Comparison of tensile and impact behavior of carbon steel in H2S environments

• Tensile and impact behavior of the steel had different change law with H2S pressure.
• Charpy absorbed energy exhibited no obvious change with increasing H2S pressure.
• Fractography showed mixed ductile–brittle rupture for the corroded mechanical samples.
• Hydrogen has a profound effect on the tensile and impact behavior of steel.
• A probable mechanism is proposed to interpret the tensile and impact results.

The present research reports the effect of hydrogen sulfide pressure on the tensile and impact behavior of carbon steel. Hydrogen content measurement was conducted due to the relationship between hydrogen and mechanical behavior. A remarkable increase in the relative tensile strength and plasticity loss was observed as hydrogen sulfide pressure increased. However, the Charpy absorbed energy showed no obvious change with increase of H2S pressure from 0.1 MPa to 1.6 MPa, even though a significant decrease compared to that of as-received steel. Combined with the results of hydrogen content measurement, it was found that hydrogen has a profound effect on the tensile and impact behavior of steel. Fractography of the corroded tensile and impact specimens exhibited mixed ductile–brittle rupture. In addition, the brittle zone on the fracture surface increased for corroded tensile specimens and showed nearly similar area fraction for corroded impact specimens as H2S pressure increased. A probable mechanism is proposed to interpret the difference in the tensile and impact results.