Evaluation of Hydrogen Embrittlement of Electroless Ni-P Plated 6061-T6 Aluminum Alloy by Three-Point Bending and Rotating Bending Fatigue Tests

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.