Hydrogen Embrittlement & Electroplating: What You Need to Know
The electroplating process involves the use of an aqueous electrolyte solution (known as the plating “bath”) that consists of dissolved metal salts, ions and various chemicals. However, the primary bath component is something we all use every day: water. As most of us learned in elementary school, every water molecule is comprised of two hydrogen atoms and one oxygen atom, resulting in the familiar formula of H2O.
As the electroplating process typically involves the immersion of the substrate into the plating bath, hydrogen from the water may be co-deposited onto the surface of the substrate along with the metal ions. This can result in a potentially harmful condition known as hydrogen embrittlement.
What Is Hydrogen Embrittlement?
Hydrogen embrittlement is a loss of ductility due to excess hydrogen absorption, which makes the material brittle. It occurs because hydrogen atoms are much smaller than those that comprise the deposited metal. This causes the hydrogen atoms to migrate into the crystal lattice of the base metal and become lodged between the individual metal atoms. This can substantially increase the stress of applied forces within the base metal and result in fracturing. Hydrogen embrittlement can also occur during pre-plating processes such as cleaning and pickling, as well as during electroless plating procedures.
How to Prevent Hydrogen Embrittlement
While hydrogen embrittlement can cause significant damage to a part, there are a number of techniques that can prevent it from occurring:
- Post-plating baking: Baking the part immediately after plating can reverse the effects of hydrogen embrittlement in most cases. General guidelines call for baking the part for four hours at a temperature of 375º F within one hour of plating. Most steels typically require a lower temperature in the range of 200-300º F.
- Adding inhibitors during pickling: Corrosion of the base metal may occur during pickling, leading to vigorous hydrogen evolution that in turn may cause embrittlement. The use of inhibitors during the pickling step can reduce or eliminate this corrosion, resulting in a decrease in hydrogen pick-up.
- Substituting metal alloys: Certain metals, particularly extremely high-strength steels, are more susceptible to hydrogen embrittlement than others. Alloying these high-risk metals with ones exhibiting lower hydrogen diffusion rates such as nickel, zinc or molybdenum can be extremely effective in preventing hydrogen embrittlement.
Sharretts Plating Company Knows How to Stop Hydrogen Embrittlement in Its Tracks
Your choice of metal finishing company will have a major impact in preventing the potentially devastating effects of hydrogen embrittlement in your products. With more than 90 years of metal finishing experience, you can count on the professionals at SPC to deliver a high-quality product that is free of cracks or fractures. Contact us to learn more about our embrittlement-free metal finishing and electroplating processes, or learn about our Plating Consulting Services.