Study the effect of the nickel interlayer on the hydrogen embrittlement of the Cr-Si spring steel electroplated with Zn-Ni alloy

In this paper, the hydrogen embrittlement of the high strength Cr-Si spring steel with after Zn-12%Ni electroplating, have been evaluated. Slow strain rate test with 3.34 × 10-6 sec-1 strain rate was performed, and the hydrogen embrittlement index of the different samples was calculated. The effect of baking after plating and also the effect of applying a nickel interlayer by electroless method, is examined by using the weibull statistical model. The results showed that alloying Zn with nickel considerably reduce the diffusion of hydrogen on the substrate steel structure. So that it increases the average failure time of samples from 4.9 hours for pure Zn to 8.7 hours for Zn-Ni. By applying nickel interlayer, the failure time increased to 11.15 hour. Baking after the electroplating of Zn-Ni samples without interlayer, leaded to an increase in the failure time to 10.15 hours. While baking in samples containing nickel interlayer, showed the opposite effect, reducing the failure time to 8.15 hours.