EN 1.4404 Stainless Steel: Full Guide to Properties, Uses & Fabrication

If you need a stainless steel that resists corrosion—especially after welding—in harsh environments, EN 1.4404 stainless steel is the ideal choice. As the low-carbon version of EN 1.4401 (AISI 316), it’s trusted in industries like pharmaceuticals, marine, and food processing. This guide covers everything from its specs to real-world applications, helping you make informed decisions for your projects.

1. EN 1.4404 Stainless Steel: Overview & Key Specifications

Let’s start with the basics of EN 1.4404 stainless steel—its composition, standards, and core properties.

Chemical Composition

The EN 1.4404 composition is defined by its low carbon content (max 0.03%), which prevents intergranular corrosion. It also contains 16–18% chromium (corrosion resistance), 10–14% nickel (austenitic structure), and 2–3% molybdenum (enhanced chloride resistance). Small amounts of manganese (max 2.0%) and silicon (max 1.0%) complete the blend, creating a metal that balances strength and durability.

Industry Standards & Equivalents

EN 1.4404 follows strict global standards for consistency:

• 1.4404 AISI 316L equivalent: It’s the direct European counterpart to AISI 316L, so they’re interchangeable in most projects.
• 1.4404 UNS S31603: The Unified Numbering System identifier, used in North America.
• 1.4404 ASTM A240 / 1.4404 ASME SA-240: ASTM/ASME standards for plates/sheets, and 1.4404 EN 10088-2: European standard for flat products.

Physical & Mechanical Properties

Below is a table of critical properties that make EN 1.4404 stainless steel ideal for corrosion-sensitive applications:

Example: A pharmaceutical company uses EN 1.4404 stainless steel for drug storage tanks. Its low-carbon austenitic structure prevents intergranular corrosion, keeping drugs pure and meeting FDA standards.

2. Corrosion Resistance & Environmental Performance

EN 1.4404 stainless steel’s biggest advantage is its exceptional corrosion resistance—especially against intergranular and chloride-induced corrosion.

Key Corrosion Behaviors

• 1.4404 intergranular corrosion prevention: Its low carbon content stops carbide precipitation at grain boundaries, so it won’t corrode along grain edges—even after welding.
• 1.4404 chloride stress corrosion cracking immunity: Molybdenum and low carbon make it immune to stress corrosion cracking in chloride environments (e.g., saltwater, chemical tanks).
• 1.4404 PREN ~23–25: This high PREN rating means it resists pitting in harsh chloride settings, far better than EN 1.4307 (AISI 304L).
• 1.4404 seawater corrosion rate: Less than 0.1 mm/year in full seawater submersion—ideal for marine parts.

Critical Corrosion Considerations

• 1.4404 pitting corrosion resistance: Low risk in high-chloride environments (e.g., desalination plants), but avoid extreme concentrations (use super duplex grades for those).
• 1.4404 salt spray test ASTM B117: Shows minimal rust after 1000+ hours—far longer than EN 1.4301.
• 1.4404 sour service NACE MR0175: Approved for use in sour gas environments (high hydrogen sulfide), making it suitable for oil and gas equipment.
• 1.4404 vs 1.4401 sensitization: EN 1.4404 won’t “sensitize” (become prone to intergranular corrosion) after welding, unlike EN 1.4401 (which may need post-weld annealing).

Case Study: An offshore oil rig uses EN 1.4404 stainless steel for ballast systems. The metal’s chloride stress corrosion cracking immunity and seawater corrosion rate of <0.1 mm/year keep the system leak-free for 15+ years.

3. High-Temperature & Low-Temperature Properties

EN 1.4404 stainless steel performs reliably across a wide temperature range—from cryogenic to high heat.

High-Temperature Performance

• 1.4404 high-temperature strength: Maintains strength up to 750 °C, suitable for heat exchanger tubes and furnace parts.
• 1.4404 oxidation resistance up to 925 °C intermittent: Resists scaling when used intermittently at high temperatures (e.g., oven components).
• 1.4404 continuous service temperature: Safe for continuous use up to 700 °C—avoid higher temps to prevent strength loss.
• 1.4404 creep rupture data: At 700 °C and 100 MPa stress, it resists creep (slow deformation) for over 10,000 hours.

Low-Temperature Performance

• 1.4404 low-temperature toughness: Remains ductile at -196 °C (liquid nitrogen temperature), used for cryogenic vessels.
• 1.4404 impact energy at -196 °C: Absorbs over 60 J of energy, preventing brittle fracture in cold environments.
• 1.4404 cryogenic ductility: Retains 90% of its room-temperature ductility at -196 °C—critical for LNG (liquefied natural gas) equipment.

Thermal Properties

• 1.4404 thermal expansion coefficient: 16.5 × 10⁻⁶/°C (20–100 °C) — important for designing parts that handle temperature changes.
• 1.4404 thermal conductivity: 16.0 W/(m·K) at 100 °C — efficient heat transfer for heat exchangers.

4. Heat Treatment & Microstructure Stability

Proper heat treatment helps maintain EN 1.4404 stainless steel’s corrosion resistance and microstructure.

Common Heat Treatment Processes

Critical Considerations

• 1.4404 carbide precipitation avoidance: Its low carbon content makes carbide precipitation almost impossible—even if heat treatment is slightly off.
• 1.4404 austenitic grain size ASTM 5–8: Solution annealing keeps grains small, balancing strength and ductility.
• 1.4404 cold working strain hardening: Cold working (e.g., bending) increases hardness but doesn’t reduce corrosion resistance.
• 1.4404 magnetic permeability after cold work: May become slightly magnetic after heavy cold working, but this doesn’t impact performance.

