AISI 304 Stainless Steel (UNS S30400): Properties & Equivalents vs AISI 316Ti Titanium-Stabilized Stainless Steel (UNS S31635)
Side-by-side engineering comparison of AISI 304 Stainless Steel (UNS S30400): Properties & Equivalents (ASTM A240/A276) and AISI 316Ti Titanium-Stabilized Stainless Steel (UNS S31635) (ASTM A240/A276). Compare mechanical properties, chemical composition, density, yield strength, international equivalents, and typical applications to select the right material for your project.
Quick Verdict
Choose 304 for general-purpose applications in mild environments — indoor architecture, food processing, and freshwater service — where its lower cost (25-40% less than 316) is justified. Choose 316 (316Ti) when the application involves chlorides, marine environments, chemical processing, or elevated temperatures above 400°C where 316's molybdenum provides critical pitting resistance and 316Ti's titanium stabilization preserves strength....
Cost-effectiveness in mild environments
Chloride/corrosion resistance and elevated-temperature stability
Quick Comparison
| Property | AISI 304 Stainless Steel | AISI 316Ti Titanium-Stabi |
|---|---|---|
| Standard | ASTM A240/A276 | ASTM A240/A276 |
| Category | Stainless Steel | Stainless Steel |
| Density | 8.00 g/cm³ | 8.00 g/cm³ |
| Yield Strength | 205 MPa (30 ksi) | 205 MPa (30 ksi) |
| Tensile Strength | 515 MPa (75 ksi) | 515 MPa (75 ksi) |
| Key Applications | AISI 304 (UNS S30400) is the most common austenitic stainless steel, containing 18-20% chromium and 8-10.5% nickel. This... | AISI 316Ti (UNS S31635) is the titanium-stabilized version of 316, with titanium added at 5×(C+N) minimum to prevent chr... |
International Equivalents
| AISI 304 Stainless S Equivalents | AISI 316Ti Titanium- Equivalents |
|---|---|
| EN 1.4301 | EN 1.4571 |
| X5CrNi18-10 | X6CrNiMoTi17-12-2 |
| SUS304 | SUS316Ti |
| 06Cr19Ni10 | 06Cr17Ni12Mo2Ti |
| AISI 304 | — |
How to Choose
| Choose AISI 304 Stainless Steel when... | SS304 is the economical 18-8 stainless for indoor, freshwater, and food-contact applications at 25-40% lower cost than 316. |
| Choose AISI 316Ti Titanium-Stabi when... | 316Ti adds 2-3% molybdenum for chloride pitting resistance and titanium stabilization for service above 400°C. |
Decision Checklist: Which Is Right for You?
| Criterion | AISI 304 Stainless S | AISI 316Ti Titanium- |
|---|---|---|
| Cost-Effectiveness In Mild Environments | ✓ | |
| Chloride/Corrosion Resistance And Elevated-Temperature Stability | ✓ | |
| Chloride exposure — 316Ti's PREN of 24-28 (vs 304's 18-20) is the sing... | ✓ | |
| Service temperature — above 400°C, 316Ti's Ti stabilization preserves ... | ✓ | |
| Cost premium — 316Ti costs 30-50% more than 304 due to molybdenum and ... | ✓ |
Selection Guide
Choose 304 for general-purpose applications in mild environments — indoor architecture, food processing, and freshwater service — where its lower cost (25-40% less than 316) is justified. Choose 316 (316Ti) when the application involves chlorides, marine environments, chemical processing, or elevated temperatures above 400°C where 316's molybdenum provides critical pitting resistance and 316Ti's titanium stabilization preserves strength. 316Ti costs 30-50% more than 304 but is essential in aggressive environments where 304 would fail prematurely.
Key Decision Factors
- Chloride exposure — 316Ti's PREN of 24-28 (vs 304's 18-20) is the single most important differentiator for marine, coastal, and chemical applications
- Service temperature — above 400°C, 316Ti's Ti stabilization preserves intergranular corrosion resistance; 304 sensitizes rapidly above 425°C
- Cost premium — 316Ti costs 30-50% more than 304 due to molybdenum and titanium additions; specifying 316Ti without chloride or high-temperature justification wastes budget
- Welding — 304 welds with ER308L; 316Ti welds with ER316L and benefits from Ti preventing HAZ sensitization in heavy sections without requiring the L-grade's low carbon
When to Use Each
Use AISI 304 Stainless S for:
304's 18-8 chromium-nickel composition handles indoor atmospheric exposure, food acids, and mild chemicals at 25-40% lower cost than 316Ti. Standard for kitchen equipment, sinks, and elevator interiors.
