Effect of Stress on Hydrogen Attack of Commercial Pure Iron

Mechanical properties of commercial pure iron (JIS:SUY) have been investigated in 9.91 MPa hydrogen and argon at 773 K. Results obtained are as follows: (1) Tensile and creep properties in hydrogen are observed to decrease with proceeding the hydrogen attack in comparison with those in argon. (2) The largest decrease in mechanical properties by hydrogen attack is obtained by constant loading test. (3) An incubation period in hydrogen attack is observed under no loading condition, but not under loading condition by acceleration of decarburization. (4) Internal pressures in bubbles formed by decarburization are estimated by using the equation given by Shewmon, and the effect of stress on the growth of bubbles is discussed.