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In this study, 6061-T6 aluminum alloys were plated with electroless Ni–P with different phosphorus content and three-point bending and rotating 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 un-treated 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 rotating bending machine. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this study, with the aim of improving the fatigue characteristics of the A7075 aluminum alloy, A7075-T6511 alloy rod specimens were plated with electroless NiP with different compositions, and the fatigue characteristics were evaluated by a rotary bending fatigue test. The fatigue strength of the specimen plated with low-P type was higher than that of the un-plated specimen. However, the fatigue strength of the specimen plated with high-P type was significantly lower than that of the un-plated specimen, and the fatigue strength of the specimen plated with medium-P type was also lower though the extent was not so significant. It was speculated that these reductions in fatigue strength were due to hydrogen embrittlement by the hydrogen introduced into the specimen during the plating. [ABSTRACT FROM AUTHOR]

In this study, A2017-T4 aluminum alloy was plated with electroless NiP with different phosphorus content and rotary bending fatigue test was conducted to investigate the effect of hydrogen by plating on fatigue properties. The fatigue strength of the low-phosphorus type NiP 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. The decrease in fatigue strength of the high phosphorus type plating specimen was attributed to hydrogen induced by plating from hydrogen analysis. Thus, despite the previous report that 2000 series aluminum alloys do not exhibit hydrogen embrittlement in slow strain rate tensile tests under wet condition, it was found that A2017-T4 aluminum alloy undergo hydrogen embrittlement when the alloy is plated with high-phosphorus type electroless NiP and fatiguetested on rotary bending machine. [ABSTRACT FROM AUTHOR]

In this study, the effect of anodization and electroless NiP plating on the fatigue strength of commercial A5052-H14 and A2017-T4 aluminum alloys was investigated. The coated aluminum alloys were tested using a rotary bending fatigue testing machine. Anodization led to a slight increase in the fatigue strength of the A2017-T4 alloy of approximately 10% because of the suppression of the generation of fatigue crack, and anodization with a 5-µm thickness for A5052-H14 also led to a slight increase in the fatigue strength. However, anodization with a 20-µm thickness for A5052-H14 led to reduced fatigue strength because of the pits that formed in the film. In addition, electroless NiP plating drastically improved the fatigue strength of the A5052-H14 alloy by suppressing the generation of fatigue crack. It also improved the fatigue strength of the A2017-T4 alloy in the high-stress region. However, the fatigue strength in the low-stress region was the same as that of the non-coated specimens. This fatigue strength should have originated from the hydrogen embrittlement by the hydrogen introduced into the specimen during the plating. [ABSTRACT FROM AUTHOR]

Hydrogen embrittlement of SK85 high-strength steel sheets was evaluated through a three-point bending test. The effects of electroless NiP plating and Ni electroplating on hydrogen embrittlement were examined with respect to the hydrogen permeability of the plated films. On the morrow of the plating, electroless NiP plating indicates a high degree of hydrogen embrittlement, irrespective of the phosphorus content in the film. However, hydrogen embrittlement of Ni electroplating is further suppressed than that of electroless NiP plating, which can be attributed to the excellent hydrogen diffusing ability of Ni electroplating. These results demonstrate that the hydrogen permeability of a plated film is an important factor for hydrogen embrittlement. Hydrogen present on the plated film surface was visualized by employing the hydrogen microprint technique, and the corresponding results reveal that the hydrogen permeability of the plated film is dependent on the film crystal structure. Furthermore, the pits in the film can become a route for hydrogen emission. [ABSTRACT FROM AUTHOR]