The Effect of Nickel Plating on the Fatigue Strength of Carbon Steel

Abstract

It is well known that the fatigue strength of machine part is generally reduced when plated with Chromium. But for nickel plating of steel there have yet been but scanty data for ensuring the effective fatigue strength. The author has investigated on that account the effect of nickel plating on the fatigue strength of carbon steel.The fatigue test specimens used in the present experiment were 10mm in diameter, and were made of annealed 0.15%C steel or annealed and quenched-tempered 0.45%C steel. The nickel plating of these fatigue test specimens was carried out in the Watt's type bath, having the composition NiSO4·7H2O 240g/l, NiCl2·6H2O 45g/l, H3BO3·30g/l. Then the current densities were 1.0, 0.7, 0.5A/dm2, and the bath temperature was kept at 25°C.The results obtained can be summarized as follows.1) The higher the fatigue limit is in unplated steel the lower the limit is in nickel plate steel, no matter what the plating condition is.2) The higher the plating current density is the larger the drop of the fatigue limit in nickel plated steel is. It is considered that this is closely connected with the presence of residual tensile stress in the plated layer.3) Moreover, the drop of the fatigue limits in the nickel plated steel is influenced by the plate thickness. The increase of the plate thickness lowers the fatigue limit. This is probably the notch effect due to the rough plate surface and to the crack in the plated metal.