Material Cluster — Austenitic-Ferritic

Duplex Steel

The standard chloride-service upgrade from stainless — see the grade table below for full datasheets and equivalents within this family.

See All Grades ↓
DRAWINGNPRO-MAT-DX-001
FAMILYAUSTENITIC-FERRITIC
GRADES1 GRADE
STATUSREFERENCE / EDUCATIONAL
Family Overview

The standard chloride-service upgrade from stainless

Duplex stainless steel gets its name from a roughly 50/50 austenite-ferrite microstructure, which gives it meaningfully higher yield strength and better resistance to chloride pitting and stress-corrosion cracking than standard austenitic stainless grades like 316L. It's the default reach once a chloride-bearing service pushes past stainless steel's practical limits.

Duplex 2205 is the workhorse grade of this family, covering the large majority of seawater, brackish water, and moderate chloride process applications. For the most aggressive chloride environments, see the related Super Duplex Steel family.

Fig. — Grades in This Family

Grade in this family

GradeDesignationBest For
2205UNS S32205Chloride-bearing water, moderate acids, offshore and desalination service
Trade-offs

Advantages & limitations of the family

Advantages

  • Roughly double the yield strength of standard 316L
  • Strong resistance to chloride stress-corrosion cracking
  • Good cost-to-performance step up from austenitic stainless

Limitations

  • Work-hardens faster, requiring different machining parameters
  • Practical service temperature limit around 300°C
  • Requires controlled welding heat input to maintain phase balance
FAQ — Schema Marked

Questions about the Duplex Steel family

When chloride concentration and temperature combine to create meaningful pitting or stress-corrosion cracking risk — see the full guidance on the 2205 datasheet.

Yes, mildly — the ferrite phase, roughly half the microstructure, is magnetic, unlike fully austenitic stainless grades. This is normal and not a defect.

When 2205's PREN of approximately 35 isn't sufficient for the chloride concentration and temperature — see the Super Duplex Steel family for the higher-PREN alternative.

Why Specify With NPRO India

Engineering-reviewed tube sheets — not commodity plate

Every enquiry is checked against governing code, material compatibility and manufacturing feasibility before a quote is issued. Use our product, material, grade and standards guides to freeze the RFQ — then confirm with engineering.

Tube Sheets Products Materials Grades Standards Countries We Serve Blog Calculators Get a Quote →

sales@nproindia.in  ·  +91 9594639793

Not Sure Which Grade Fits Your Service?

Send your fluid composition and temperature — our engineering team will confirm the right grade.

Ask an Engineer →