Metallurgy|7 min read
Mitigating Hydrogen Embrittlement in Plating High-Strength Fasteners via High-Frequency Pulsed Waveforms
Investigating the role of pulse off-times (Toff) in releasing trapped hydrogen and eliminating costly post-plating baking steps.
Hydrogen embrittlement is a primary cause of catastrophic, unannounced mechanical failures in Class 10.9 and 12.9 high-tensile bolts, automotive springs, and hardened steel fasteners following zinc or nickel electroplating.
How Hydrogen Embrittlement Occurs:
During electrodeposition, hydrogen ion reduction occurs simultaneously with metal reduction. Small atomic hydrogen atoms diffuse into the steel lattice, clustering at grain boundaries and causing severe internal stress embrittlement.
Loni Pulsed Power Countermeasure:
Loni pulse rectifiers apply microsecond off-times (Toff), allowing atomic hydrogen gas bubbles to detach from the cathode surface and float away before diffusing into the substrate.
Engineering Achievements:
- Preserves 100% of fatigue limits and tensile strength in critical automotive and structural fasteners.
- Reduces or completely eliminates energy-intensive 24-hour post-baking heat treatments at 200°C.
- Guarantees strict compliance with international standards ISO 4042 and ISO 9588.
Power Frequency Stability Pattern
Stabilized output current within industrial standards (> 99.5%)