Internal Friction Influenced by Hydrogen in Super Duplex Stainless Steels

Evaluating the Hydrogen Embrittlement Susceptibility of Aged 2205 Duplex Stainless Steel Containing Brittle Sigma Phase

“…As the hydrogen diffusion coefficient in austenite is lower than the one in ferrite and the aged specimen contained a higher austenite fraction (67% vs 50% 18 ), the overall diffusion speed of the aged sample was largely reduced. [ 15,21–23 ] Moreover, diffusion of hydrogen in σ phase is also slower than in ferrite. [ 22 ] Hydrogen could therefore not reach as deep into the specimen as in the previously studied austenite/ferrite 2205 DSS explaining its lower hydrogen concentration at similar charging times.…”

“…[ 15,21–23 ] Moreover, diffusion of hydrogen in σ phase is also slower than in ferrite. [ 22 ] Hydrogen could therefore not reach as deep into the specimen as in the previously studied austenite/ferrite 2205 DSS explaining its lower hydrogen concentration at similar charging times. The hydrogen concentration at saturation is, however, expected to be higher for the aged 2205 DSS due to the higher austenite fraction characterized by a large hydrogen solubility.…”

“…Only a few references were found by the present authors focusing on HE of DSS with deleterious phases, more specifically σ phase. [ 20–24 ] Iacoviello et al [ 20 ] mentioned that σ phase promotes high embrittlement at low hydrogen quantities. Váñová et al [ 21 ] compared the resistance with HE of an initial and heat‐treated (5 h at 700 °C) 2205 DSS.…”

“…Three reference works involving the joining and welding institute of Osaka in Japan were related to welding processes. [ 22–24 ] With their analysis of internal friction measurements, the authors concluded that a peak could be associated with hydrogen residing in the σ phase. According to geometric calculations, hydrogen atoms moved easily into its tetrahedral interstitial lattice sites.…”

“…According to geometric calculations, hydrogen atoms moved easily into its tetrahedral interstitial lattice sites. [ 22 ] The sigma phase and austenite/sigma phase boundaries were identified to be very prone to crack initiation. [ 23,24 ]…”