Hydrogen embrittlement of stainless steel overlay materials for hydrogenators

Abstract An investigation was carried out of the effect of hydrogen absorption on the tensile ductility of composite specimens representing stainless steel weld overlays on low alloy steel substrates as used in the fabrication of hydrogenators. Specimens of the two stainless steels (AISI 309 and 347) involved in hydrogen cracking were also fractured in tension at strain rates between 5.9 × 10 −6 and 1.5 × 10 −3 s −1 after thermal charging with hydrogen. Results indicated that only the 347 samples suffered significant embrittlement by hydrogen and the original ductility could be restored by subsequent annealing for a time and temperature determined by the hydrogen diffusivity.