Vacuum effect on the plastic zone around a fatigue crack in armco iron

Studied was the character of plastic deformation and the plastic zone size around a fatigue crack in armco iron deformed in air and in vacuum in low- and high-cycle loading ranges. The relationship between the fatigue crack growth rate and plastic zone size is expressed by a power function, with its coefficient being dependent on the medium. The lower fatigue crack growth rate has been shown to result in a larger value of the macroscopic zone in vacuum compared to that in air. Suggestions have been made about the reasons of this effect