Hydrogen-enhanced cracking of 2205 duplex stainless steel

Tensile and fatigue crack growth tests of 2205 duplex stainless steel (DSS) were performed in laboratory air, gaseous hydrogen at 0.2 MPa and saturated H 2 S solution. The longitudinal specimen showed a lesser degradation of tensile properties than the transverse ones in saturated H 2 S solution. The orientation of specimens with respect to rolling direction had little influence on the fatigue crack growth rate (FCGR) of the alloy in air. Furthermore, 2205 duplex stainless steel was susceptible to hydrogen-enhanced fatigue crack growth. Transmission electron micrographs, in addition to X-ray diffraction, revealed that the strain-induced austenite to martensite transformation occurred near the crack surface within a rather narrow depth. Fatigue fractography of the specimens tested in air showed mainly transgranular fatigue fracture with a small amount of flat facet fracture. Furthermore, extensive quasi-cleavage fracture of 2205 duplex stainless steel was associated with the hydrogen-enhanced crack growth.