1996 Volume 82 Issue 4 Pages 327-332
Internal friction in the hydrogen-charged 18Ni maraging steel was measured as a function of temperature from 140 to 350 K at a frequency of about 600 Hz. A characteristic internal friction peak was observed at about 240 K after hydrogen charging under the as-aged condition. The height of the internal friction peak increased with increasing hydrogen content, but appeared to be saturated at a certain level of hydrogen content. The saturated value of the peak height increased with the degree of cold work, that is, with increasing reduction of area for cold rolling. Thus, this internal friction peak was identified as the cold-work peak based on the hydrogen-dislocation interaction in maraging steel, as has been well known in pure iron. The peak can therefore be interpreted to be caused by the hydrogen atoms trapped at dislocations. The hydrogen cold-work peak in the underaged specimen was found to shift to lower temperature compared with that in the optimum aged specimen. This difference in the peak temperature seems to be attributed to the change in the binding energy between hydrogen atoms and dislocations.
