1. Overview
1.1 What is EN 1.4373 Stainless Steel?
EN 1.4373 is a high-performance austenitic stainless steel developed for extreme environments.
It is often referred to as 316H stainless steel in the U.S. (UNS S31630) due to its high carbon content (0.04–0.10%) and stabilized microstructure with additions of titanium (Ti) or niobium (Nb).
This alloy combines excellent corrosion resistance with high-temperature stability, making it ideal for applications requiring durability in aggressive chemical, thermal, and mechanical conditions.
1.2 Historical Context
The 200‑series austenitic steels emerged in the late 20th century to reduce reliance on nickel by substituting manganese and nitrogen, thereby offering a lower‑cost option with similar performance to 300‑series grades.
European standard EN 10088 first catalogued 1.4373 in its 2005 revision, formalizing its use in flat products for general corrosion‑resisting purposes.
1.3 Other International Equivalents
EN 1.4373 is recognized under multiple international standards, ensuring global consistency in material specifications:
| Standard | Grade | Country/Region |
|---|---|---|
| ASTM A240 | 202 (UNS S20200) | United States |
| JIS G4305 | SUS202 | Japan |
| GB/T 20878 | 12Cr18Mn9Ni5N | China |
| ISO 683-16 | – | Internationally Recognized |
| EN | 1.4373 | Europe |
1.4 Importance and Application Background
EN 1.4373 combines precipitation‑hardening capability with austenitic ductility, making it ideal for components demanding elevated strength without extreme corrosion environments.
Industries adopt it for equipment where reduced nickel content lowers cost volatility while maintaining adequate performance in food, architectural, and transportation sectors.
2. Basic Characteristics of EN 1.4373 Stainless Steel
2.1 Chemical Composition
The alloy’s performance hinges on its precise chemical makeup, carefully balanced to optimize strength, corrosion resistance, and formability.
Below is the composition range (in weight percentage):
| Element | Range (%) | Role in the Alloy |
|---|---|---|
| Carbon (C) | ≤0.15 | Enhances hardness but may form carbides if excessive |
| Silicon (Si) | ≤1.0 | Improves resistance to high-temperature oxidation |
| Manganese (Mn) | 7.5–10.5 | Stabilizes austenite and substitutes for nickel |
| Phosphorus (P) | ≤0.045 | Controls solidification and hot working behavior |
| Sulfur (S) | ≤0.015 | Minimizes brittleness; kept low for ductility |
| Chromium (Cr) | 17–19 | Forms protective chromium oxide passive film |
| Nickel (Ni) | 4–6 | Aids austenite stability and improves toughness |
| Nitrogen (N) | 0.05–0.25 | Increases strength without compromising ductility |
2.2 Physical Properties
Understanding EN 1.4373’s physical characteristics is crucial for thermal and structural design:
| Property | Value | Conditions |
|---|---|---|
| Density | 7.9 g/cm³ | Room temperature |
| Melting Range | 1398–1454°C | Standard atmosphere |
| Thermal Conductivity | 15 W/(m·K) | 20°C |
| Thermal Expansion Coefficient | 16.5×10⁻⁶/°C (20–100°C) | Linear expansion |
| Electrical Resistivity | 0.73 μΩ·m | 20°C |
| Magnetic Permeability | Non-magnetic (μ ≈ 1) | As-solutionized |
2.3 Mechanical Properties
| Property | Annealed Range |
|---|---|
| Tensile Strength (Rm) | 515 – 745 MPa |
| Yield Strength (Rp0.2) | ≥ 275 MPa |
| Elongation at Break | ≥ 40 % |
| Hardness (Rockwell B) | ≤ 95 HRB |
| These values demonstrate high strength coupled with good ductility for forming operations. |
2.4 Corrosion Resistance
EN 1.4373 excels in resisting general corrosion in atmospheric, fresh water, and many non-chloride aqueous environments.
In chloride environments, it performs moderately but falls short of 316‑grade resistance; designers specify more resistant alloys for marine or high‑salt settings .
The chromium-nitrogen combination forms a dense passive film that self-heals when minor surface damage occurs.
However, its resistance to chloride-induced pitting is lower than molybdenum-containing grades like 316L.
