Stainless Steel 321 (UNS S32100) for Applications Using Continuous and Intermittent Service Temperatures

The 321 stainless steel is mainly used in applications that involve continuous and intermittent service temperatures within the carbide precipitation range of 800°-1500°F.

Type 321 is similar to type 304 stainless but with titanium addition of 5 times the carbon content. This titanium addition reduces or prevents carbide precipitation during welding and in the 800°-1500°F service conditions. For providing 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.

Stainless Steel 321 Chemical Composition, %

The chemical composition of stainless steel 321 is:

	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	Balance

Forms of 321 Stainless Steel

321 Stainless Steel is available in the following forms at Yaang Pipe Industry Co., Limited:

• Plate
• 321 Stainless Steel Seamless and Welded Pipe Bend
• Bar
• 321 Stainless Steel Pipe & 321 Stainless Steel U Tube .
• Fittings (i.e., flanges, slip-ons, blinds, weld-necks, lap joints, long welding necks, socket welds, elbows, tees, stub-ends, returns, caps, crosses, reducers, and pipe nipples)
• Weld Wire.

Features of Stainless Steel 321

The features of stainless steel 321 are:

• Oxidation resistant to 1600°F.
• Stabilized against weld heat affected zone (HAZ) intergranular corrosion.
• Resists polythionic acid stress corrosion cracking.

Mechanical Properties (Average Elevated Temperature Tensile Properties)

The mechanical properties of stainless steel 321 are:

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 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 normally considered to have comparable weldability to 304 and 304L stainless with the main difference being the titanium addition which reduces or prevents carbide precipitation during welding.

Applications

The applications of stainless steel 321 are:

• Expansion joints
• Thermal oxidizers
• Refinery equipment
• Aircraft piston engine manifolds and exhaust stacks
• High temperature chemical process equipment.

This information has been sourced, reviewed and adapted from materials provided by Yaang Pipe Industry Co., Limited.

For more information on this source, please visit Yaang Pipe Industry Co., Limited.

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