Zinc-nickel alloys received considerable interest recently, since these coatings showed some
advantages such as a good resistance to white and red rust, high plating rates and acceptation in the market. In
this study the effects of zinc-nickel coatings electroplated on AISI 4340 high strength steel were analysed on
rotating bending and axial fatigue strength, corrosion and adhesion resistance. Compressive residual stress
field was measured by a X-ray tensometry prior to fatigue tests. Optical microscopy images showed coating
thicknesses, adhesion and the existence of an uniform coverage of nearly all substrates. The fractured fatigue
specimens were investigated using a scanning electron microscope. Three different zinc-nickel coating
thicknesses were tested and comparison with rotating bending fatigue data from specimens cadmium
electroplated and heat treated at 190°C for 3, 8 and 24 hours to avoid the diffusion of hydrogen in the
substrate, was performed. Experimental results showed effect of coatings on the AISI 4340 steel behaviour
when submitted to fatigue testing and the existence of coating thickness influence on the fatigue strength.
