321 Stainless Steel Overview
Stainless Steel 321 is a heat resistant, titanium stabilized, austenitic alloy that’s commonly used for service in the 1000°-1600°F temperature range. 321 stainless steel is primarily used in applications that involve continuous and intermittent service temperatures within the carbide precipitation range of 800°-1500°F. Type 321 stainless steel is similar to type 304 stainless steel but with a titanium addition of at least five times the carbon content. This titanium addition reduces or prevents carbide precipitation during welding and in the 800°-1500°F service conditions. In order to provide optimum resistance to intergranular corrosion and to polythionic acid stress corrosion cracking in service temperatures at 1500°-1650°F an air cool may be used.
What are the characteristics of 321 Stainless Steel?
Oxidation resistant to 1600°F
Stabilized against weld heat affected zone (HAZ) intergranular corrosion
Resists polythionic acid stress corrosion cracking
Stainless Steel 321 Chemical Composition, %
Cr
Ni
Mo
Cu
Ti
C
MIN
17.0
9.0
–
–
5x(C+N)
–
MAX
19.0
12.0
0.75
0.75
0.70
0.08
Mn
Si
P
S
N
Fe
MIN
–
0.25
–
–
–
–
MAX
2.0
1.0
0.04
0.03
0.1
Bal
What applications might 321 Stainless Steel be used?
Aircraft piston engine manifolds and exhaust stacks
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
Stainless Steel Flanges
Mechanical Properties Average Elevated Temperature Tensile Properties
Temperature, °F
Ultimate Tensile Strength, ksi
.2% Yield Strength, ksi
68
84
38
400
62
20.5
600
62
18
800
62
17
1000
59.5
16.5
1200
45.5
16
1400
27.5
14
Welding Stainless Steel 321
321 Stainless Steel is readily welded by all common methods including submerged arc. Appropriate weld fillers are most often specified as AWS E/ER 347 or E/ER 321.
This alloy is generally considered to have comparable weldability to 304 and 304L stainless steel with the main difference being the titanium addition which reduces or prevents carbide precipitation during welding.
321 Stainless is available in the following forms at wilsonpipeline
Stainless Steel Elbows
Stainless Steel Tees
Stainless Steel Bars
Stainless Steel Pipes
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 Pipe Fittings
Source: wilsonpipeline Pipe Industry Co., Limited (www.wilsonpipeline.com)
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