Superior Corrosion
Resistance
Resistance to chloride pitting, crevice corrosion and stress corrosion cracking.
ABOUT THIS MATERIAL
Why
Super Duplex Steel Castings?
Super duplex steel castings combine high mechanical strength with resistance to aggressive chloride environments. They are used for pump casings, impellers, valve bodies and critical fluid-handling components in marine, offshore, chemical and desalination systems.
At Bhanu Special Castings, we review your drawing, service conditions and inspection requirements to select a suitable casting grade and manufacturing approach.
UNDERSTANDING THE MATERIAL
Ferritic–Austenitic Structure
Super duplex stainless steel contains both ferrite and austenite. Controlled phase balance supports high strength, corrosion resistance and useful toughness.
Chromium, molybdenum and nitrogen enhance resistance to chloride pitting and crevice corrosion. Performance depends on casting grade, solution heat treatment and the intended service conditions.
Key Advantages
Superior Corrosion
High Mechanical
Strength
Higher yield strength than many conventional austenitic stainless steels.
Industrial
Durability
Reliable performance in appropriately engineered corrosive environments.
Long
Service Life
Potential to reduce maintenance and component replacement costs.
MATERIAL PERFORMANCE
The Strength & Corrosion Resistance Advantage
Engineered for Demanding Chloride Environments
Super duplex steel castings combine a ferritic–austenitic structure with chromium, molybdenum and nitrogen alloying to support high mechanical strength and resistance to localized corrosion in suitably selected service conditions.
HIGH MECHANICAL STRENGTH
Dual-phase alloy structure
For load-bearing pressure and fluid-handling components
+
CHLORIDE CORROSION RESISTANCE
Alloying for aggressive environments
Resistance to pitting, crevice corrosion and stress corrosion cracking
Performance depends on grade selection, heat treatment, fabrication quality and actual operating conditions.
Why This Combination Matters
High strength and corrosion resistance support pump casings, impellers and valve bodies used in marine, offshore, desalination and chemical processing equipment.
Application & Quality Considerations
Review service temperature, chloride concentration, process chemistry and design stresses. Verify heat treatment, phase balance and inspection requirements against the purchase specification.
INTERNATIONAL STANDARDS & GRADE SPECIFICATIONS
Super Duplex Steel Casting Grades Across International Standards
Super duplex castings are ordered to casting specifications that define chemistry, heat treatment, mechanical properties and inspection. ASTM A890 covers general applications; ASTM A995 covers pressure-containing components.
Representative ASTM casting grades include super duplex 5A / CE3MN and 6A / CD3MWCuN, and the higher-alloy hyper duplex 7A / CD3MWN. European corrosion-resistant casting specifications include selected 25% chromium ferritic–austenitic grades under EN 10283 and its national adoptions.
Select the casting grade against service conditions and the purchase specification. Cast-grade designations and wrought grades such as S32750 and S32760 are distinct; they are not interchangeable ordering specifications.
Cross-Reference: Casting Standards & Grades
| Country / Region | Specification Route | Representative Casting Grades |
|---|---|---|
 India | ASTM A890 / A995* | 5A / CE3MN 6A / CD3MWCuN 7A / CD3MWN |
 USA | ASTM A890 / A995 | 5A / CE3MN 6A / CD3MWCuN 7A / CD3MWN |
 Germany | DIN EN 10283 | 1.4468 / GX2CrNiMoN25-6-3 1.4417 / GX2CrNiMoN25-7-3 1.4469 / GX2CrNiMoN26-7-4 |
 International / Europe | EN 10283 | 1.4468 / GX2CrNiMoN25-6-3 1.4417 / GX2CrNiMoN25-7-3 1.4469 / GX2CrNiMoN26-7-4 |
 China | ASTM A890 / A995* | 5A / CE3MN 6A / CD3MWCuN 7A / CD3MWN |
 Japan | ASTM A890 / A995* | 5A / CE3MN 6A / CD3MWCuN 7A / CD3MWN |
 United Kingdom | BS EN 10283 | 1.4468 / GX2CrNiMoN25-6-3 1.4417 / GX2CrNiMoN25-7-3 1.4469 / GX2CrNiMoN26-7-4 |
 France | NF EN 10283 | 1.4468 / GX2CrNiMoN25-6-3 1.4417 / GX2CrNiMoN25-7-3 1.4469 / GX2CrNiMoN26-7-4 |
 Italy | UNI EN 10283 | 1.4468 / GX2CrNiMoN25-6-3 1.4417 / GX2CrNiMoN25-7-3 1.4469 / GX2CrNiMoN26-7-4 |
 Australia | ASTM A890 / A995* | 5A / CE3MN 6A / CD3MWCuN 7A / CD3MWN |
 South Africa | ASTM A890 / A995* | 5A / CE3MN 6A / CD3MWCuN 7A / CD3MWN |
 Russia | ASTM A890 / A995* | 5A / CE3MN 6A / CD3MWCuN 7A / CD3MWN |
 Spain | UNE EN 10283 | 1.4468 / GX2CrNiMoN25-6-3 1.4417 / GX2CrNiMoN25-7-3 1.4469 / GX2CrNiMoN26-7-4 |
 Sweden | SS EN 10283 | 1.4468 / GX2CrNiMoN25-6-3 1.4417 / GX2CrNiMoN25-7-3 1.4469 / GX2CrNiMoN26-7-4 |
 Norway | NS EN 10283 | 1.4468 / GX2CrNiMoN25-6-3 1.4417 / GX2CrNiMoN25-7-3 1.4469 / GX2CrNiMoN26-7-4 |
 South Korea | ASTM A890 / A995* | 5A / CE3MN 6A / CD3MWCuN 7A / CD3MWN |
COUNTRY-WISE MATERIAL GRADES
Interactive Country-Wise Chemical Composition Tables
Select a country to explore super duplex steel casting specification routes and selected chemical composition limits (mass %).
