OBSERVATION OF TRAPPING SITES OF HYDROGEN AND DEUTERIUM IN HIGH-STRENGTH STEELS WITH SECONDARY-ION MASS-SPECTROMETRY

Hydrogen and deuterium trapping sites in high-strength steels have bee n observed by secondary ion mass spectrometry (SIMS). High-strength st eels with 1400 MPa tensile strength are loaded and dipped in D2O and 2 0% NH4SCN solution at 323 K to occlude hydrogen and deuterium. As a re sult, the depth profiles by SIMS show the presence of deuterium means hydrogen trapping site occluded during delayed fracture test. Secondar y ion-image analysis by SIMS has made possible to observe hydrogen and deuterium trapping sites in high-strength steels. Hydrogen tends to a ccumulate at grain boundaries, in segregation bands, and in inclusions . Line scans by SIMS show that the concentration of hydrogen is 7.8 ti mes as high at grain boundaries as in the matrix, 5.0 times as high in the segregation bands, and 11 times as high in the inclusions. Hydrog en trapping sites at grain boundaries can be observed by measuring aft er the delayed fracture test as soon as possible.