Hydrogen embrittlement of 2205 duplex stainless steel in in-situ tensile tests

Abstract

Extensive use of hydrogen derived from renewable energy sources is currently limited by a lack of effective storage and transport solutions. Steels able to withstand hydrogen gas environments at high pressure are needed for the manufacture of safe and reliable storage vessels and pipes. The mechanical behavior of 2205 duplex stainless steel (54 % ferrite – 46 % austenite) was studied through tensile tests performed on smooth and notched specimens, submitted at the same time to electrochemical hydrogen charging. Hydrogen uptake was controlled by means of electrochemical charging and measured using a LECO DH603 hydrogen analyzer. The roles of different experimental parameters such as applied current density (from 0.02 to 0.5 mA/cm2), electrolyte (1 M H2SO4 + As2O3 or 3 % NaCl solution), and applied displacement rate (from 0.002 to 0.4 mm/min) were also evaluated. Finally, the fracture surfaces of all the tested specimens were analyzed under a scanning electron microscope (SEM) and the prevalent failure micromechanisms were analysed.Hydrogen embrittlement indexes in both smooth and notched specimens increase as hydrogen content in the electrolyte, current density increase and displacement rate decreases. In all the in-situ hydrogen charged tests, two different regions were observed in the fracture surfaces, a brittle region on the outer region of the specimen, enriched with hydrogen in the course of the test and a ductile region in the center of the specimen.