316Ti vs 321 Stainless Steel High-Temp Performance Analysis

 

 

 

316Ti vs 321 Stainless Steel: High-Temp Performance Analysis

Published: November 8, 2025 | Updated: November 8, 2025By Gangsteel Engineering Team – 25+ Years in Stainless Steel Export Excellence

In the high-stakes world of stainless steels for elevated-temperature applications, 316Ti and 321 grades often compete for selection in industries facing thermal cycling and corrosive challenges.

As a premier producer and exporter based in China, Gangsteel has supplied thousands of tons of both 316Ti and 321 stainless steel in forms like plates, sheets, and bars to sectors such as petrochemical, aerospace, and power generation.

If you're evaluating materials for a boiler component or exhaust system where high-temp performance is paramount, understanding their differences in stability, strength retention, and corrosion resistance is vital. This analysis compares 316Ti and 321 head-to-head, focusing on high-temperature behavior, based on industry standards and our mill experience.

From our production insights, 321 has long been a staple for its titanium stabilization, but 316Ti's added molybdenum gives it an edge in combined heat and chloride exposure: In a 2024 U.S. power plant retrofit, our 316Ti tubes endured 700°C steam with acids, showing 20% less oxidation than 321, as per client inspections. Both are austenitic SS under ASTM A240 /A240M for plates, but their stabilizers—titanium in both, but 316Ti with Mo—define their high-temp niches. Let's dissect the analysis, from composition to real-world durability, to guide your choice.

 

Summary

316Ti and 321 stainless steels are both titanium-stabilized austenitic grades designed for high-temperature service, preventing intergranular corrosion (IGC) through carbide stabilization. 316Ti, with added molybdenum (2-3%), offers superior pitting and crevice resistance in chlorides (PREN 23-28), making it more durable in mixed corrosive-heat environments like marine exhausts.

321 relies on higher titanium for similar IGC protection but lacks Mo, limiting its pitting durability (PREN ~18-20). Both have tensile strength around 515 MPa and density ~8.00 g/cm³, but 316Ti retains better creep strength above 600°C. 316Ti is 10-20% pricier but excels in aggressive apps; 321 is cost-effective for general high-heat. Gangsteel stocks both under ASME SA240/SA240M for pressure compliance.

 

Chemical Composition: Stabilizers and Alloying Differences

The compositions of 316Ti and 321 are similar austenitic bases, but 316Ti's molybdenum addition enhances corrosion, while both use titanium for high-temp stabilization.

Standard composition (per ASTM A240, % by weight):

Element	316Ti (UNS S31635)	321 (UNS S32100)	Impact on High-Temp Performance
Carbon (C)	0.08 max	0.08 max	Low in both to reduce carbide risk; Ti binds remaining C.
Manganese (Mn)	2.00 max	2.00 max	Identical; no high-temp impact.
Silicon (Si)	0.75 max	0.75 max	No difference; aids oxidation resistance at heat.
Phosphorus (P)	0.045 max	0.045 max	Identical impurity control.
Sulfur (S)	0.030 max	0.030 max	No difference.
Chromium (Cr)	16.00-18.00	17.00-19.00	Slightly higher in 321 for oxidation; both form passive films.
Molybdenum (Mo)	2.00-3.00	-	Mo in 316Ti boosts high-temp pitting (PREN 23-28 vs. 18-20 for 321).
Nickel (Ni)	10.00-14.00	9.00-12.00	Higher in 316Ti for austenite stability at heat.
Titanium (Ti)	5x(C+N) min, 0.70 max	5xC min, 0.70 max	Ti in both prevents IGC; 316Ti includes N in calc for better binding.
Nitrogen (N)	0.10 max	Not specified	Minor in 316Ti for strength.
Iron (Fe)	Balance	Balance	Base matrix.

316Ti's Mo gives it better high-temp durability in mixed corrosives, while 321's higher Cr aids pure oxidation.

 

Mechanical Properties: Similar Strength, Better Heat Retention for 316Ti

Both grades have comparable room-temp strength, but 316Ti's Mo and Ti improve high-temp creep and rupture.

Property	316Ti Min	321 Min	Key Difference
Tensile Strength (MPa)	515	515	Identical; 316Ti better at >600°C due to Mo/Ti.
Yield Strength (MPa)	205	205	No difference.
Elongation (%)	40	40	Equivalent for forming.
Hardness (HRB max)	95	95	No difference.
Impact Toughness (J)	~100 at RT	~100 at RT	Similar; both good at low temps.

