It is known that strain aging affects a material’s mechanical behavior, complicating plastic deformation and resulting in embrittlement. In the current study, the mechanical behavior of steel specimens was investigated after different pre-treatments (low-temperature tempering and hydrogen charging followed by low-temperature tempering) and compared with that of the untreated one. The pipe steel API 5L X52 strength grade was studied. It was revealed that strain aging occurred in some local areas with increased stresses induced by hydrogen charging. It resulted in a significant reduction in fracture toughness and resistance to stress corrosion cracking of pipe steel. The effect of strain aging on tensile properties and the Charpy notched toughness of the steel was minor. It was demonstrated that hydrogen absorbed by a metal can cause embrittlement through strain aging mechanism, primarily at the grain boundaries, which are the dominant sites of hydrogen transport.