Hydrogen induced ductility loss of hydrogen-charged and hydrogen-releasing 304L austenitic stainless steel

摘要

The mechanical properties and fracture behaviors of type 304L austenitic stainless steel after hydrogen charging and hydrogen releasing are investigated by tensile tests. Hydrogen was introduced into 304L plate specimens by electrochemical hydrogen charging. When the charging procedure completed, some specimens were tensile immediately to fracture and some were aged to release the hydrogen out of the specimens and then were also tensile to fracture. The resulting tensile properties of hydrogen-charged and hydrogenreleasing specimens were evaluated and compared. The results reveal ductility loss for hydrogen-charging specimens and it is dependent upon the charging current density. Ductility loss increases as the current density increasing. SEM morphologies showed that the edge zone of the fracture surfaces changed from ductile fracture before hydrogen charging to embrittlement fracture after hydrogen charging. After hydrogen releasing, the specimens can recover a certain degree but not their entire original ductility due to that some irreversible damage had developed in the specimens during hydrogen-releasing, the culprit was the high tensile stress generated during hydrogen releasing.