Abstract: The effect of female screw rolling strengthening on the fatigue property of 300M superhigh steel has been investigated. The stregthening mechanism was studied also by means of X ray stress analyses SEM and TEM. It was shown that by screw rolling strengthening the fatigue strength limitation of the specimen was improved from σ 0 1 =250MPa to σ 0 1 =448MPa. The high macroscopic compressive residual stress, the increase in dislocation density in the strengthened layer and the decrease in the screw surface roughness were the major factors leading to the enhanced fatigue strength.

Key words: high strength steels, threads, residual stress