Causes and Treatment of Hydrogen Embrittlement in Electroplating

Causes and Treatment of Hydrogen Embrittlement in Electroplating

Author: Robby

The main reasons for electroplating to produce hydrogen embrittlement include the following aspects:

1. The plating process itself: hydrogen embrittlement is easily generated during the plating process, such as pickling, plating and other steps. For example, springs are prone to fracture during plating.
2. Raw materials: High-strength steels are sensitive to hydrogen embrittlement, especially when their strength exceeds 1,250 MPa, and the absorption of a small amount of hydrogen can lead to significant hydrogen embrittlement fracture. In contrast, ordinary steels do not suffer from hydrogen embrittlement even when they absorb larger amounts of hydrogen2.
3. Machining: Hydrogen penetration into the metal can occur due to lubricant decomposition during pre-plating processes such as roll forming, machining, drilling, and grinding. Machining, grinding and other processes after hardening heat treatment also increase the risk of hydrogen embrittlement.
4. Heat treatment: The heat treatment process has a greater impact on hydrogen embrittlement after plating of high strength steels and elastic fasteners. Hardnesses up to 45 HRC can easily induce or cause fracture of elastic fasteners.
5. Plating solution composition: In the production process of electroplating nickel brightener, too high a content of secondary brightener, too high a current density, and a high content of zinc, lead and other metal impurities in the plating solution will lead to a brittle coating and increase the risk of hydrogen embrittlement.
6. Metal material properties: hydrogen atoms in the metal internal diffusion and recombination of hydrogen molecules, the formation of high-pressure “hydrogen bubble”, which will cause local stress concentration, weakening the cohesion of the metal material, resulting in increased material embrittlement Hydrogen embrittlement

Measures to prevent and resolve hydrogen embrittlement include

1. Control the plating process: Optimize the plating process to reduce the generation and penetration of hydrogen ions.
2. Selection of suitable raw materials: Use materials that are not sensitive to hydrogen embrittlement or reduce the strength of the material.
3. Machining and heat treatment: Select appropriate process parameters during machining and heat treatment to reduce hydrogen penetration.
4. De-hydrogenation: Perform de-hydrogenation after plating, e.g. heat treatment to reduce the hydrogen content within the metal.
5. Control the composition of the plating solution: Reasonable control of the brightener content and impurity content in the plating solution, to avoid excessive use leading to increased brittleness of the plated layer.

Through the above measures, the occurrence of hydrogen embrittlement in the plating process can be effectively prevented and reduced.