Effects of Carbide Forming Elements on Hydrogen Attack and Embrittlement in 2 1/4 Cr-1Mo Steel

Improvement in resistance to disbonding of stainless steel-overlayed 2 1/4Cr-1Mo steels.

“…(2) The composition, morphology and distribu- (3) A good resistance of the V-modifled steel to disbonding is attributed to low diffusion coefficient of 12) hydrogen and high solubility of hydrogen at room temperature and consequently low concentration of hydrogen at the interface between the base metal and 13) the welded overlay.…”

A Comprehensive Examination of High-Temperature Hydrogen Attack—A Review of over a Century of Investigations

“…• Although as a general statement, it has been reported that higher impurity levels (and larger grains) make the grain boundaries more prone to HTHA cracking (Ref 68), the actual effect of impurities on HTHA resistance appears to be complicated and not completely/clearly determined.Rosenthal et al (Ref 100) reported that impurities such as P and S, which would segregate at grain boundaries, can have a retarding effect in grain-boundary fissuring by HTHA in carbon steel. They suspected that the retarding effect was due to the reduction of grain-boundary energy and reduction of grain-boundary diffusion.Sakai et al (Ref 88,94,101,102) investigated the effects of the impurity elements phosphorous, tin, arsenic and antimony on HTHA bubble formation and growth in Cr-Mo steels. They found that an addition of 0.016 wt.% Sn or 0.016 wt.% Sb increased the bubble density (by a factor of 2-3) in a 2.25Cr-1Mo steel, whereas an addition of 0.016 wt.% P or 0.017% As decreased the bubble density (by a factor of 0.5-0.75).…”