What is Hydrogen Embrittlement Failure? Causes, Significance, Mitigations Explained

Causes

<include general explanation>

At a high level, susceptibility of bolts to Hydrogen Embrittlement increases based on the following factors:

• Steel must be high strength, typically over 1000 N/mm2.
  This includes grade 10.9 bolts and above. 
• Hardness greater than 380 Hv (Vickers hardness)
• Low ductility (% elongation less than ...)
• Corrosion protection coating process (e.g. hot-dip galvinising, acid treatment, etc.)

※ What are High Strength Friction Grip Bolts? Applications. When to Use

※ What is Hardness? Meaning, Significance, How to Measured. Explained

Significance

Hydrogen embrittlement causes a significant reduction in the ductility of the bolts, and reduces the capacity of the bolt significantly.

Mitigation Measures

Consider using different coating method

Consider using Tension Control Bolts (TCBs) which have a lower hardness, improved ductility, and are generally corrosion treated using Thermal Diffusion coatings such as Greenkote(TM).

※ What are Tension Control Bolts? Applications. Differences with HSFG bolts

Consider using larger diameter bolts of grade 8.8 or lower