Corrosion Mechanism and Long-Term Anti-Corrosion System of Rail Components
What are the main types of corrosive environments for rail components?
Atmospheric corrosion: humid heat, acid rain, industrial pollution; Salt spray corrosion: coastal areas, salt lake areas; De-icing agent corrosion: de-icing salt in northern winters; Soil/groundwater corrosion: low-lying areas, underground structures; Stray current corrosion: subway and light rail sections.
How serious is the damage to components?
Surface rust forms gaps → stress concentration → fatigue fracture; Thread rust → jamming, inability to disassemble, inaccurate torque, loosening; Cross-sectional corrosion thinning → strength reduction → sudden failure; Damage to the anti-corrosion layer → localized accelerated corrosion.
Comparison of mainstream long-term anti-corrosion processes:
Hot-dip galvanizing: low cost, long service life, suitable for conventional speed trains and open-air applications; Dacromet/zinc-aluminum coating: strong salt spray resistance, no hydrogen embrittlement, suitable for high-speed rail, subways, and high-strength bolts; Stainless steel/weathering steel: longest service life, suitable for extreme corrosive environments; Composite coating: galvanizing + sealing paint, combining corrosion resistance and wear resistance.
Key principles of corrosion protection design:
Avoid water and dust accumulation and gaps in the structure; avoid excessive coating on load-bearing surfaces to prevent slippage and torque inaccuracies; prevent hydrogen embrittlement in high-strength components; ensure corrosion protection does not impair mechanical or fatigue properties.
Key points for corrosion protection maintenance during operation and maintenance:
Repair damaged coatings promptly; treat rust early to prevent its spread; upgrade corrosion protection levels in batches for severely corroded sections; establish environmental records for differentiated selection.