Effect of plastic deformation on hydrogen embrittlement sensitivity and strength of 2.25Cr1Mo0.25V steel by synchronous hydrogen charging

The hydrogenation reactor is an important equipment in petrochemical industry, and it has been produced by many processes such as plate rolling and welding. It served in high temperature, high pressure in hydrogen environment, and faced the risk of hydrogen embrittlement in the stages of operation and downtime cooling. Moreover, plastic deformation is inevitable in the manufacturing process of hydrogenation reactor, and influence mechanical properties and hydrogen resistance of materials. 2.25Cr1Mo0.25V is widely used in the hydrogenation reactor, so it is important to discuss how the plastic deformation affect hydrogen embrittlement sensitivity. In this paper, the effect of plastic deformation on hydrogen embrittlement sensitivity and strength of 2.25Cr1Mo0.25V steel was investigated by slow strain rate tensile test coupled with electrochemical hydrogen pre-charging and synchronous charging experimental method. The experimental method was better than the common method which performs tensile test after hydrogen charging. Results show that hydrogen embrittlement sensitivity increases with the growth of plastic deformation. When the plastic deformation reached the necking area, the hydrogen embrittlement sensitivity decreases with the growth of plastic deformation. In addition, hydrogen significantly reduced the breaking strength of this steel, while the plastic deformation only increased the yield strength of this steel. The fracture morphology of tensile specimens indicated that the hydrogen embrittlement caused by electrochemical charging was very obvious, and the trend of hydrogen embrittlement degree of the fracture was basically consistent with the result of mechanical experiment. The mechanical properties and fracture micro-morphology of specimens without hydrogen and specimens with electrochemically irreversible hydrogen were compared, it can be obtained that the effect of electrochemically irreversible hydrogen on mechanical properties was negligible.