The steel tolerates dilute acids/alkalis but demands care in strong corrosive media to avoid pitting and stress‑corrosion cracking.
The Critical Pitting Temperature (CPT) for EN 1.4373 in 6% FeCl₃ solution is around 15–20°C, significantly lower than 316L (45–50°C).
3. Production and Processing of EN 1.4373 Stainless Steel
3.1 Production and Heat Treatment
3.1.1 Metallurgy and Casting
Manufacturers typically melt raw materials in an Electric Arc Furnace (EAF), then refine them in an Argon-Oxygen Decarburization (AOD) furnace to precisely regulate carbon and nitrogen content.
This process ensures precise chemical composition, critical for nitrogen-enhanced strength.
The molten steel is then cast into billets or slabs using continuous casting, ensuring uniform microstructure and minimal defects.
3.1.2 Forming Operations
- Hot Forging/Rolling: Billets are heated to 1050–1150°C to enhance malleability, then forged or rolled into intermediate products like bars, plates, or coils. Finishing temperatures must remain above 850°C to avoid excessive grain growth.
- Cold Forming: EN 1.4373’s high work-hardening rate allows complex cold-forming processes like stamping and deep drawing, though intermediate annealing may be necessary to prevent cracking.
3.1.3 Heat Treatment
- Solution Annealing: The alloy is heated to 1010–1150°C, held for 30–60 minutes, and quenched in water or air to dissolve precipitated phases and restore a homogeneous austenitic structure.
- Intermediate Annealing: After severe cold working, annealing at 1000–1050°C reduces work hardening and restores formability.
3.2 Fabrication and Finishing
3.2.1 Cutting and Machining
- Shearing: Suitable for thin sheets (≤3 mm), using sharp shears to ensure clean edges.
- Laser Cutting: Preferred for complex shapes, offering high precision and minimal heat-affected zones.
- Plasma Cutting: Effective for thicker materials (≥5 mm), though post-cut grinding may be needed to remove oxidization.
3.2.2 Welding
EN 1.4373 can be welded using TIG, MIG, and resistance welding methods. Key considerations include:
- Filler Materials: Use ER202 (matching composition) or ER308L (for improved corrosion resistance in non-critical applications).
- Preheating: Not required for most applications, but ensure the base metal is clean to prevent contamination.
- Post-Weld Treatment: Solution annealing is recommended for critical components to eliminate residual stress.
3.2.3 Forming and Stamping
The alloy’s high work-hardening rate makes it suitable for processes like stamping and roll forming.
However, multiple annealing steps may be necessary for complex shapes to avoid cracking.
3.2.4 Surface Treatment
- 2B Finish: A smooth, slightly reflective surface obtained by cold rolling and annealing.
- Mirror Polish (8K): Achieved through mechanical polishing, ideal for architectural decorative elements.
- Electropolishing: Enhances corrosion resistance by removing surface contaminants.
4. Application Areas of EN 1.4373 Stainless Steel
EN 1.4373 stainless steel, also known as AISI 202, is a versatile austenitic stainless steel that combines good corrosion resistance with cost-effectiveness.
Its unique properties make it suitable for various industries. Below is an in-depth exploration of its application areas:
4.1 Food and Beverage Industry
The food and beverage sector demands materials that ensure hygiene, resist corrosion, and withstand various processing conditions.
EN 1.4373 stainless steel meets these requirements effectively.
Key Applications:
- Processing Equipment: Used in manufacturing mixers, blenders, and conveyors due to its durability and ease of cleaning.
- Storage Tanks: Ideal for storing dairy, juices, and other beverages, ensuring product purity.
- Piping Systems: Employed in transporting liquids, benefiting from its corrosion resistance.
- Kitchen Utensils: Commonly used in cutlery, pots, and pans, offering both functionality and aesthetic appeal.
4.2 Household Appliances
EN 1.4373 in Appliances: Manufacturers prefer this stainless steel grade for its optimal performance-cost balance in household products.
Common Uses:
- Kitchen Appliances: Utilized in the exteriors of refrigerators, dishwashers, and ovens for its sleek appearance and resistance to fingerprints.
- Cookware: Employed in manufacturing durable and corrosion-resistant pots, pans, and utensils.
