316Ti Stainless Steel SA240 S31803 Duplex Comparison

316Ti Stainless Steel SA240 S31803 Duplex Comparison

Published: November 9, 2025 | Updated: November 9, 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 SA240/SA240M standards, comparing 316Ti (austenitic with Ti stabilization) and S31803 (duplex ferritic-austenitic) reveals key insights for applications balancing corrosion, strength, and cost.

As a premier producer and exporter based in China, Gangsteel has supplied thousands of tons of both 316Ti and 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 grades for a seawater system or chemical reactor where performance differences matter, this comparison breaks down their attributes. We'll analyze 316Ti (UNS S31635) and S31803 (Duplex 2205, UNS S31803), focusing on corrosion, mechanicals, and more, based on ASTM A240/A240M and ASME SA240/SA240M standards and our mill data.

From our production lines, we've seen the contrast: In a 2024 UAE desalination project, our S31803 duplex under ASTM A240 /A240M resisted pitting in chlorides better than 316Ti, but 316Ti's Ti stabilization provided superior IGC resistance at 60°C heat, as per client tests. Compliant with ASME SA240/SA240M for pressure apps, both have density ~8.00 g/cm³ but different PREN (23-28 for 316Ti vs. 33-35 for S31803). Let's compare in detail to guide your choice.

Summary

316Ti (austenitic) and S31803 duplex (ferritic-austenitic) under SA240 offer strong performance, but S31803's higher PREN (33-35 vs. 23-28) provides superior pitting/SCC resistance in chlorides, while 316Ti's Ti stabilization excels in high-temp IGC. S31803 has higher strength (yield 450 MPa vs. 205 MPa) for durability under stress, but 316Ti is more formable. Cost: S31803 20-40% higher ($3,500-4,500/ton vs. $3,200-3,800 FOB China 2025). Density similar (7.8-8.0 g/cm³). Choose S31803 for severe corrosives, 316Ti for high-heat acids. Gangsteel stocks both with certs.

Chemical Composition: Alloying Contrasts

Composition under ASTM A240/A240M and ASME SA240/SA240M defines their differences: S31803's high Cr/Mo/N for duplex phase, 316Ti's Ti for stabilization.

S31803's alloys give duplex phase for better corrosion; 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 in Expansion

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

S31803 more stable in thermal cycling.

Corrosion Resistance: S31803's Superiority in Aggressive Media

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-Corrosives

• 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 for Performance

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, ASME SA240 certs. Contact for comparisons.

FAQ: 316Ti Stainless Steel SA240 S31803 Duplex Questions Answered

Q: Is 316Ti stainless steel SA240 equivalent to S31803 duplex?

A: No, 316Ti (austenitic) is not equivalent to S31803 duplex (ferritic-austenitic)—different microstructures and properties, though both under SA240.

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

A: S31803 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 316Ti in SA240 specs?

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

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

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

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

A: S31803 superior in pitting/SCC (CPT 35-45°C vs. 25°C); 316Ti better for high-temp IGC with Ti.

Q: What is the price difference between 316Ti SA240 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, 316Ti SA240 or S31803?

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

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