Abstract
An investigation has been carried out to find the effect of diffusion treatment on the fatigue strength of nickel plated steel.
The results obtained are summarized as follows;
(1) S-N curves indicated that the fatigue strength of the plated steel was slightly lower than that of the bare steel but the fatigue life of the diffusion treated steel was longer.
(2) Macroscopic observations on the plated steel revealed that the fatigue crack nucleated under the plated layer, while in the diffusion treated steel the crack nucleation occurred at the surface.
(3) By fractographic observations, the stage II type fatigue striation was noticed at the fracture surface of the bare steel, whereas the stage I type patterns, flat and grain boundary facets of the stage I type patterns were noticed in the diffusion treated steel.
(4) A possible reason for the fatigue life recovery of diffusion treated steel is considered that the stage I period is prolonged by the effect of the solid-solution strengthening by inter-diffusion of iron and nickel.