- Sinks and Faucets: Chosen for its ability to withstand constant exposure to water and cleaning agents.
4.3 Building and Decoration Applications
EN 1.4373 stainless steel finds extensive use in construction and decorative elements due to its formability and visual appeal.
Applications:
- Architectural Trim: Used in window frames, door handles, and decorative panels.
- Handrails and Balustrades: Provides safety features with a polished look.
- Cladding: Applied to building exteriors for a modern facade.
4.4 Automotive Industry
The automotive sector benefits from EN 1.4373 stainless steel’s strength and corrosion resistance.
Key Uses:
- Exhaust Systems: Handles high temperatures and corrosive gases effectively.
- Trim and Molding: Adds aesthetic value while resisting environmental wear.
- Structural Components: Utilized in brackets, frames, and supports for its strength-to-weight ratio.
4.5 Industrial Equipment
EN 1.4373 Stainless Steel in Industry: Manufacturers select this grade for critical equipment demanding exceptional durability and multi-chemical resistance.
Applications:
- Chemical Processing Equipment: Resists corrosion from mild chemicals and solvents.
- Storage Vessels: Suitable for holding various industrial liquids.
- Machinery Components: Used in parts that experience wear and require longevity.
4.6 Building and Construction
Beyond decorative uses, EN 1.4373 stainless steel plays a role in structural applications within the construction industry.
Uses:
- Structural Frameworks: Provides support in buildings and infrastructure projects.
- Reinforcements: Used in concrete structures to enhance strength and durability.
- Fasteners and Connectors: Ensures long-lasting joints and connections.
EN 1.4373 stainless steel’s versatility across these application areas underscores its value in industries seeking a balance between performance, aesthetics, and cost.
5. Advantages and Disadvantages of EN 1.4373 Stainless Steel
5.1 Advantages
- Cost-Effective: Reduced nickel content lowers material costs by 10–15% compared to 304.
- High Strength: Tensile strength ≥515 MPa, suitable for load-bearing applications.
- Good Formability: Cold-formable into complex shapes, ideal for stamping and rolling.
- Corrosion Resistance: Comparable to 304 in non-chloride environments.
- Non-Magnetic: Austenitic structure ensures non-magnetic properties.
5.2 Limitations
- Limited Chloride Resistance: Susceptible to pitting in high-chloride environments (e.g., seawater).
- Lower High-Temperature Resistance: Not suitable for continuous service above 800°C.
- Work-Hardening Challenges: Requires frequent annealing during cold working.
- Weldability Considerations: Proper technique and post-weld treatment are necessary.
5.3 Alternative Grades
| Alloy | Key Advantages | Best Suited For |
|---|---|---|
| 304 (1.4301) | Superior chloride resistance, wider temperature range | General corrosion applications |
| 316 (1.4401) | Excellent resistance to chlorides and crevice corrosion | Marine environments |
| 2205 Duplex | High strength and corrosion resistance | High-stress applications |
| 201 (1.4372 Stainless Steel) | Lower cost but lower strength | Less demanding forming operations |
6. Comparison with Other Stainless Steel Alloys
| Property | 1.4373 (202) | 1.4372 (201) | 304 (1.4301) | 316 (1.4401) | 317L (1.4581) | 2205 Duplex |
|---|---|---|---|---|---|---|
| Nickel (Ni, %) | 4–6 | 3.5–5.5 | 8–10.5 | 10–14 | 12–15 | 4.5–6.5 |
| Manganese (Mn, %) | 7.5–10.5 | 5.5–7.5 | ≤2.0 | ≤2.0 | ≤2.0 | ≤2.0 |
| Molybdenum (Mo, %) | – | – | – | 2–3 | 3–4 | 2.5–3.5 |
| Nitrogen (N, %) | 0.05–0.25 | 0.05–0.25 | ≤0.10 | ≤0.10 | 0.1–0.22 | 0.08–0.20 |
| Chromium (Cr, %) | 17–19 | 16–18 | 18–20 | 16–18 | 18–20 | 21–23 |
| Tensile Strength (MPa) | ≥515 | ≥635 | ≥515 | ≥515 | ≥485 | ≥620 |
| Yield Strength (Rp0.2, MPa) | ≥205 | ≥245 | ≥205 | ≥205 | ≥175 | ≥450 |
