel plate of the same alloy contents as the matrix of casting. At room temperature, the diffusion coefficients in cast iron and steel were 1.3 × 10-9m2/s and 2.7 × 10-9m2/s, respectively. The spheroidal graphite cast iron contained more hydrogen than steel, and 80 to 90 vol % of whole hydrogen was diffusible and 10 to 20 vol % was undiffusible. Hydrogen should be stored at interface between graphite nodules and matrix as well as in lattice defects. A gas permeation experiment revealed that the permeation rate of hydrogen in cast iron was lower than that in steel at the temperature range from 403 K to 523 K.
