Preventing Hydrogen Embrittlement in Steel Fuel Tank Welds
To avoid hydrogen embrittlement when welding steel fuel tanks, a systematic approach is critical, as this phenomenon—caused by hydrogen diffusion into the weld zone—can lead to catastrophic fractures under stress.
Ensure the steel substrate is free of contaminants like oil, grease, or rust, which can release hydrogen during welding. Use a wire brush or grit blasting to clean surfaces, and store electrodes in sealed, moisture-proof containers. For high-strength steels, pre-weld baking of electrodes at 300–400°C removes adsorbed moisture, a primary hydrogen source.
Welding Parameter Control
- Opt for low-hydrogen processes (SAW or GMAW with low-hydrogen fillers)
- Avoid high heat inputs which prolong cooling times
- Maintain a stable arc and avoid excessive voltage
- Prevents ionization of atmospheric moisture
Bake the welded tank at 200–300°C for 2–4 hours to drive out diffused hydrogen—a process called "baking out." This is especially vital for thick sections or high-strength steels, where hydrogen trapping is more likely.
Design Considerations
- Avoid sharp corners or abrupt thickness changes
- These create stress concentrations where embrittlement initiates
- Post-weld grinding to smooth weld profiles
- Reduces stress concentration points
Testing Methods
- Ultrasonic inspection to detect cracks
- Hydrogen content analysis on weld samples
- Stress corrosion cracking tests
- Microstructural analysis for hydrogen damage
By combining these measures, hydrogen embrittlement in steel fuel tank welds can be effectively prevented, ensuring structural integrity and safety.