316Ti Stainless Steel SA240 S31803 Duplex Vs

316Ti Stainless Steel SA240 S31803 Duplex Vs

Published: November 12, 2025 | Updated: November 12, 2025By Gangsteel Engineering Team – 25+ Years in Stainless Steel Export Excellence

In the competitive landscape of stainless steels compliant with ASTM A240/A240M and ASME SA-240/SA-240M standards, comparing SA240 316Ti (titanium-stabilized austenitic) and SA240 S31803 (duplex ferritic-austenitic, also known as 2205) reveals key differences in corrosion resistance, strength, and suitability for aggressive environments like chlorides and high pressures.

As a premier producer and exporter based in China, Gangsteel has supplied thousands of tons of both SA240 316Ti and SA240 S31803 stainless steel, meeting ASTM A240/A240M specs for plates and sheets, to industries such as petrochemical, marine, and offshore.

If you're evaluating SA240 316Ti vs SA240 S31803 Duplex under ASME SA-240/SA-240M for a seawater system or chemical reactor where pitting, SCC, or high-temp durability is critical, this guide provides a clear, data-driven comparison. We'll break down their attributes, based on ASTM A240/A240M and ASME SA-240/SA-240M standards and our mill data.

From our production lines, we've seen the performance difference: In a 2024 UAE desalination facility, our SA240 S31803 Duplex plates under ASTM A240 /A240M resisted pitting in chlorides at 35-45°C CPT vs 25°C for SA240 316Ti, showing 40% better SCC resistance in seawater, as per client immersion tests. Compliant with ASME SA240/SA240M for pressure apps, S31803's PREN 33-35 vs 316Ti's 23-28 supports severe corrosives. Let's delve into SA240 316Ti vs S31803 Duplex, from composition to applications, to guide your choice.

Summary

SA240 316Ti and SA240 S31803 Duplex under ASTM A240/A240M and ASME SA-240/SA-240M are both excellent for corrosion, but S31803 Duplex's dual-phase structure (50% ferrite/50% austenite) provides superior pitting/SCC resistance (PREN 33-35 vs 23-28) in chlorides, with higher strength (yield 450 MPa vs 205 MPa). 316Ti's Ti stabilization excels in high-temp IGC (425-815°C) and is 20-40% cheaper ($3,200-3,800/ton vs $3,500-4,500 for S31803 FOB China 2025). Density ~8.00 g/cm³ for both. Choose S31803 for severe corrosives, 316Ti for heat. Gangsteel stocks both with certs for custom needs.

Chemical Composition: Phase and Alloy Differences

The compositions of SA240 316Ti and SA240 S31803 Duplex, as per ASTM A240/A240M and ASME SA-240/SA-240M, highlight S31803's higher Cr/Mo/N for duplex phase balance.

S31803's Cr/Mo/N promote 50/50 phase for strength; 316Ti's Ti focuses on heat stability.

Mechanical Properties: S31803's Strength Superiority

S31803 offers higher strength than 316Ti for durability.

S31803's dual phase improves durability in stress.

Physical Properties: Comparable with S31803 Edge

Both have similar physicals, but S31803's lower expansion aids stability.

S31803 more stable in thermal cycling.

Corrosion Resistance: S31803's Superiority

S31803 outshines 316Ti in most corrosives due to higher alloys.

• Pitting/Crevice: S31803 PREN ~35 vs. 23-28; CPT ~35-45°C vs. 25°C.
• IGC: Both resistant (316Ti Ti-stabilized, S31803 low C).
• SCC: S31803 better in chlorides/H2S.
• Uniform: S31803 <0.05 mm/year in acids; both good but S31803 in harsher.
• High-Temp: 316Ti better for IGC at 425-815°C; S31803 for general acid heat.

S31803 more corrosion-durable overall.

Weldability and Fabrication: 316Ti's Ease vs S31803's Care

316Ti welds easily without preheat; S31803 requires controlled heat to avoid phase imbalance. Both machinable, but S31803 harder.

Gangsteel's 316Ti SA240 Type 316Ti offers simpler fab.

Applications: S31803 for Severe, 316Ti for Heat

• Common: Chemical reactors (both durable).
• S31803 Specific: Offshore piping (chloride SCC resistance).
• 316Ti Specific: High-temp processing (IGC protection).

In Gangsteel's supply to U.S. oil, S31803 lasted longer in seawater.

Cost Comparison: S31803's Premium

In 2025, S31803 costs 20-40% more than 316Ti ($3,500-4,500/ton vs $3,200-3,800 FOB China) due to alloys, but saves on thickness/replacements.

Equivalents: Alternatives for Both

316Ti equivalents: EN 1.4571. S31803 equivalents: EN 1.4462. For A240 GR 316Ti, not interchangeable with S31803 in strength needs.

Sourcing from Gangsteel: Stock and Pricing

Gangsteel stocks 316Ti and S31803 at $3,200-3,800/ton (316Ti) and $3,500-4,500 (S31803) FOB. 1-200mm thick, certs. Contact for comparisons.

FAQ: SA240 316Ti vs S31803 Duplex Questions Answered

Q: How does corrosion resistance compare for SA240 316Ti and S31803 Duplex?

A: S31803 Duplex has superior pitting/SCC resistance (CPT 35-45°C vs 25°C for 316Ti) due to higher Cr/Mo; 316Ti better for high-temp IGC with Ti.

Q: What are the main differences between SA240 316Ti and S31803 Duplex?

A: S31803 Duplex has higher strength (yield 450 MPa vs 205) and PREN (35 vs 23-28) for better corrosion, but 316Ti's Ti stabilizes for high-temp IGC.

Q: Can I substitute S31803 Duplex for SA240 316Ti in specs?

A: Not directly—S31803 for severe corrosives/strength, 316Ti for high-temp IGC; check codes for equivalence.

Q: What is the density of SA240 316Ti vs S31803 Duplex?

A: SA240 316Ti 8.00 g/cm³; S31803 Duplex 7.80 g/cm³—S31803 lighter.

Q: How do mechanical properties compare for SA240 316Ti and S31803?

A: S31803 Duplex superior in strength (tensile 620 MPa vs 515, yield 450 vs 205); 316Ti more ductile (40% vs 25% elongation).

Q: What is the price difference between SA240 316Ti and S31803 in 2025?

A: S31803 20-40% higher ($3,500-4,500/ton vs $3,200-3,800 FOB China) due to alloys.

Q: Which is better for high-temperature apps, SA240 316Ti or S31803?

A: SA240 316Ti for IGC in 425-815°C; S31803 for general heat corrosives with higher strength.