In this study, 6061–T6 aluminum alloys were plated with electroless Ni–P with different phosphorus content and three–point bending and rotary bending fatigue
tests. The effects of hydrogen due to plating on mechanical properties were investigated. It was shown that the ductility decreased immediately after low–phosphorus
type and high–phosphorus type Ni–P plating by three–point bending test because a hydrogen was introduced into the alloys. The fatigue strength of the low–phosphorus
type Ni–P plated specimen was higher than that of the untreated specimen, while that of the high–phosphorus type plated specimen was much lower. It is clear that the
fatigue strength differs greatly depending on the phosphorus content in the plating film. 6061–T6 aluminum alloy have been reported to exhibit no hydrogen embrittlement
in low strain rate tensile tests under wet condition. However, it was found that hydrogen embrittlement occurred when 6061–T6 aluminum alloy was plated with the high–
phosphorus type electroless Ni–P and fatigue–tested on rotary bending machine.