ASTM A890 / A995 — Super & Hyper Duplex Casting Grades
| Casting Grade | C % | Cr % | Ni % | Mo % | N % | Cu % | W % |
|---|---|---|---|---|---|---|---|
| 5A / CE3MN | ≤0.030 | 24.0–26.0 | 6.0–8.0 | 4.0–5.0 | 0.10–0.30 | — | — |
| 6A / CD3MWCuN | ≤0.030 | 24.0–26.0 | 6.5–8.5 | 3.0–4.0 | 0.20–0.30 | 0.50–1.00 | 0.50–1.00 |
| 7A / CD3MWN | ≤0.030 | 26.0–28.0 | 6.0–8.0 | 2.0–3.5 | 0.30–0.40 | ≤1.00 | 3.0–4.0 |
ASTM purchase-specification route for Indian projects; these are not BIS grade designations. Values are mass %. Selected elements only; Mn, Si, P, S and other standard requirements also apply; 7A additionally specifies B, Ba and Ce+La. — means no limit stated here, not zero. The specified standard edition and purchase order govern.
ASTM A890 / A995 — Super & Hyper Duplex Casting Grades
| Casting Grade | C % | Cr % | Ni % | Mo % | N % | Cu % | W % |
|---|---|---|---|---|---|---|---|
| 5A / CE3MN | ≤0.030 | 24.0–26.0 | 6.0–8.0 | 4.0–5.0 | 0.10–0.30 | — | — |
| 6A / CD3MWCuN | ≤0.030 | 24.0–26.0 | 6.5–8.5 | 3.0–4.0 | 0.20–0.30 | 0.50–1.00 | 0.50–1.00 |
| 7A / CD3MWN | ≤0.030 | 26.0–28.0 | 6.0–8.0 | 2.0–3.5 | 0.30–0.40 | ≤1.00 | 3.0–4.0 |
ASTM casting grades 5A, 6A and 7A. Values are mass %. Selected elements only; Mn, Si, P, S and other standard requirements also apply; 7A additionally specifies B, Ba and Ce+La. — means no limit stated here, not zero. The specified standard edition and purchase order govern.
EN 10283 — Selected 25% Cr Duplex / Super Duplex Casting Grades
| Casting Grade | C % | Cr % | Ni % | Mo % | N % | Cu % | W % |
|---|---|---|---|---|---|---|---|
| 1.4468 / GX2CrNiMoN25-6-3 | ≤0.030 | 24.5–26.5 | 5.5–7.0 | 2.5–3.5 | 0.12–0.25 | ≤0.50 | — |
| 1.4417 / GX2CrNiMoN25-7-3 | ≤0.030 | 24.0–26.0 | 6.0–8.5 | 3.0–4.0 | 0.15–0.25 | ≤1.00 | ≤1.00 |
| 1.4469 / GX2CrNiMoN26-7-4 | ≤0.030 | 25.0–27.0 | 6.0–8.0 | 3.0–5.0 | 0.12–0.22 | ≤1.30 | — |
Selected EN 10283 chemical limits; cast designations are distinct from wrought grades. Grade selection and any specified PREN requirement must be verified for the intended service. Values are mass %. Selected elements only; Mn, Si, P, S and other standard requirements also apply; 7A additionally specifies B, Ba and Ce+La. — means no limit stated here, not zero. The specified standard edition and purchase order govern.
