Evaluation of hydrogen entry into high strength steel under atmospheric corrosion

Hydrogen entry into high strength steels by atmospheric corrosion has been investigated to evaluate their susceptibility to hydrogen embrittlement. High strength steels were corroded by dry/wet cyclic corrosion after NaCl deposition. The maximum diffusible hydrogen concentration around the surface was successfully obtained by means of thermal desorption analysis after keeping the specimens at high humidity to reproduce enhanced hydrogen entry influenced by the rust layer and to homogenize the hydrogen distribution. Despite decrease in corrosion rate, hydrogen content in specimens did not decrease. Decrease of pH in inner rust layer is responsible for the enhanced hydrogen entry into steel.