Introduction
AISI 321 stainless steel is designed for use in applications where superior corrosion resistance is required. This material is widely used in chemical, food and drink, and other industries where the highest levels of resistance are required. It is also often found in fittings, valves, and pressure vessels due to its low permeability to liquids and gases. Furthermore, AISI 321 is resistant to heat aging, making it an ideal choice for applications where significant thermal cycling is expected.
Properties
AISI 321 stainless steel is an 18-10 chromium-nickel-titanium alloy with good weldability, toughness and formability. It has excellent corrosion resistance in a variety of environments, including neutral and basic solutions, organic acids, and in a wide range of atmospheric conditions.
The key property of AISI 321 is its superior corrosion resistance. It offers outstanding resistance to pitting and crevice corrosion in chloride-bearing environments, in addition to superior general corrosion resistance. Furthermore, 321 is particularly resistant to oxidation in the presence of sulfuric acid – making it ideal for food and drink processing equipment.
Fabrication and Forming
AISI 321 stainless steel can be fabricated using the same operations and processes as used for other austenitic stainless steels. It is well suited for welding and has excellent formability and machinability. Hot forming should be done in the temperature range of 1900-2200°F (1040-1205°C).
When cold forming AISI 321, it is recommended that tools should be designed for a slightly lower force than for austenitic stainless steels. Since 321 work hardens more rapidly than type 304 stainless steel, the tool must be able to react and adjust the forming speed to prevent cracking or tearing.
Heat Treatment
AISI 321 stainless steel is not heat treatable. However, it can be hardened by cold-working.
Uses
AISI 321 stainless steel is well suited for applications where the highest levels of corrosion resistance are needed. It is commonly used in the chemical, food and beverage, paper, and power industries. It is also used in non-oxidizing atmospheres wherever high-temperature strength and good corrosion resistance are required. Examples include boilers, pressure vessels, fittings, valves, and valves in oil refining, air-conditioning, and other equipment.
Conclusion
AISI 321 is a chromium-nickel-titanium austenitic stainless steel that offers superior levels of corrosion resistance when compared to other stainless steels in the same family. It is well suited for applications where the highest levels of corrosion resistance are required. It has excellent formability, weldability, and machinability, making it an ideal choice for applications where significant thermal cycling is expected.
