SUS321 Stainless Steel: Composition, Properties, and Applications Guide

SUS321 stainless steel is a titanium-stabilized austenitic stainless steel grade under the Japanese JIS standard, equivalent to AISI 321 and EN 1.4541. It is specifically designed to resist intergranular corrosion after welding or exposure to high temperatures (450–900°C), making it an excellent choice for heat-resistant and chemical process equipment.
Compared with SUS304, SUS321 offers improved creep strength and resistance to carbide precipitation, thanks to titanium (Ti) addition. This makes it a reliable option for high-temperature piping systems, exhaust manifolds, and pressure vessels.

 

Is SUS321 equivalent to AISI 321?
Yes. SUS321 (JIS) is equivalent to AISI 321 (ASTM/SAE) and EN 1.4541.

 

Chemical Composition of SUS321 Stainless Steel

Element	Composition (%)
Carbon (C)	≤ 0.08
Silicon (Si)	≤ 1.00
Manganese (Mn)	≤ 2.00
Phosphorus (P)	≤ 0.045
Sulfur (S)	≤ 0.030
Chromium (Cr)	17.00 – 19.00
Nickel (Ni)	9.00 – 12.00
Titanium (Ti)	≥ 5 × C% and ≤ 0.70

Mechanical Properties of SUS321 Stainless Steel

Property	Metric	Imperial
Tensile Strength (min)	515 MPa	74.7 ksi
Yield Strength (min, 0.2% offset)	205 MPa	29.7 ksi
Elongation (min)	40%	40%
Hardness (max)	217 HB	217 HB
Density	7.93 g/cm³	0.286 lb/in³
Melting Range	1400–1425°C	2550–2600°F

 

Is SUS321 stainless steel magnetic?
No, SUS321 is generally non-magnetic in the annealed condition, but slight magnetism may develop after cold working.

 

Typical Applications of SUS321 Stainless Steel

Chemical processing equipment – reactors, heat exchangers, piping

Petrochemical plants – refinery heater tubes, high-temperature ducts

Automotive and aerospace exhaust systems

Boiler and superheater tubing

Food processing machinery (for high-heat sterilization processes)

Expansion joints and bellows

 

What's the maximum service temperature for SUS321?
Continuous service: up to 870°C (1600°F); intermittent service: up to 925°C (1700°F).

 

What is the difference between SUS321 and SUS304?
SUS321 and SUS304 are both austenitic stainless steels, but SUS321 contains titanium, which enhances its resistance to intergranular corrosion, especially after welding or high-temperature exposure.
The titanium in SUS321 prevents chromium carbide precipitation, eliminating the risk of weld decay.

 

If you need stainless steel that withstands high temperatures, high-frequency welding, and intergranular corrosion, SUS321 stainless steel is your ideal choice. Its high mechanical strength, oxidation resistance, and durability make it widely used in industrial thermal environments.
Contact us today to order SUS321 seamless pipe, welded pipe, and plate-all manufactured to ASTM, JIS, and EN standards and backed by comprehensive mill-test certification.Email: sales@gneestainless.com