Positron annihilation study of the effect of hydrogen during the plastic deformation of a steel

Positron lifetime measurements were conducted on spheroidized low carbon steel (AISI 1009) deformed without hydrogen, hydrogen charged after deformation and hydrogen charged during deformation. These were measured as a function of tensile strain at a constant value of hydrogen input fugacity (250 MN m −2). Decoration of dislocation sites with hydrogen reduced the relative intensity of the short-lifetime component. Deformation with hydrogen in the steel increased the relative intensity of the long-lifetime component, signifying an increase in concentration of vacancy agglomerates or microvoids.