316Ti's creep strength is higher, making it more durable in sustained loads at heat.

 

Physical Properties: Comparable but with Heat Edge for 316Ti

Both have similar physicals, but 316Ti's Ti improves high-temp stability.

Property	316Ti Value	321 Value	Notes
Density (g/cm³)	8.00	7.93	316Ti slightly denser due to Mo.
Thermal Conductivity (W/m·K at 100°C)	14.6	15.0	Minor difference.
Specific Heat (J/kg·K)	500	500	Identical.
Thermal Expansion (10^-6 /°C, 20-100°C)	16.5	16.6	Low for both.

316Ti's lower expansion enhances durability in thermal cycling.

 

Corrosion Resistance: 316Ti's Enhanced Durability in Combined Threats

Both resist general corrosion, but 316Ti's Mo provides better pitting, while both Ti stabilizers prevent IGC.

• Pitting/Crevice: 316Ti superior with Mo (PREN 23-28 vs. 18-20 for 321); CPT ~25°C vs. 15°C.
• IGC: Both resistant per A262; Ti effective in high-heat.
• SCC: 316Ti better in chlorides due to Mo; both good but 316Ti durable post-heat.
• Uniform: <0.1 mm/year in dilute acids for both; similar in boiling acetic.

316Ti is more durable for high-heat with corrosives like marine exhausts.

 

Weldability and Fabrication: Comparable with Stabilization Benefits

Both weld well with ER316L fillers; no preheat. Both Ti stabilizers eliminate post-weld annealing for IGC, but 316Ti's Mo adds no fab difference. Machinability ~60% of carbon steel for both.

Gangsteel's 316Ti SA240 Type 316Ti welds without sensitization.

 

Applications: Where Each Excels

• Common: Architectural, food equipment (both durable).
• 316Ti Specific: High-temp chemical processing (Mo for pitting).
• 321 Specific: Aerospace exhausts (higher Cr for oxidation).

In Gangsteel's supply to U.S. power, 316Ti lasted longer in chlorinated heat.

 

Equivalents: Alternatives for Both

316Ti equivalents: UNS S31635, EN 1.4571. 321 equivalents: UNS S32100, EN 1.4541. For A240 GR 316Ti, it's not interchangeable with 321 in chloride-heavy heat.

 

Sourcing from Gangsteel: Stock and Pricing

Gangsteel stocks 316Ti and 321 at $3,200-3,800/ton FOB (similar pricing). 1-200mm thick, ASME SA240 certs. Contact for comparisons.

 

FAQ: 316Ti vs 321 Stainless Steel Questions Answered

Q: How does high-temperature performance differ between 316Ti and 321 stainless steel?

A: Both excel at high temps with Ti stabilization against IGC, but 316Ti's Mo provides better pitting in chlorides at heat (PREN 23-28 vs. 18-20), making it more performant in combined corrosive-heat like marine boilers.

Q: Which has better creep resistance, 316Ti or 321?

A: 316Ti has superior creep and stress rupture at >600°C due to Mo strengthening, while 321's higher Cr aids oxidation but less in mixed corrosives.

Q: What are the key composition differences affecting high-temp performance?

A: 316Ti has Mo (2-3%) for pitting at heat, while 321 has higher Cr (17-19%) for oxidation; both Ti stabilizers prevent IGC, but 316Ti's balance is better for chloride-high heat.

Q: Is 316Ti or 321 better for high-temperature corrosion resistance?

A: 316Ti for high-temp with corrosives (Mo for PREN); 321 for pure oxidation (higher Cr). 316Ti rate <0.1 mm/year in dilute acids at 600°C vs. 321's similar but weaker in chlorides.

Q: How do mechanical properties at high temperatures compare for 316Ti and 321?

A: Both retain ~70% strength at 815°C, but 316Ti's Mo improves creep (100,000-hr rupture ~100 MPa at 600°C vs. 90 MPa for 321).

Q: What is the maximum temperature for 316Ti vs 321 stainless steel?

A: Both up to 815°C for intermittent, 650°C continuous; 316Ti better in corrosive heat, 321 in dry oxidation.

Q: Can I substitute 321 for 316Ti in high-temp apps?

A: Yes for oxidation-focused; no for chloride/acid heat where 316Ti's Mo is essential. Dual-cert from Gangsteel eases swaps.