Evaluation of an electroless nickel interlayer on the fatigue & corrosion strength of chromium-plated AISI 4340 steel

Despite the fact that chromium electrodeposition results in protection agai nst wear and corrosion, combined with chemical resistance and good lubricit y, the reduction in fatigue strength of base metal and environmental requir ements causes one to search for possible alternatives. To improve the fatig ue and corrosion resistance of AISI 4340 steel, an experimental study has b een made for an intermediate electroless nickel layer deposited on base met al. The objective of this study was to analyze the effect of nickel underpl ate on the fatigue and corrosion strength of hard-chromium-plated AISI 4340 steel. Deposition of the conventional wear-resistant hard chromium plating leads to a decrease in mechanical properties of the base metal, especially the fatigue strength. Rotating bending fatigue tests results indicate bett er performance for conventional hard chromium plating. Good corrosion resis tance in salt fog exposure was obtained for the accelerated hard chromium p lating. Experimental data showed higher fatigue and corrosion resistance fo r samples prepared with accelerated hard chromium plate over electroless ni ckel plate, when compared with samples without electroless nickel underplat e.