Author: Robby
Removing hydrogen from fasteners is crucial to prevent hydrogen embrittlement, which can lead to premature failure. Here are common methods used to remove hydrogen from fasteners:
Process: Fasteners are heated to a specific temperature (typically 190–230°C / 375–450°F) for a set duration (usually 4–24 hours).
Mechanism: Heat accelerates hydrogen diffusion, allowing trapped hydrogen to escape.
Best for: High-strength steel fasteners (ASTM A490, Grade 8, etc.) that have been electroplated or exposed to hydrogen sources.
Process: Letting fasteners sit at ambient temperature for 48–72 hours before use.
Mechanism: Slower hydrogen diffusion occurs naturally over time.
Best for: Low-risk applications where immediate use isn’t critical.
Process: Using ultrasonic or mechanical vibration to help dislodge hydrogen.
Effectiveness: Less proven than baking but sometimes used in combination with other methods.
Process: Using non-electroplated coatings (e.g., mechanical zinc, Dacromet, Geomet) that don’t introduce hydrogen during application.
Advantage: Eliminates the need for post-treatment.
Process: Adding hydrogen scavengers or inhibitors to plating baths to reduce hydrogen absorption.
Example: Using thiourea derivatives or modified electroplating processes.
For electroplated fasteners: Baking within 1–4 hours after plating is critical to prevent hydrogen trapping.
High-strength bolts (≥ 10.9 grade): Mandatory baking per standards like ASTM F1941, ISO 9587.
Testing: Notched tensile tests or sustained load tests can verify hydrogen embrittlement resistance.