| Hot-dip galvanized steel bollard | Carbon steel with a metallurgically bonded zinc coating | Hot-dip galvanizing applied after steel fabrication; sealed drainage holes and protected cut edges are recommended | Good in outdoor urban and industrial environments; performance decreases in continuous salt spray or stagnant water | Good outdoor durability; the zinc surface naturally develops a protective patina | Roadside protection, parking areas, loading zones, warehouses, and public spaces | ISO 1461; ASTM A123/A123M; coating design may also be evaluated under ISO 12944 | Low; inspect for mechanical damage, white rust, and exposed steel at cut or drilled areas | Low to medium |
| Duplex-coated steel bollard | Carbon steel with zinc protection and an organic topcoat | Hot-dip galvanizing plus powder coating or a liquid paint system; the two layers provide barrier and sacrificial protection | Very good for humid, industrial, and moderately saline environments when surface preparation is properly controlled | Very good when the topcoat is selected for exterior UV exposure; color and gloss depend on the coating chemistry | Coastal streets, car parks, commercial sites, transport facilities, and high-visibility public projects | ISO 12944; ISO 1461; ASTM A123/A123M; coating performance can be verified with dry-film-thickness testing | Low to medium; repair scratches and impact damage before corrosion reaches the steel substrate | Medium |
| 304 stainless steel bollard | Austenitic stainless steel containing chromium and nickel | Corrosion resistance is provided by the passive chromium-oxide surface; brushed, satin, or polished finishes are common | Good for general outdoor use; may develop tea staining or pitting in coastal areas with high chloride exposure | Excellent color stability because the metal is not dependent on an organic paint film | Architectural entrances, shopping areas, office buildings, pedestrian zones, and indoor-outdoor transitions | ASTM A240/A240M; EN 10088; fabrication should follow suitable stainless-steel cleaning and passivation practices | Medium; periodic cleaning removes chloride deposits and surface contamination | Medium to high |
| 316 stainless steel bollard | Austenitic stainless steel containing molybdenum for improved chloride resistance | Integral passive surface; a suitable finish and post-fabrication cleaning help preserve corrosion resistance | Very good for coastal, marine, de-icing-salt, and wastewater-adjacent environments; local conditions still affect performance | Excellent exterior weather and UV performance without relying on paint | Seafront promenades, marinas, coastal roads, salt-storage areas, hospitals, and premium public sites | ASTM A240/A240M; EN 10088; stainless fabrication should include appropriate pickling, passivation, or equivalent cleaning where required | Low to medium; rinse salt deposits and avoid carbon-steel contamination during fabrication or installation | High |
| Duplex 2205 stainless steel bollard | Duplex stainless steel with a mixed ferritic-austenitic microstructure | Intrinsic corrosion resistance with higher strength than common austenitic grades; welding procedure control is important | Excellent resistance to chloride-induced pitting and stress-corrosion cracking in demanding environments | Excellent UV and weather performance; surface finish still affects appearance and cleaning behavior | Severe marine exposure, industrial sites, chemical facilities, and projects requiring high strength and corrosion resistance | ASTM A240/A240M; EN 10088; welding and heat-input controls should be specified for fabricated components | Low; routine washing and inspection are normally sufficient when the material is correctly fabricated | Very high |
| Aluminum alloy bollard | Aluminum alloy, commonly formed by extrusion or casting | Natural oxide layer; anodizing or exterior powder coating can improve appearance and surface protection | Good atmospheric corrosion resistance; galvanic corrosion must be controlled where aluminum contacts dissimilar metals | Good when anodized or coated with an exterior-grade system; unprotected surfaces may show oxidation or staining | Light-duty pedestrian areas, campuses, parking facilities, and projects where low weight is important | ASTM B209/B221, depending on product form; anodizing may be specified under architectural anodizing standards | Low; inspect coating, fasteners, and contact points for galvanic corrosion | Medium |
| UV-stabilized HDPE bollard | High-density polyethylene with UV stabilizers and integral color or molded finish | Does not rust; protection depends on polymer formulation, UV stabilization, wall thickness, and installation design | Excellent resistance to water, many salts, and a wide range of common chemicals; not suitable for every solvent or heat condition | Good when UV-stabilized; color fading and embrittlement remain possible after prolonged severe exposure | Temporary traffic control, pedestrian guidance, utility areas, parking lots, and impact-warning installations | Material performance should be supported by the applicable polyethylene specification and UV-weathering test data | Low; inspect for cracking, fading, deformation, and damage from vehicle impact or heat | Low to medium |
| Zinc-rich primed and top-coated steel bollard | Carbon steel protected with a zinc-rich primer and compatible finishing coats | Multi-coat paint system using zinc-rich primer, intermediate coat, and exterior topcoat; system selection depends on the corrosivity category | Good to very good when surface preparation, coating thickness, edge treatment, and curing are properly controlled | Good with a UV-resistant topcoat; the finish may require renewal sooner than stainless steel in severe exposure | Custom-color projects, industrial areas, architectural sites, and installations requiring a specified coating system | ISO 12944; ISO 8501 for surface preparation references; coating thickness should be verified during quality control | Medium; inspect coating breakdown, rust creep, impact points, welds, and concealed water traps | Medium |