The effect of surface treatment on the fatigue strength of N26T low-magnetic phase work-hardenable steel

1. Steel strengthened by phase work-hardening is distinguished by a ratio of fatigue limit to tensile strength (σ−1/σu=0.55−0.60) significantly greater than that of dispersion hardening steel. 2. The surface treatment method (grinding, turning, surface plastic deformation to a definite intensity) does not have a significant effect on the fatigue strength of N26T steel strengthened by phase work-hardening. 3. Combined strengthening of phase work-hardenable steel by surface plastic deformation, which causes the formation of 15–25% α phase on the surface, and subsequent aging at 350–400°C is an effective means of increasing life. The use of this method makes it possible to increase the fatigue limit by 20% for uniform cross section samples and by 200% for those with a notch. 4. The increase in the fatigue limit with the use of combined strengthening (surface plastic deformation and aging) is related to the increase in the strength of the surface layers as a result of the increase in the dislocation density and fixing of them by the particles of Ni3Ti precipitated in aging and also to the decrease in peak microstresses.