ASTM A890 / A995 — Super & Hyper Duplex Casting Grades
| Casting Grade | C % | Cr % | Ni % | Mo % | N % | Cu % | W % |
|---|---|---|---|---|---|---|---|
| 5A / CE3MN | ≤0.030 | 24.0–26.0 | 6.0–8.0 | 4.0–5.0 | 0.10–0.30 | — | — |
| 6A / CD3MWCuN | ≤0.030 | 24.0–26.0 | 6.5–8.5 | 3.0–4.0 | 0.20–0.30 | 0.50–1.00 | 0.50–1.00 |
| 7A / CD3MWN | ≤0.030 | 26.0–28.0 | 6.0–8.0 | 2.0–3.5 | 0.30–0.40 | ≤1.00 | 3.0–4.0 |
ASTM purchase-specification route for Chinese projects; these are not GB/T grade designations. Values are mass %. Selected elements only; Mn, Si, P, S and other standard requirements also apply; 7A additionally specifies B, Ba and Ce+La. — means no limit stated here, not zero. The specified standard edition and purchase order govern.
ASTM A890 / A995 — Super & Hyper Duplex Casting Grades
| Casting Grade | C % | Cr % | Ni % | Mo % | N % | Cu % | W % |
|---|---|---|---|---|---|---|---|
| 5A / CE3MN | ≤0.030 | 24.0–26.0 | 6.0–8.0 | 4.0–5.0 | 0.10–0.30 | — | — |
| 6A / CD3MWCuN | ≤0.030 | 24.0–26.0 | 6.5–8.5 | 3.0–4.0 | 0.20–0.30 | 0.50–1.00 | 0.50–1.00 |
| 7A / CD3MWN | ≤0.030 | 26.0–28.0 | 6.0–8.0 | 2.0–3.5 | 0.30–0.40 | ≤1.00 | 3.0–4.0 |
ASTM purchase-specification route for Japanese projects; these are not JIS grade designations. Values are mass %. Selected elements only; Mn, Si, P, S and other standard requirements also apply; 7A additionally specifies B, Ba and Ce+La. — means no limit stated here, not zero. The specified standard edition and purchase order govern.
OUR PRODUCT PORTFOLIO
High-Performance Super Duplex Cast Components
Super Duplex Steel Castings are used to manufacture precision-engineered components for corrosive, high-pressure, and demanding industrial environments.
01
Pump Castings
Designed for efficient handling of seawater, chemicals, and aggressive industrial fluids.
Subproducts
02
Valve Castings
High-strength corrosion-resistant components for industrial flow control.
Subproducts
03
Pipe & Flow Control Castings
Cast components for high-performance piping and fluid distribution systems.
Subproducts
04
Marine & Offshore Castings
Components engineered for demanding marine and offshore environments.
Subproducts
05
Chemical Processing Castings
Corrosion-resistant parts for chemical handling and processing equipment.
Subproducts
06
Custom Engineered Castings
Application-specific components developed according to engineering drawings and customer specifications.
Subproducts
Step-by-Step Manufacturing Process
From Raw Material to
Finished Super Duplex Steel Components
Our super duplex casting workflow combines grade-specific alloy control, casting soundness, solution heat treatment and verification of specified properties and phase balance.
Raw Material Selection
Select traceable steel scrap, suitable foundry returns and alloy additions for the specified super duplex casting grade.
Pattern & Mould Preparation
Prepare patterns, cores and moulds to approved drawings, with suitable gating, feeding and shrinkage allowances.
Melting & Alloying
Melt the prepared charge and control chromium, nickel, molybdenum and other specified alloying elements for the selected grade.
Chemical Analysis & Melt Control
Verify melt chemistry, including nitrogen by an appropriate analytical method; correct deviations before releasing the heat for pouring.
Controlled Metal Pouring
Pour at the established temperature using suitable ladle handling, gating and feeding arrangements.
Cooling & Solidification
Control solidification and cooling to support casting soundness and limit shrinkage, segregation and distortion.
Shakeout & Fettling
Remove moulding sand, runners and risers; clean and dress the casting surfaces for subsequent operations.
Solution Heat Treatment & Quenching
Apply grade-specific solution heat treatment and rapid cooling to obtain the required ferritic–austenitic structure and control harmful intermetallic phases.
Machining & Surface Finishing
Complete specified machining through partner facilities and prepare functional surfaces to drawing requirements.
