3519 水素ステーション蓄圧器用低合金鋼SCM435の引張強度特性に及ぼす水素の影響(S20-4 水素環境での静的強度と破壊じん性,S20 材料強度特性に及ぼす水素の影響)  [in Japanese] 3519 Effect of Hydrogen on Tensile Strength of SCM435 Steel used for Storage Cylinder in Hydrogen Station  [in Japanese]

We investigated the effect of hydrogen on tensile properties of SCM435 steel used for hydrogen storage cylinders. The two types of tensile specimens in the longitudinal and transverse directions were machined out from the SCM435 steel cylinder. The specimens were immersed in an aqueous solution of NH_4SCN and then charged with hydrogen. The hydrogen content in hydrogen-charged specimens was 0.14ppm and 0.93ppm. The tensile strength of hydrogen-charged and uncharged specimens was 930MPa. Increase in hydrogen content reduced the reduction of area from 72% to 44% for longitudinal specimens and from 63% to 44% for transverse specimens. The observation of fracture surfaces suggested that the mechanism of the hydrogen embrittlement was based on the hydrogen enhanced localized plasticity rather than the lattice decohesion.