Introduction
AISI 321/1Cr18Ni11Ti (UNS S32161) stainless steel, named by its chemical composition of 1Cr18Ni11Ti, is a titanium-stabilized austenitic stainless steel. It contains 18% chromium, 11% nickel and titanium as the stabilizing element. At a certain temperature range, the titanium can expand austenite grains, improve the resistance to intergranular corrosion, and creep resistance of steels. AISI 321/1Cr18Ni11Ti stainless steel has good corrosion resistance, high temperature strength and good resistance to intergranular corrosion, compared with 304 stainless steel. Therefore, AISI 321/1Cr18Ni11Ti stainless steel has become an ideal material in the production of high temperature parts such as exhaust manifolds, turbine blades and fasteners.
AISI 321/1Cr18Ni11Ti stainless steel is widely used in parts and components exposed to chemical medium such as acetic acid, phosphoric acid, formic acid and urea. It is also widely used in parts and components exposed to stronger alkaline medium and organic acid medium, such as seawater, atmospheres containing moderate amounts of oxidizing or reducing gases and various organic chemicals. Its excellent corrosion resistance and uniformity make it suitable for valve and pump components, fasteners, structural parts and springs.
AISI 321/1Cr18Ni11Ti stainless steel has good oxidation resistance and creep resistance. Its high temperature strength and oxidation resistance make it suitable for operation in 500-900°C air or in temperatures up to 800°C in an oxidizing or inert atmosphere. It can also be used at temperatures of 550-700°C in oxidising media, and at 800-900°C in reducing media. Its good diffusion resistance at high temperatures makes it suitable for components in jet engines and high temperature exhaust systems.
At constant temperatures, AISI 321/1Cr18Ni11Ti stainless steel also has good workability, with high plasticity, considerable tensile strength and good ductility. It can be processed by cold rolling and drawing, and by hot rolling and forging. AISI 321/1Cr18Ni11Ti stainless steel can also be welded but the joint must be annealed after welding to prevent intergranular corrosion.
Microstructure of AISI 321/1Cr18Ni11Ti stainless steels consists of austenitic grains, low intergranular content and a small amount of TiN particles. It has excellent corrosion resistance, It resists intergranular corrosion and chloride stress corrosion cracking, and it is more resistant to pitting corrosion and crevice corrosion than 304 stainless steel.
Conclusion
AISI 321/1Cr18Ni11Ti stainless steels, with a titanium content of 0.15-0.75%, has a great advantage compared with 304 stainless steel. Its titanium-stabilized austenitic structure gives it better corrosion resistance under a wide range of temperatures and pH values. It is an ideal material for producing high-temperature parts such as exhaust manifolds, turbine blades and fasteners. It has good workability and weldability, and is an excellent choice for fasteners, valves and pumps, and for other components exposed to chemcial or corrosive environments. Its high temperature strength and oxidation resistance make it suitable for operation in 500-900°C air or in temperatures up to 800°C in an oxidizing or inert atmosphere. It has also excellent corrosion resistance and uniformity, which are suitable used in structual parts and springs.
