Comparison Of SUS316 And SUS316Ti: Standard Molybdenum-Containing Vs Titanium-Stabilized Molybdenum-Containing Austenitic Stainless Steel

SUS316 and SUS316Ti are 316 series austenitic stainless steels, with the core difference being that SUS316Ti adds titanium (Ti=4×C-0.70%) for stabilization. Titanium preferentially combines with carbon to form TiC, avoiding intergranular corrosion, while maintaining the molybdenum-containing corrosion resistance of the 316 series, making them suitable for different welding and high-temperature corrosion requirements.

Core Parameter Comparison

Parameter	SUS316 Stainless Steel	SUS316Ti Stainless Steel
Chemical Composition (wt%)	C≤0.08, Si≤1.00, Mn≤2.00, P≤0.045, S≤0.030, Cr=16.00-18.00, Ni=10.00-14.00, Mo=2.00-3.00, Fe=Balance	C≤0.08, Si≤1.00, Mn≤2.00, P≤0.045, S≤0.030, Cr=16.00-18.00, Ni=10.00-14.00, Mo=2.00-3.00, Ti=4×C-0.70, Fe=Balance
Mechanical Properties (Annealed)	Tensile Strength ≥515MPa, Yield Strength ≥205MPa, Elongation ≥40%, Hardness ≤217HB	Tensile Strength ≥515MPa, Yield Strength ≥205MPa, Elongation ≥40%, Hardness ≤217HB
Service Temperature	-196℃ to 870℃ (continuous service)	-196℃ to 900℃ (continuous service)
Equivalent Grades	EN 1.4401, UNS S31600, AISI 316	EN 1.4571, UNS S31635, AISI 316Ti

Key Performance Differences: 1. Intergranular corrosion resistance: SUS316Ti's titanium stabilization avoids the formation of Cr₂₃C₆ carbides, eliminating intergranular corrosion after welding or high-temperature service; SUS316 is prone to intergranular corrosion under the same conditions. 2. High-temperature performance: SUS316Ti's service temperature (900℃) is 30℃ higher than SUS316, with better high-temperature oxidation resistance. 3. Weldability: SUS316Ti has excellent welding stability, no post-weld heat treatment required; SUS316 needs post-weld annealing for harsh environments. 4. Machinability: SUS316Ti's titanium content increases cutting resistance, slightly worse machinability than SUS316. 5. Cost: SUS316Ti is 10-15% more expensive than SUS316.

Applicable Scenario Distinction: SUS316 is suitable for general medium-temperature, medium-corrosion components, such as chemical pipelines, food machinery, and marine hardware. SUS316Ti is suitable for high-temperature welding components and harsh corrosion environments, such as high-temperature heat exchanger tubes (800-900℃), boiler components, chemical reaction vessels (welding structure), and nuclear power plant auxiliary equipment.

Practical Q&A

Q1: What is the stabilization mechanism of titanium in SUS316Ti? A1: Titanium has a stronger affinity for carbon than chromium; at high temperatures or during welding, titanium preferentially combines with carbon to form TiC, avoiding the consumption of chromium to form Cr₂₃C₆ carbides, thus preventing the formation of chromium-depleted zones and eliminating intergranular corrosion.

Q2: Can SUS316Ti replace SUS316L in welding-intensive components? A2: Yes. Both have excellent intergranular corrosion resistance after welding; SUS316Ti has higher high-temperature performance than SUS316L, suitable for high-temperature welding components, while SUS316L is more suitable for low-temperature or general corrosion environments.

Q3: What welding materials are used for SUS316Ti? A3: Use ER316Ti welding wire; control welding heat input ≤180J/mm to avoid overheating; post-weld passivation treatment is recommended to further improve corrosion resistance, and no post-weld annealing is required.

Q4: What is the difference in service life between SUS316 and SUS316Ti in high-temperature environments? A4: At 850℃, SUS316Ti's service life (≥10 years) is twice that of SUS316 (≥5 years); SUS316's grain boundaries are prone to corrosion and embrittlement at high temperatures, while SUS316Ti maintains structural stability.

Q5: How to select between SUS316 and SUS316Ti? A5: Choose SUS316 if cost is a concern and the environment is mild (low-temperature, non-welding); choose SUS316Ti if high-temperature service (≥800℃) or welding-intensive components are required, and intergranular corrosion resistance is critical.