The hydrogen assisted crack initiation susceptibility of 5-Ni-Cr-Mo-V (MIL-S-24371A) quenched and tempered steel plate, weldment, and Gleeble thermal cycled materials representative of tempered and untempered weld metal was investigated in 3.5% NaCl solution. The conjoint role of steady state diffusible hydrogen content and maximum principal stress was quantitatively characterized by: (1) Devanathan-Stachurski hydrogen permeation tests, and (2) slow strain rate tests conducted under various cathodic protection levels.
For the four material conditions studied, the threshold maximum principal stress decreased with increasing hydrogen concentration. The base plate was less susceptible to hydrogen assisted crack initiation than the weld metal and thermal cycled weld metals. The tempered and untempered thermal cycled weld materials defined the upper and lower bounds of the aswelded material cracking susceptibility respectively.