SUS316Ti Stainless Steel

SUS316Ti is a titanium-stabilized austenitic stainless steel derived from SUS316, designed to eliminate sensitization and enhance intergranular corrosion resistance during high-temperature processing. It retains SUS316's excellent corrosion resistance in harsh environments like chloride-containing media while boasting better thermal stability, making it ideal for applications involving repeated heating and cooling cycles.

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, Ti = 5×C–0.70, Fe = Balance.

Mechanical Properties (Annealed): Tensile Strength ≥ 520 MPa, Yield Strength ≥ 205 MPa, Elongation ≥ 40%, Hardness (HB) ≤ 217.

Performance Advantages: Superior intergranular corrosion resistance vs. SUS316; high tensile and creep strength at elevated temperatures; good weldability without post-weld heat treatment; excellent resistance to pitting and crevice corrosion in saltwater.

Equivalent Grades: ASTM A240 316Ti, EN 1.4571, UNS S31635.

Applications: Chemical processing equipment, heat exchangers, marine components, exhaust systems, pharmaceutical machinery, and pulp and paper industry digesters.

FAQ

Q: Why is titanium added to SUS316Ti?A: Titanium is added to bind with carbon in the steel, preventing the formation of chromium carbides at grain boundaries during heating. This process eliminates sensitization, a common issue in non-stabilized grades like SUS316, which leads to intergranular corrosion when exposed to corrosive environments after welding or high-temperature use. Without titanium, chromium depletes near grain boundaries, making the steel vulnerable to rusting in aggressive media. The addition of titanium ensures that the steel maintains its corrosion resistance even after prolonged high-temperature service, which is critical for applications such as heat exchangers and chemical reactors. This stabilization also allows SUS316Ti to be used in thicker sections without the need for post-weld heat treatment, reducing production costs and time.

 

Q: Can SUS316Ti be used in seawater applications?A: Yes, SUS316Ti is well-suited for seawater applications due to its high molybdenum content and titanium stabilization. Molybdenum enhances the steel's resistance to pitting and crevice corrosion, which are common failure modes in chloride-rich environments like seawater. Unlike carbon steel or lower-grade stainless steels, SUS316Ti does not suffer from rapid corrosion when exposed to saltwater, making it ideal for marine components such as boat fittings, offshore platform parts, and seawater cooling systems. Its ability to withstand both immersion and splash zones ensures long-term durability in harsh marine conditions. Additionally, the steel's good mechanical strength allows it to handle the mechanical stresses associated with marine operations, such as wave impact and structural loads.

 

Q: What is the maximum operating temperature for SUS316Ti?A: SUS316Ti can operate continuously at temperatures up to 870°C in oxidizing atmospheres, making it suitable for high-temperature applications like exhaust manifolds and industrial furnaces. At temperatures above this threshold, the steel may experience a gradual loss of strength due to grain growth and oxidation, but it still performs better than non-stabilized grades like SUS316. In reducing atmospheres, the maximum operating temperature is slightly lower, around 760°C, to avoid carbide precipitation and embrittlement. The titanium stabilization helps maintain the steel's structural integrity at high temperatures by preventing chromium depletion, ensuring that it retains its corrosion resistance and mechanical properties even after extended exposure to heat. This high-temperature stability makes SUS316Ti a preferred choice for heat treatment equipment and power generation components.

Q: How does SUS316Ti compare to SUS316 in terms of weldability?A: SUS316Ti has better weldability than SUS316, especially when it comes to post-weld corrosion resistance. Both grades can be welded using standard methods like TIG, MIG, and SMAW, but SUS316 requires post-weld heat treatment to restore its corrosion resistance in most cases, while SUS316Ti does not. The titanium in SUS316Ti binds with carbon during welding, preventing the formation of chromium carbides at grain boundaries in the heat-affected zone (HAZ). This eliminates the need for post-weld annealing, which saves time and reduces costs in manufacturing processes. Additionally, the HAZ of SUS316Ti welds retains its corrosion resistance, whereas the HAZ of SUS316 welds is prone to intergranular corrosion without heat treatment. This makes SUS316Ti a more practical choice for welded structures that cannot be heat-treated after fabrication, such as large pressure vessels and piping systems.

 

Q: Is SUS316Ti suitable for food and pharmaceutical applications?A: Yes, SUS316Ti is approved for use in food and pharmaceutical applications due to its excellent corrosion resistance and non-toxicity. The steel does not leach harmful substances into food or pharmaceutical products, making it safe for use in processing equipment, storage tanks, and packaging machinery. Its resistance to organic acids, such as those found in fruit juices and dairy products, ensures that it does not corrode or contaminate the products it comes into contact with. In the pharmaceutical industry, SUS316Ti is used for manufacturing reactors, centrifuges, and sterile processing equipment, where cleanliness and corrosion resistance are critical. The steel's smooth surface finish can be easily cleaned and sterilized, meeting the strict hygiene standards required by food and drug regulatory bodies. Additionally, its durability and low maintenance requirements make it a cost-effective choice for these industries.