Inferences of Baking Time on Hydrogen Embrittlement for High Strength Steel Treated with Various Zinc Based Electroplating

The hydrogen embrittlement of SK85 high-strength steel sheets was evaluated using a three-point bending test. The effect of electroplating the metal with zinc-based coatings on hydrogen embrittlement was examined by baking treatment of differently electroplated steel specimens. After electroplating, all the specimens underwent hydrogen embrittlement, promoted by hydrogen incorporation into the metal frame, owing to the reduction of hydrogen ions during electroplating. The hydrogen embrittlement of both zinc-and zinc-SiO2-electroplated SK85 steel continued after baking for 24 hours at 473 K, but that of zinc-nickel-and zinc-nickel-SiO2-electroplated SK85 steel ceased. Furthermore, TDA revealed that the trapped hydrogen could be released from steel at approximately 473 K. However, after baking, hydrogen embrittlement did not completely disappear, and we suggest that the formation of hydrogen vacancy clusters also accounts for this fracture phenomenon. The hydrogen incorporated into steel during electroplating led to the formation of hydrogen vacancy clusters, which allowed the formation of embrittlement. However, zinc and zinc-SiO2 films were not permeable enough to release these voids; while the peculiar zinc–nickel and zinc-nickel-SiO2 film structure enabled the hydrogen vacancy clusters to diffuse from the substrate.

Hydrogen Embrittlement Characteristics in Irradiated Stainless Steel

Hydrogen is produced in nuclear reactors as a by-product of the corrosion reaction between the pressure vessel and the cooling water, where hydrogen produced may enter the metal in atomic form. During operation a reactor vessel is exposed to avalanche of neutron irradiation fluxes, in addition to corrosion from cooling water. A novel cluster dynamics model that accounts for off-stoichiometry of clusters and matrix was developed and applied to investigate the clustering behavior of Hydrogen-vacancy and Hydrogen-interstitial clusters in proton irradiated stainless steel has been developed. The differences in point defect migration energies and binding energy of H to lattice defects, makes it possible to have vacancy and interstitial clusters having compositions different from those of pure iron. The model predicts populations of Defect-Hydrogen complexes in iron. The model is applied to the early stage formation of voids and dislocation loops in stainless steel in the presence of atomic hydrogen. This study investigates the effect of irradiation dose and temperature on the concentration of vacancy-Hydrogen (VmHn) and Intersitial Fe-H (FemHn) complexes on bulk α-Iron. The re