EN 1.4547 and EN 1.4462 are both corrosion-resistant stainless steel grades built for demanding environments, though they get there through different metallurgy. EN 1.4547 is 254 SMO, a high-alloy austenitic grade, while EN 1.4462 is a duplex grade commonly known as 2205. Their different structures produce real differences in corrosion resistance, strength, and application fit.
What Are EN 1.4547 and EN 1.4462 Plates?
EN 1.4547 Plates
EN 1.4547 Plates are known commercially as 254 SMO, a super-austenitic grade with high chromium, nickel and nitrogen content. Its defining feature is a molybdenum level around 6%, well above standard grades, driving its chloride resistance.
EN 1.4462 Plates
EN 1.4462 Plates carry a balanced austenitic-ferritic structure, roughly 22% chromium and 3% molybdenum. That dual-phase structure gives it a different strength and corrosion profile from EN 1.4547.
EN 1.4547 vs EN 1.4462: Key Differences
The table below sets out how the two grades compare on the factors that matter most.
| Factor | EN 1.4547 Plates | EN 1.4462 Plates |
| Material Type | Austenitic stainless steel | Duplex stainless steel |
| Common Grade | 254 SMO | 2205 |
| Chromium | Around 19.5–20.5% | Around 21–23% |
| Molybdenum | Around 6–7% | Around 2.5–3.5% |
| Nitrogen | Relatively high | Added for strength and resistance |
| Pitting Resistance | Very high | High |
| Stress Corrosion Cracking Resistance | Very good | Particularly strong due to duplex structure |
| Mechanical Strength | High | Generally higher yield strength |
| Typical Selection | Severe chloride and localized corrosion | Strength combined with corrosion resistance |
Exact composition and properties should be checked against the applicable product specification.
How Does Their Corrosion Resistance Compare?
Pitting and Crevice Corrosion
The higher molybdenum in EN 1.4547 gives it a strong edge in chloride-rich environments, where crevice corrosion and pitting attack weaker alloys fastest. EN 1.4462 still provides good pitting resistance through its own chromium, molybdenum, and nitrogen, though not usually to the same degree.
Stress Corrosion Cracking
EN 1.4462’s duplex structure is specifically valued for stress corrosion cracking resistance, a property its ferritic phase contributes. EN 1.4547 still offers strong resistance, but duplex construction gives EN 1.4462 the edge here.
Which Grade Offers Higher Mechanical Strength?
EN 1.4462’s duplex structure, combining austenitic and ferritic phases, generally delivers higher yield strength than EN 1.4547’s austenitic structure. That strength can support reduced thickness, making EN 1.4462 the common choice when strength and corrosion resistance both matter.
Where Are EN 1.4547 Plates Commonly Used?
Seawater Equipment
Direct seawater contact demands strong resistance to chloride-driven pitting.
Chemical Processing Equipment
Aggressive process chemicals that pit standard stainless call for EN 1.4547’s higher alloy content.
Desalination Systems
High-salinity streams test pitting resistance harder than most applications.
Pulp and Paper Equipment
Chloride-bearing liquors favour EN 1.4547’s resistance to localized attack.
Heat Exchangers
Exchanger surfaces in chloride-rich media benefit from strong crevice corrosion resistance at joints.
Where Are EN 1.4462 Plates Commonly Used?
Oil and Gas Equipment
Combined pressure and corrosion in oil and gas systems suit EN 1.4462’s strength and resistance together.
Chemical Processing
Equipment needing solid corrosion resistance without EN 1.4547’s added cost often specifies EN 1.4462.
Pressure Vessels
Higher yield strength lets EN 1.4462 support vessel design where wall thickness matters.
Structural Components
Load-bearing structural applications draw on its mechanical strength and corrosion resistance together.
Marine Equipment
Marine components needing stress corrosion cracking resistance alongside strength commonly specify EN 1.4462.
How Should You Choose Between EN 1.4547 and EN 1.4462?
Chloride concentration
Higher chloride levels push the choice toward EN 1.4547.
Pitting and crevice corrosion risk
Localized-attack-prone environments favour EN 1.4547 over standard duplex grades.
Mechanical loading
Significant structural load benefits from EN 1.4462’s higher yield strength.
Required yield strength
Where reduced wall thickness matters, EN 1.4462’s strength often decides it.
Operating temperature
Elevated temperatures affect both grades differently; check the specification.
Marine or chemical exposure
Specific chemistry, not general severity alone, should guide the choice.
Plate thickness
Available thickness ranges differ by grade and supplier; confirm before ordering.
Welding and fabrication requirements
Duplex EN 1.4462 needs different welding procedures to preserve its phase balance.
Applicable material standards
Project specifications often name one grade directly, overriding general preference.
Is EN 1.4547 Always Better Than EN 1.4462 for Corrosion Resistance?
Higher alloy content doesn’t automatically make one grade the best choice for every job. EN 1.4547 is often preferred where pitting resistance is the deciding factor. EN 1.4462 offers a strong combination of corrosion resistance and mechanical strength, often at lower cost.
Conclusion
EN 1.4547 and EN 1.4462 serve different selection requirements rather than competing on one measure. EN 1.4547 suits severe localized corrosion and heavy chloride exposure; EN 1.4462 offers a strong mix of corrosion resistance, stress corrosion cracking resistance, and mechanical strength. The final choice should rest on the service environment, loading, and applicable specifications.