Chrome Plating, Electroless Nickel and Fatigue Life

[Schuyler]

It's my understanding chrome plating reduces the fatigue properties of the plated substrate. Typically by how much (%)? What causes the reduction? Is the reduction for electroless nickel plating as much as hard chrome plating? If available, please provide data.

 

[TVP]

Hard chromium reduces the fatigue strength of the base material because the coating is highly cracked. During the electroplating process, the deposited coating is under high residual tensile stress, and micro-cracks form to relieve this stress. These defects in the coating serve as initial sites for fatigue cracks to develop and initiate into the substrate.

Electroless nickel coatings typically do not have this highly cracked network in the deposited coating. Fatigue reduction will be negligle compared to the hard chromium plating.

FYI, the fatigue reduction does not apply when fretting is involved.