What Is Hydrogen Embrittlement?
Hydrogen embrittlement is a condition in which metal—especially high-strength steel—experiences a loss of mechanical performance and becomes more
brittle after absorbing hydrogen during manufacturing. This can result in cracks or even sudden fracture. It typically occurs in processes such as electroplating,
pickling, or cleaning, and poses a serious, often hidden, risk to the reliability of industrial components.
Root Causes of Hydrogen Embrittlement
Hydrogen Absorption During Processing
During operations like electroplating, acid pickling, or degreasing, hydrogen atoms can penetrate the metal’s microstructure.High Sensitivity of Stronger Materials
The higher the strength of the steel, the more susceptible it is to hydrogen embrittlement. Fasteners of Grade 8, 10.9, or 12.9 are particularly vulnerable.Hydrogen Diffusion and Accumulation
Once inside the material, hydrogen can migrate and accumulate along grain boundaries or microscopic flaws. This build-up can initiate microcracks that grow over time.
Solution: Post-Plating Hydrogen Relief Baking
To reduce the risk of hydrogen embrittlement, a hydrogen relief heat treatment—commonly referred to as baking—should be added to the production process.
This step drives out absorbed hydrogen from the metal, improving product durability and mechanical consistency.
Recommended baking durations after electroplating:
Grade 5 and 8.8 fasteners: Generally low risk; baking is optional but can further enhance product safety.
Grade 8: Bake for 8 hours.
Grade 10.9: Bake for at least 4 hours.
Grade 12.9 ( high strength): Bake for 8 hours.
Baking should take place shortly after plating to prevent hydrogen from diffusing deeper into the material. For best results, this process is typically performed
by the plating supplier to ensure product integrity.
Why Is Hydrogen Relief Process So Important?
Including a hydrogen relief step is essential for minimizing the risk of failure due to embrittlement. It not only protects against cracks and premature breakage but
also enhances product consistency and long-term reliability—making it a critical quality assurance measure for any high-strength metal component.