Hydrogen embrittlement and fracture mode of EUROFER 97 ferritic-martensitic steel

The hydrogen embrittlement of EUROFER 97 ferritic-martensitic steel promotes a change from ductile to brittle trans- and inter-granular fracture during fracture toughness testing. The brittle fracture is controlled by hydrogen content in the range of 2–4 wppm and strongly depends on the extent of hydrogen saturated trapping sites. The same hydrogen concentration in base and weld metals manifests itself by different extents of brittle fracture, higher in base metal and lower in weld metal as a result of a different number and saturation of trapping sites. The extent of brittle fracture on surface specimens decreases along the hydrogen concentration gradient from the crack tip and with increasing testing temperature.

► Hydrogen effects the fracture toughness of base and weld metal of EUROFER 97 RAFM steel.
► The J0.2 integral values decrease depending on the hydrogen content in the range of 0–4 wppm.
► With increased temperature in the range of 25 °C–120 °C the brittle fracture mode decreases.
► The extent of brittle trans- and inter-granular fracture decreases in the direction of crack propagation.
► Results of this work would help of structural integrity assessment of ITER test blanket module components.