Final Inspection & Dispatch
Verify dimensions, chemistry, specified mechanical properties and phase balance. Complete required NDT, corrosion testing, documentation and packing.
SECTION 10 / MATERIAL PROPERTIES
Mechanical & Physical Properties
Super Duplex Steel Castings
Strength
Toughness
Ductility
Thermal Properties
Mechanical Properties
| Property | ASTM A890 Grade 5A | ASTM A890 Grade 6A |
|---|---|---|
| Tensile Strength | 690 MPa min. | 690 MPa min. |
| Yield Strength (0.2%) | 515 MPa min. | 485 MPa min. |
| Elongation | 18% min. | 20% min. |
| Hardness | Depends on specification | Depends on specification |
| Impact Toughness | As specified | As specified |
| Microstructure | Austenitic–Ferritic | Austenitic–Ferritic |
Representative grade values; confirm requirements against the contractual standard edition and heat-treated condition.
Typical Physical Properties
| Property | Approximate Value |
|---|---|
| Density | 7.75–7.85 g/cm³ |
| Elastic Modulus | 200 GPa |
| Thermal Conductivity | 14–16 W/m·K |
| Specific Heat Capacity | 500 J/kg·K |
| Thermal Expansion | 13 × 10⁻⁶/K |
| Magnetic Behaviour | Generally magnetic due to ferrite. |
Physical values are indicative and vary by grade and temperature.
Final acceptance criteria follow the agreed material specification and purchase requirements.
METALLURGICAL ENGINEERING
Microstructure & Metallurgical Characteristics
Controlled Austenite–Ferrite Microstructure for Reliable Performance
Super duplex steel castings combine austenite and ferrite. Proper solution heat treatment and controlled cooling help achieve the required mechanical properties and corrosion resistance.
ILLUSTRATIVE MICROSTRUCTURE
Concept visual — not a measured micrograph
Performance depends on phase balance, alloy chemistry and heat treatment.
Microstructural Characteristics
| Feature | Description | Importance |
|---|---|---|
| Austenite | FCC crystal structure | Toughness and ductility |
| Ferrite | BCC crystal structure | Strength and SCC resistance |
| Phase Balance | Controlled ferrite–austenite ratio | Overall material performance |
| Sigma Phase | Brittle intermetallic compound | Must be minimized |
| Chromium Nitrides | Potentially harmful precipitates | Can reduce corrosion resistance |
| Solution Annealing | Grade-specific heat treatment | Helps restore desired microstructure |
Key Microstructure Benefits
Strength & Toughness
A balanced microstructure provides high strength with good toughness.
Chloride SCC Resistance
The duplex microstructure helps resist chloride-induced stress corrosion cracking (SCC).
Pitting & Crevice Resistance
The alloy and phase balance support resistance to pitting and crevice corrosion.
Suitable Service Stability
A stable microstructure under appropriate conditions helps maintain performance in service.
Service Life Potential
The combined properties can support long service life in suitable applications.
Benefits depend on appropriate alloy selection, processing and operating conditions.
QUALITY ASSURANCE & INSPECTION
Quality Considerations
at Every Stage
A dependable super duplex steel casting requires controlled alloy chemistry, casting soundness, suitable solution heat treatment and verified ferrite–austenite balance. Inspection also addresses dimensions, surface condition and the requirements agreed with the customer.
A Systematic Approach to Reliable Castings
Comprehensive inspection and testing help ensure material integrity, dimensional accuracy and consistent performance in service.
Chemical Analysis
Verify chromium, nickel, molybdenum and other specified elements by suitable analysis; verify nitrogen using an appropriate analytical method.
Dimensional Inspection
Verify critical dimensions, profiles and fitting requirements; visually examine surfaces against the approved drawing and acceptance criteria.
Corrosion Resistance Testing
Grade-specific corrosion testing, including ASTM G48 where specified, using the agreed method, temperature and acceptance criteria.
Mechanical & Hardness Testing
Evaluate tensile strength, yield strength and elongation; carry out hardness and impact tests where required by the purchase specification.
Non-Destructive Testing
Dye penetrant, ultrasonic or radiographic testing as applicable, to detect surface and internal discontinuities.
Metallurgical Examination
Evaluate ferrite–austenite balance and harmful intermetallic phases or precipitates; review solution heat treatment and quenching records.
Identification & Traceability
Heat numbers and records according to the agreed documentation system, including relevant test reports and certificates.
Testing methods, sampling and acceptance criteria follow the selected casting standard and purchase specification. Required documentation may include material test certificates, chemistry and mechanical reports, heat-treatment records, phase-balance results and specified inspection reports.
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Super Duplex Steel Castings
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