Effects of Pretreatment Prior to Electroless Ni-P Plating on Fatigue Behavior of SAE 1045 Steel

Electroless Ni-P (EN) plating, as an important group of metallic coatings, employed in a wide range of industrial applications. The current work aims to investigate the effects of pretreatment process before EN plating on fatigue behavior of SAE 1045 steel. The specimens of rotating bending fatigue test were prepared from the steel in two series. A group of samples used in as-polished condition as a base metal and the next group of samples was degreased by Aston and then NaOH 150 gr/lit at room temperature. Subsequently, pickling carried out in an aqueous solution of HCl 30 Vol.% for 3 min. Finnaly, the etching of samples done for 30 seconds in an aqueous solution of HCl 20 Vol.% at 50 °C. In the following, rotating bending fatigue tests carried out on samples. The fatigue fracture surfaces examined by scanning electron microscopy (SEM). Fatigue test results showed an increase in fatigue strength of pretreated samples compared to that of base metal. Reducing the roughness of the surface caused by the pretreatment operation is responsible for this behavior. According to SEM observations, the pretreatment process influences the crack initiation stage, which eventually results in a better performance in fatigue strength.