Our customer is requiring us to bake nickel-plated parts for 90 minutes at 350ºF (175ºC). If the parts are exposed to a higher temperature, say 1700ºF (925ºC) instead, will that suffice?
Figure 2. Intergranular fracture of a plated screw due to hydrogen embrittlement[2] (Photograph courtesy of Aston Metallurgical Services Co. Inc.)
Exposing parts to 1700ºF (925ºC) does NOT have the same effect as baking the parts at 350ºF (175ºC). You are dealing with a complex phenomenon (hydrogen diffusivity) that is a function of both time and temperature.
Hydrogen bake-out cycles are performed after a plating process (Table 1) and before any additional processes are performed. The simple way to look at your plating process is to determine if, in any of the operations, the component is subjected to an environment in which hydrogen can diffuse into the part.
For a good book on plating, you might reference Metal Finishing's Guidebook and Directory (www.finishing.com/books/mfg.html).
A surprising number of delayed failures and problems with heat-treated fasteners are due to hydrogen attack in the form of embrittlement, especially if they undergo secondary operations such as plating (Fig. 2).
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