321 Stainless Steel Property Data

321 Stainless Steel is a titanium stabilised chromium-nickel austenitic stainless steel with good strength and excellent corrosion resistance, as supplied in the annealed condition with a typical brinell hardness of 175. Characterised by high corrosion resistance in general atmospheric corrosive environments it exhibits excellent resistance to most oxidizing agents, general foodstuffs, sterilizing solutions, dyestuffs, most organic chemicals plus a wide variety of inorganic chemicals, also hot petroleum gases, steam combustion gases, nitric acid, and to a lesser extent sulphuric acid. It displays good oxidation resistance at elevated temperatures has excellent resistance to intergranular corrosion and has excellent weldability. 321 Stainless Steel cannot be hardened by thermal treatment, but strength and hardness can be increased substantially by cold working, with subsequent reduction in ductility.
Used extensively for applications where the addition of titanium and its stabilizing effect as a carbide forming element allows it to be welded and/or used within the carbide precipitation range 430oC - 870oC without the risk of intergranular corrosion. These includeStainless Steel Flanges, Aircraft piston engine manifolds and exhaust stacks, Stainless Steel Pipes, Oil and gas equipment, Offshore technology, Seawater desalination plants, Chemical industry, especially when handling chlorides, Flue-gas cleaning, Desalination plants and seawater systems, Pulp and paper industry, Cargo tanks and pipe systems in chemical tankers, Firewalls and blast walls on offshore platforms, Bridges, Stainless Steel Pipe Fittings, Pressure vessels, reactor tanks, and heat exchangers, Rotors, impellers and shafts etc.
Material non magnetic in the annealed condition, but can become mildly magnetic following heavy cold working.
Annealing is required to rectify if necessary.
N.B. Optimum corrosion resistance is achieved in the annealed condition.

Related Specifications
Australia	AS 2837-1986-321
Germany	W.Nr 1.4541 X6CrNiTi18 10
Great Britain	BS970 Part 3 1991 321S31 BS970 - 1955 EN58B/EN58C
Japan	JIS G4303 SuS 321
USA	ASTM A276-98b 321 SAE 30321 AISI 321 UNS S32100

Chemical Composition
	Min. %	Max %
Carbon	0	0.08
Silicon	0	1.00
Manganese	0	2.00
Nickel	9.00	12.00
Chromium	17.00	19.00
Titanium	5 x Carbon	0.80
Phosphorous	0	0.045
Sulphur	0	0.03

Elevated Temperature Properties
321 Stainless Steel displays good oxidation resistance in continuous service up to 930oC, and in intermittent service up to 870oC. It can also be used within the carbide precipitation range 430oC - 870oC without the risk of intergranular corrosion. Mechanical properties are reduced as temperature increases.
Typical Mechanical Properties - Annealed at Elevated Temperatures
Temperature oC			20	430	550	650	760	870
Short - Time Tensile Tests		Tensile Strength Mpa	580	425	365	310	205	140
		Yield Strength Mpa	240	170	150	135	105	70
		Elongation in 50mm %	60	38	35	32	33	40
Creep Tests		Stress for 1% Creep in 10,000 Hours Mpa			115	50	14

Hot Working		Working temperatures of 2100-2300 F (1149-1260 C) are recommended for forging, upsetting and other hot work processes. Do not work this alloy at temperatures below 1700 F ( 927 C). Material must be water quenched or fully annealed after working to reattain maximum corrosion resistance.

Cold Working

Although this material requires higher initial forces than 304 stainless, it is quite tough and ductile and can be readily stamped, blanked, spun and drawn.

Applications

Jet engine parts, furnace heat treated parts, expansion joints, turbo superchargers, oil refiners, exhaust manifolds and high temperature chemical production equipment.

321 Stainless is available in the following forms at Yaang

• Stainless Steel Elbows
• Stainless Steel Angle Bars
• Stainless Steel Bars
• Stainless Steel Pipe Fittings
• Stainless Steel Tubes
• Stainless Steel Flanges (i.e. flanges, slip-ons, blinds, weld-necks, lapjoints, long welding necks, socket welds, elbows, tees, stub-ends, returns, caps, crosses, reducers, and pipe nipples)
• Stainless Steel U Tubes
• Stainless Steel Concentric Reducer
  
• Stainless Steel Pipes

Notes on Carbide Precipitation and the Stabilizing Action of Titanium

Stainless steels during annealing are heated to fairly high temperatures, typically 1050oC - 1100oC to ensure that all chromium carbides present are dissolved and all of the chromium is taken into solution in the austenite. The steel is then quench-annealed as rapidly as possible generally in clean water, but thin sections (pipe etc.) can be air cooled, this being necessary to suppress any re-formation of chromium carbide which would occur if the material was allowed to slow cool in the furnace etc. as with standard annealing procedures.The resultant austenitic structure at room temperature has optimum corrosion resistance containing as it does all of the chromium in solution. If subsequently used in service at room temperature while some slight precipitation of chromium carbide can occur over an extended period this will generally have little affect on corrosion resistance. This situation changes drastically when heat is applied either in service, or during welding, especially when heating through the range 430oC - 850oC, then the carbon and chromium atoms will move (precipitate) coming together to form chromium carbide (Cr23C6), depleting the structure of chromium and its corrosion resistance.
To overcome this problem, two methods have been adopted:
1) Use a low carbon grade - 304L Stainless Steel or 316L Stainless Steel etc.
2) Use a titanium stabilized grade - 321 Stainless Steel etc.
Low carbon grades have insufficient carbon to deplete the chromium content generally throughout the structure, However local depletion within the weld area can still be a problem leading to some intergranular corrosion if later exposed to severe corrosive conditions.

Titanium acts as a stabilizer because the carbon has more affinity to it than it has to the chromium, thus titanium carbide is formed instead and the chromium is unaffected giving the material optimum corrosion resistance.

Source: Yaang Pipe Industry Co., Limited (www.yaang.com)

Next: 321 Stainless Steel Technical Data Sheet By yaang.com
Prev: List of Chemical Elements