AISI 321 (12Kh18N10T) vs AISI 316Ti (08Kh17N13M2T): Stabilized Stainless Steels
What is the difference between AISI 321 and AISI 316Ti?
Both are titanium-stabilized austenitic stainless steels. AISI 321 (Russian 12Kh18N10T) is an 18/10 grade with about 0.4% titanium added to prevent intergranular corrosion after welding. AISI 316Ti (Russian 08Kh17N13M2T) is the molybdenum-containing version (about 2.5% Mo) with titanium stabilization, combining the pitting resistance of 316 with stabilization. 316Ti is used where both chlorides and welding/sensitization are concerns.
AISI 321 (Russian grade 12Kh18N10T) and AISI 316Ti (Russian grade 08Kh17N13M2T) are titanium-stabilized austenitic stainless steels. Both were designed to resist intergranular corrosion after welding or exposure to the sensitization temperature range. 321 is an 18/10 chromium-nickel grade stabilized with titanium; 316Ti adds about 2.5% molybdenum to that stabilization, giving it the chloride pitting resistance of 316 plus immunity to sensitization. This article compares their composition, corrosion behaviour, welding and high-temperature use.
What is the chemical composition of AISI 321 (12Kh18N10T) vs AISI 316Ti (08Kh17N13M2T)?
| Element | AISI 321 (12Kh18N10T) | AISI 316Ti (08Kh17N13M2T) |
|---|---|---|
| C | ≤0.08 | ≤0.08 |
| Cr | 17.0–19.0 | 16.5–18.5 |
| Ni | 9.0–12.0 | 11.0–14.0 |
| Mo | — | 2.0–3.0 |
| Ti | ≥5×C (≈0.4–0.7) | ≥5×C (≈0.4–0.7) |
| Mn | ≤2.0 | ≤2.0 |
Key difference: 316Ti contains 2–3% molybdenum that 321 lacks. Both carry titanium at roughly 5× the carbon content to bind carbon and prevent sensitization.
What are the mechanical properties of AISI 321 (12Kh18N10T) vs AISI 316Ti (08Kh17N13M2T)?
| Property | AISI 321 | AISI 316Ti |
|---|---|---|
| Yield strength σ₀.₂, MPa | ≥205 | ≥215 |
| Tensile strength σᵦ, MPa | ≥515 | ≥515 |
| Elongation, % | ≥40 | ≥40 |
How corrosion resistant is AISI 321 (12Kh18N10T) vs AISI 316Ti (08Kh17N13M2T)?
| Medium | AISI 321 | AISI 316Ti | Recommendation |
|---|---|---|---|
| Intergranular corrosion (welded) | Excellent (stabilized) | Excellent (stabilized) | Both |
| Chloride pitting | Fair | Good (Mo) | 316Ti |
| General corrosion | Good | Good+ | 316Ti |
| High-temperature oxidation | Good to ~850°C | Good to ~900°C | Both |
4. Why Titanium Stabilization Matters
Titanium has a stronger affinity for carbon than chromium. By forming stable titanium carbides, it keeps carbon from precipitating as chromium carbides at grain boundaries during welding or heating in the 425–815°C (800–1500°F) range. Without stabilization, chromium depletion at the grain boundaries would cause intergranular corrosion (sensitization). This is why 321 and 316Ti are chosen over unstabilized 304/316 for welded structures in corrosive or high-temperature service.
5. Weldability
| Parameter | AISI 321 | AISI 316Ti |
|---|---|---|
| Welding methods | TIG, MIG, MMA | TIG, MIG, MMA |
| Recommended filler | ER321 | ER316L or ER316Ti |
| Post-weld heat treatment | Not required | Not required |
| HAZ sensitization | Avoided by Ti | Avoided by Ti |
6. High-Temperature Service
| Property | AISI 321 | AISI 316Ti |
|---|---|---|
| Continuous service limit, °C | ~850 | ~900 |
| Typical uses | Exhaust, heat exchangers | Exhaust, ducts, headers |
Where is AISI 321 (12Kh18N10T) vs AISI 316Ti (08Kh17N13M2T) used?
| Industry | AISI 321 | AISI 316Ti |
|---|---|---|
| Automotive / exhaust | Headers, manifolds | Headers, manifolds |
| Chemical / petrochemical | Welded tanks, piping | Welded tanks, chloride service |
| Aerospace | High-temp structures | High-temp structures |
| Power / heat exchangers | Superheater tubing | Superheater tubing |
8. Conclusion
Need 321 or 316Ti?
Shanghai Hangbo Alloy Group supplies AISI 321 (12Kh18N10T) and AISI 316Ti (08Kh17N13M2T) in sheet, plate, bar, pipe and forgings with EN 10204 3.1/3.2 certification. Send your welding and service conditions for a recommendation.
📧 Email: hangbo@nickel-alloy.com
📞 Tel: +86 13611656360
💬 WhatsApp: +86 13611656360
| Criterion | Choose 321 | Choose 316Ti |
|---|---|---|
| General stabilized service | ✓ Cost-effective | Slightly higher |
| Chloride / pitting risk | Fair | ✓ Better (Mo) |
| High-temp strength | Good | ✓ Better |
| Welded + corrosive | ✓ Stabilized | ✓ Stabilized |
Summary: Choose AISI 321 for general titanium-stabilized service where chlorides are absent. Choose AISI 316Ti when both molybdenum-level pitting resistance and titanium stabilization (for welded or high-temperature duty) are required.
Standards & References. Specifications cited on this page; confirm current revisions with the issuing body.
- ASTM A240/A312 — ASTM International
- EN 10204 — CEN / CENELEC (EN)
General references: Nickel Institute · AMPP (corrosion) · SAE International · ASTM International
9. Frequently Asked Questions (FAQ)
1. What is the difference between AISI 321 and 316Ti?
Both are titanium-stabilized austenitic stainless steels. 321 is an 18/10 grade; 316Ti adds about 2.5% molybdenum for chloride resistance while keeping titanium stabilization.
2. Why is titanium added?
Titanium binds carbon more strongly than chromium, preventing chromium carbide precipitation and intergranular corrosion in the 425–815°C range.
3. Which resists intergranular corrosion better?
Both are equal — both are titanium-stabilized. 316Ti additionally resists pitting better due to molybdenum.
4. Which has better high-temperature performance?
Both serve up to about 850–900°C; 316Ti retains slightly better strength because of molybdenum.
5. Are both weldable?
Yes. Both weld without post-weld heat treatment and avoid HAZ sensitization, making them preferable to unstabilized 304/316 in welded corrosive or high-temperature structures.
6. Which resists chloride pitting better?
316Ti, due to its 2.5% molybdenum, resists chloride pitting noticeably better than 321.
7. What standards cover these grades?
321: ASTM A240/A312/A276, UNS S32100, GOST 12Kh18N10T. 316Ti: ASTM A240/A312/A276, UNS S31635, GOST 08Kh17N13M2T.
8. In what forms are they supplied?
Both available as sheet, plate, bar, seamless/welded pipe, tube and forgings with EN 10204 certification.