AN INVESTIGATION ON FATIGUE AND FATIGUE CORROSION BEHAVIOR OF Cr-Si SPRING STEEL AFTER Zn-Ni ELECTROPLATING USING WEIBULL STATISTICAL MODEL

Compression springs were prepared from Cr-Si high strength spring steel and coated with pure Zn and Zn- Ni by electroplating process. The effect of baking after electroplating as well as applying an electroless nickel interlayer on the fatigue and fatigue corrosion of the springs was investigated. The results were analyzed using weibull statistical model. A considerable improvement (8%) in fatigue life of the electroplated springs with Zn-Ni was observed in the presence of Ni interlayer. In addition, baking of these electroplated springs improved fatigue life by 4%. The fatigue life under salt spraying conditions, however, has demonstrated remarkable reduction by 40%, 34% and 30% for Zn-Ni plating, backed and unbaked Zn-Ni plating containing Ni interlayer, respectively.