| Critical Pitting Temp (CPT, °C) | 15–20 | 20–25 | 30–35 | 45–50 | 60–70 | 30–40 |
| Density (g/cm³) | 7.9 | 7.93 | 7.93 | 8.0 | 8.0 | 7.8 |
| Cost (Relative) | 1.0 (Base) | 0.95 | 1.2–1.3 | 1.5–1.8 | 2.0–2.5 | 1.8–2.2 |
| Magnetic Behavior | Non-magnetic | Non-magnetic | Non-magnetic | Non-magnetic | Non-magnetic | Ferritic-austenitic (slightly magnetic) |
Practical Selection Guide
| Application Scenario | Recommended Alloy | Key Rationale |
|---|---|---|
| General-purpose, non-critical, low cost | 1.4373 (202) / 1.4372 (201) | Balances cost, formability, and moderate corrosion resistance in mild environments. |
| General corrosion resistance (non-chloride) | 304 (1.4301) | Proven performance in food, pharmaceuticals, and atmospheric conditions. |
| Chloride-rich environments (e.g., marine) | 316 (1.4401) / 317L (1.4581) | Molybdenum enhances pitting resistance; 317L for extreme chloride/heat. |
| High-strength, moderate-corrosion | 2205 Duplex | Dual-phase structure provides high strength and resistance to SCC in coastal/industrial settings. |
| Decorative, formable components | 1.4373 (202) | Excellent polishability and cost-effectiveness for architectural/consumer |
7. EN 1.4373 Stainless Steel Products Offered by Langhe
Langhe supplies a full range of EN 1.4373 forms:
- Sheets & Plates (cold‑rolled 2B, BA, No. 1)
- Bars (round, flat, square, hexagonal)
- Wire (drawn, annealed, bright products)
- Tubes & Pipes (welded and seamless, standard and custom sizes)
- Fittings & Flanges (available on request, typical materials in 304/316 but 1.4373 can be supplied)
8. Relevant Standards and Certifications
8.1 European Standards
- EN 10088-2: General requirements for corrosion-resistant steels.
- EN 10088-3: Technical delivery conditions for semi-finished products, bars, and rods.
8.2 International Standards
- ASTM A240: Specification for pressure vessels and general applications.
- JIS G4305: Cold-rolled stainless steel plates and sheets.
8.3 Verification and Testing
- Chemical Analysis: Optical emission spectroscopy to confirm composition.
- Mechanical Testing: Tensile, impact, and hardness tests.
- Corrosion Tests: Intergranular corrosion (ASTM A262) and pitting corrosion (ASTM G48).
- Environmental Compliance: RoHS and REACH regulations.
9. FAQ
9.1 Is EN 1.4373 Stainless Steel Magnetic?
No, in its as-solutionized state, EN 1.4373 is non-magnetic.
Severe cold working can introduce slight magnetism, but annealing fully restores non-magnetic properties.
9.2 Can EN 1.4373 be used in marine environments?
While it resists mild marine atmospheres, it is not recommended for direct seawater contact.
Use 316L or duplex stainless steels for marine applications.
9.3 What welding methods are suitable for EN 1.4373?
TIG or MIG welding with ER202 filler wire is recommended.
Post-weld solution annealing is advisable for critical components.
9.4 How does EN 1.4373 compare to 304 in food applications?
Both are suitable for food contact, but EN 1.4373 offers comparable corrosion resistance at a lower cost.
For high-purity applications, 304 may be preferred.
9.5 Can EN 1.4373 be heat-treated to increase hardness?
Standard heat treatment softens the alloy. Hardness is primarily increased through cold working.
10. Conclusion
EN 1.4373 stainless steel delivers a compelling blend of high strength, good formability, and economical alloying.
Its austenitic matrix and precipitation‑hardening potential serve industries from food processing to architecture.
While it does not match the extreme corrosion resistance of 316, its reduced nickel content and robust mechanical profile offer designers a versatile, cost‑effective solution for moderately corrosive and high‑strength applications.
Understanding its composition, processing routes, and certification pathways ensures optimal deployment and performance in diverse engineering contexts.