Austenitic stainless steel, or alloy 321, is a family of alloys renowned for their ductility, mechanical attributes, and corrosion resistance. Titanium stabilizes type 321 stainless steel, making it resistant to chromium carbide precipitation at temperatures above 800° F.
Alloy 321 satisfies the stringent quality requirements of the pharmaceutical and biochemical industries. It can be used to make reaction vessels, storage tanks, pumps, piping systems or heat exchangers, ovens, fittings, or valves. Because of this, 321 stainless steel is regarded as the best type of building material for use in the pharmaceutical business, where hygiene, strength, and durability are important considerations.
321 grades stainless steel tube offer stronger creep and stress rupture properties than SS 304 and 304L, and it retains oxidation up to 1500 degrees F (816 degrees C). Additionally, it keeps up its good low-temperature endurance.
Applications of SS 321:
- Exhaust stacks and manifolds for aircraft piston engines
- Joints for expansion
- Oxidizers in the heat
- Refinery Machinery
- Equipment for chemical processes at high temperatures
- Storage and equipment for food processing
The following industries employ SS 321:
- Petrochemical
- Air Craft
- Jet engine parts
- Oil & Gas
- Heat Exchangers
- Chemical
- Nuclear Power Plant
- Defense
- Petrochemical
- Breweries
- Mining
- Construction
Corrosion Resistance: Like 304, stainless steel 321 pipes exhibit good all-around corrosion resistance. It was developed for usage in the 1800–1500 °F (416–816 °C) chromium carbide precipitation range, where unstabilized alloys, such as 304, are vulnerable to intergranular assault.
The alloy can be used in pure phosphoric acid at low temperatures, most diluted organic acids at moderate temperatures, up to 10% diluted solutions at high temperatures, and most diluted organic acids.
Stainless steel 321 tubes resist polythionic acid stress corrosion cracking in hydrocarbon service. It can also be used in fluoride- or chloride-free caustic solutions at mild temperatures. Even at low concentrations, SS 321 does not function well in sulfuric acid service or chloride solutions.
Machining: The same hard, stringy chips will be produced by 304 stainless steel and 321 stainless steel. Slow speeds and heavy feeds will reduce this alloy’s tendency to work harder.
Techniques for Welding & Annealing: 321 All typical welding methods, including submerged arc, work well for welding stainless steel. Most typically, AWS E/ER 347 or E/ER 321 are considered suitable weld fillers. The main distinction between this alloy and 304 and 304L stainless steel is the addition of titanium, which eliminates or delays carbide precipitation during welding.
Annealing at air-cooled temperatures of 1800–2000°F (928–1093°C). Maximum ductility will be obtained using this procedure. See the comment on settled anneal under corrosion for the highest level of corrosion resistance. Heat treatment is not used to harden this stainless steel. Cold reduction is the only way to get high attributes.
Techniques for Hot and Cold Work: Forging, upsetting, and other hot work processes call for working temperatures of 2100-2300 degrees F (1149-1260 degrees C). Work with this stainless steel at no less than 1700 degrees Fahrenheit (927 degrees C). To maintain the highest level of corrosion resistance, the material must either be thoroughly annealed or water quenched after working.
Compared to 304 stainless steel, this material requires greater initial stresses, yet despite this, it is a little bit more brittle and ductile and can be spun, drawn, stamped, and blanked.