304 resists dilute nitric, sulfuric, and organic acids at moderate temperatures where chlorides are absent — the economical default for chemical drums and tanks.
304 is the most stocked and cheapest austenitic stainless grade, available in all forms (sheet, plate, bar, tube) for high-volume fabrication where 316's premium is not justified.
Use AISI 316Ti Titanium- for:
316Ti's 2-3% molybdenum provides pitting resistance (PREN 24-28 vs 18-20 for 304) essential for saltwater splash, coastal architecture, and offshore equipment.
Any stream containing chlorides, hydrochloric acid, or sodium hypochlorite requires 316Ti's Mo content to prevent pitting and chloride stress corrosion cracking above 60°C.
316Ti's titanium stabilization prevents carbide precipitation at sensitization temperatures, maintaining intergranular corrosion resistance in pressure vessels operating continuously above 400°C where 304 would sensitize.
Frequently Asked Questions
What is the main difference between AISI 304 Stainless Steel (UNS and AISI 316Ti Titanium-Stabilized?
AISI 304 Stainless Steel (UNS S30400): Properties & Equivalents (ASTM A240/A276) provides 205 MPa (30 ksi) yield strength at 8.00 g/cm³ density, while AISI 316Ti Titanium-Stabilized Stainless Steel (UNS S31635) (ASTM A240/A276) delivers 205 MPa (30 ksi) at 8.00 g/cm³. The choice depends on whether your application prioritizes cost-effectiveness in mild environments or chloride/corrosion resistance and elevated-temperature stability.
Can AISI 304 Stainless Steel (UNS be substituted for AISI 316Ti Titanium-Stabilized?
In many applications, these materials can be cross-referenced, but direct substitution should always be verified against specific project specifications, especially for cost-effectiveness in mild environments, chloride/corrosion resistance and elevated-temperature stability, and operating environment. Consult your engineer of record.
Can I use 304 instead of 316Ti to save cost?
Only if the environment is free of chlorides and service temperature stays below 425°C. 304 works for indoor, freshwater, and food-contact applications. In coastal areas (within 5km of saltwater), chemical plants handling chlorides, or pressure vessels operating above 400°C, 304 will pit, crack, or sensitize prematurely. The cost of replacing failed 304 components typically exceeds the 30-50% premium for 316Ti upfront.
What does the Ti in 316Ti do?
Titanium (added at 5×(C+N) minimum, typically 0.15-0.70%) preferentially bonds with carbon to form stable TiC carbides, preventing chromium carbide precipitation at grain boundaries during welding or service at 425-850°C. This preserves chromium in the matrix for corrosion resistance. 316Ti achieves sensitization resistance without the low-carbon approach of 316L, allowing higher carbon content for slightly better high-temperature strength.
Is 316Ti stronger than 304?
Slightly. 316Ti has 205 MPa minimum yield (vs 205 MPa for 304) — essentially identical at room temperature. The molybdenum in 316Ti provides modestly better high-temperature strength and creep resistance. The primary reason to choose 316Ti is corrosion resistance, not mechanical strength. For higher-strength stainless, consider duplex 2205 (450 MPa yield) or precipitation-hardening 17-4PH (725-1170 MPa yield).
Can 304 and 316Ti be welded together?
Yes, they are metallurgically compatible austenitic grades. Use ER309L or ER316L filler metal for the dissimilar weld. However, the weld zone will have corrosion resistance closer to 304 (the weaker grade). For critical applications, transition pieces or solid 316Ti is preferred to avoid creating a galvanic cell or corrosion weak point. Always verify filler selection with the WPS for the specific service environment.
What is PREN and why does it matter for this comparison?
PREN (Pitting Resistance Equivalent Number) = %Cr + 3.3×%Mo + 16×%N. It predicts resistance to chloride pitting. 304 has PREN ~18-20; 316Ti has PREN ~24-28. The 4-8 point difference is significant: in seawater (PREN >32 recommended), neither is adequate — consider duplex 2205 (PREN 34-36) or super-austenitic 904L (PREN 35+). But for moderate chloride exposure, 316Ti's PREN advantage over 304 is decisive.