DIFFUSIBLE HYDROGEN BEHAVIOR IN PRE-STRAINED HIGH-STRENGTH STEEL

Diffusible hydrogen behavior in pre-strained high strength steel was investigated by use of a newly developed hydrogen content determining method for better understanding of delayed fracture. Pre-straining up to 4.2% formed a new hydrogen trapping site in the steel. When hydrogenerated in a 0.1N HCl solution, hydrogen content in the steel increased with the amount of pre-straining. The trapping site resulted from pre -straining was removed by aging at 200 degrees C. During the hydrogenation of the 4.2% pre-strained specimen, hydrogen content in the steel increase in accordance with Fick's law. The decrease of hydrogen content in the specimen pre-strained, hydrogenated, then held at room temperature cannot be explained by a single diffusion rate. This phenomenon can be better explained by assuming that hydrogen in the lattice and trapping sites diffuse independently without showing local equilibrium.