As a modified version of SS304, stainless steel 321 (SS321) is a stabilized austenitic stainless steel with a titanium addition of at least 5 times the carbon content. The titanium addition reduces or prevents the sensitization of carbide precipitation during welding and in services at the temperature range of 425-815°C. It also improves the some of the properties at elevated temperatures. SS321 provides outstanding resistance to oxidation and corrosion and has good creep strength. It is used primarily in oil refinery equipment, pressure vessel piping, radiant superheaters, bellews, and high-temperature heat treatment equipment.

1. UNS Designation & International Equivalent

Type	UNS	JIS	EN/DIN	EN/BS	EN/NF	ISO	GB	GOST
321	S32100	SUS321	X6CrNiTi18-10	321S31	X6CrNiTi18-10	15	0Cr18Ni10Ti	08KH18H10T

2. Product Forms and Standards

Product Forms	Material Standards
Plates, Sheets & Strips	ASTM A240
Billets, Bars & Rods	ASTM A276, A314, A479
Forgings(Flanges & Fittings)	ASTM A182, A473.
Wires	ASTM A313, A580.
Seamless and Welded Pipes	ASTM A312, A358, A813, A814.
Wrought Pipe Fittings	ASTM A403

*Especially, Metals-Piping supplies SS321 in the grades of ASTM A312 TP321, ASTM A182 F321, ASTM A403 WP321.

3. Physical Properties of SS321

Density	Electrical Resistivity	Thermal Conductivity	Magnetic Permeability	Specific Heat	Melting Range
g/cm3	µΩ·cm	W/mK	H/m at 200 Oersteds	kJ/kg/K	°C
8.09	72	16.0	≤1.02	0.50	1371-1399

4. Chemical Composition of SS321

The Chemical Composition of SS321, %
Carbon	≤0.08
Manganese	≤2.00
Phosphorus	≤0.045
Sulfur	≤0.030
Silicon	≤0.75
Chromium	17.00-19.00
Nickel	9.00-12.00
Titanium	≤0.70
Nitrogen	≤0.10
Iron	Balance

5. Mechanical Properties of SS321

Tensile Strength,min.	Yield Strength, min.	Elongation	Hardness
ksi(Mpa)	ksi(Mpa)	%
85(586)	35(241)	55	B70

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