Example: A heat exchanger manufacturer uses EN 1.4404 stainless steel for tubes. They solution anneal at 1050 °C to ensure carbide precipitation avoidance—tubes resist corrosion from hot coolants for 20+ years.

5. Welding, Fabrication & Machining Guidelines

EN 1.4404 stainless steel is easy to weld and fabricate, making it suitable for complex parts.

Welding Tips

• 1.4404 weldability rating: Excellent (rated 9/10)—works with TIG, MIG, and stick welding.
• 1.4404 no preheat required: Saves time compared to martensitic grades (e.g., 410).
• 1.4404 filler metal ER316L: Low-carbon filler matches the base metal’s corrosion resistance.
• 1.4404 interpass temperature 150 °C max: Prevents overheating and carbide formation.
• 1.4404 post-weld cleaning passivation: Nitric acid treatment boosts corrosion resistance by 40–50%.

Machining & Fabrication

• 1.4404 machining speeds and feeds: Use 120–180 m/min (turning) and 0.1–0.25 mm/rev—slower than EN 1.4301 due to molybdenum.
• 1.4404 tool life with coated carbide: Coated carbide tools (e.g., TiAlN) last 2–3x longer than uncoated tools.
• 1.4404 formability deep drawing: Good—its austenitic structure lets it be drawn into shapes like food processing bowls.
• 1.4404 distortion control techniques: Use balanced welding sequences and clamps to minimize warping.

Case Study: A brewery uses EN 1.4404 stainless steel for fermentation tanks. They weld tanks with ER316L filler and follow interpass temperature 150 °C max—tanks resist corrosion from beer acids and cleaning chemicals for 10+ years.

6. Product Forms, Sizes & Supply Chain

EN 1.4404 stainless steel is available in diverse forms to fit any project.

Common Product Forms

• 1.4404 stainless steel plate thicknesses: 3–200 mm (chemical reactors, offshore structures).
• 1.4404 sheet gauge chart: 26 gauge (0.45 mm) to 8 gauge (4.0 mm) (food equipment, surgical instruments).
• 1.4404 seamless pipe EN 10216-5: Sizes ½–24 inches (oil and gas piping, desalination plants).
• 1.4404 welded tube EN 10217-7: Sizes ½–12 inches (pharmaceutical piping, brewery lines).
• 1.4404 round bar stock: Diameters 5–300 mm (fasteners, marine hardware).
• 1.4404 custom forgings: For complex parts like valve bodies and offshore connectors.

Supply Chain Tips

• 1.4404 angle iron sizes: 20x20x3 mm to 100x100x10 mm (structural supports in coastal buildings).
• 1.4404 flat bar tolerances: ±0.1 mm for thickness—ideal for precision parts like surgical implants.
• 1.4404 hollow bar suppliers: Choose ISO 9001-certified suppliers for consistent wall thickness.
• 1.4404 mirror finish sheets: 0.5–5 mm thicknesses (architectural cladding, medical equipment).

7. Industry Applications & Case Studies

EN 1.4404 stainless steel is used in industries where corrosion resistance and hygiene are critical.

Key Applications

• 1.4404 pharmaceutical reactors: Handle drugs and solvents without corrosion—meet strict hygiene standards.
• 1.4404 brewery tanks: Store beer and wort without adding metallic tastes—resist acid corrosion.
• 1.4404 marine instrumentation tubing: Withstands saltwater corrosion for accurate data collection.
• 1.4404 offshore ballast systems: Prevent leaks in harsh marine environments.
• 1.4404 surgical implants ISO 5832-1: Biocompatible and corrosion-resistant—used for hip and knee implants.

Real-World Example: A medical device maker uses EN 1.4404 stainless steel for surgical implants. The metal meets 1.4404 surgical implants ISO 5832-1 standards, is biocompatible, and resists corrosion from bodily fluids—ensuring implants last 20+ years.

Yigu Technology’s Perspective on EN 1.4404 Stainless Steel

At Yigu Technology, we supply EN 1.4404 stainless steel to pharmaceutical, marine, and medical clients globally. Its low-carbon design and high PREN rating make it perfect for welded parts in harsh environments. We offer custom cuts (e.g., seamless pipe for desalination plants) and provide certification documents (EN 10088-2, ASTM A240) to meet industry standards. For medical clients, we ensure our EN 1.4404 meets ISO 5832-1, so their implants are safe and durable.

FAQ About EN 1.4404 Stainless Steel

1. Is EN 1.4404 stainless steel magnetic?
   No—unless it’s heavily cold-worked. Its 1.4404 low-carbon austenitic structure is non-magnetic, but heavy bending or stamping can make it slightly magnetic. This doesn’t affect corrosion resistance or strength.
2. When should I use EN 1.4404 instead of EN 1.4401?
   Use EN 1.4404 if your project involves welding. Its low carbon content ensures intergranular corrosion prevention, while EN 1.4401 may need post-weld annealing to avoid sensitization.
3. Can EN 1.4404 be used in sour gas environments?
   Yes! It’s approved under 1.4404 sour service NACE MR0175 for use in high-hydrogen sulfide environments (e.g., oil and gas wells). Its corrosion resistance prevents equipment failure in these harsh settings.