Heat Treat Industry News
April 22, 2010
Bake-out Cycle After Plating
Question:
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?
Answer:
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).
by Daniel H. Herring - April 21, 2010
Daniel H. Herring
dherring@heat-treat-doctor.com
Dan Herring is president of THE HERRING GROUP Inc., which specializes in consulting services (heat treatment and metallurgy) and technical services (industrial education/training and process/equipment assistance. He is also a research associate professor at the Illinois Institute of Technology/Thermal Processing Technology Center.
References
1. Herring, D. H., “A Heat Treaters Guide to Hydrogen Embrittlement,” Industrial Heating, October 2004.
2. Mr. Alan Stone, Aston Metallurgical Services Co., Inc. (www.astonmet.com), private correspondence.
Source:
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