The effect of electrical hydrogen charging on the strength of 316 stainless steel

The effect of electrical hydrogen charging on the strength of 316 stainless steel specimens has been investigated in tensile tests at 223 K, and the increase of yield stress and the decrease of total elongation were observed. These tendencies increase with increasing hydrogen content of the specimens. This is considered to be due to hydrogen-induced phase transformation from γ (fcc) to ε (bcc), α (bcc), which was confirmed by X-ray diffraction method. Hydrogen concentration was determined by elastic recoil detection (ERD) method, the maximum of which reached 40% near the surface region. Positron annihilation lifetime was also measured after electrical hydrogen charging and a longer lifetime of about 300 ps was observed, which suggests the formation of microvoids in the specimens