Leading Supplier of Stainless Steel 321
Specifications of Grade 321 Stainless Steel also equivalent to
SUS321 | SS321 | UNS S32100 | 1.4541
Properties of SUS321 Stainless Steel
Stainless Steel Grade 321 (SUS321) and Stainless Steel Grade 347 (SUS347) are the basic austenitic 18/8 steel (SUS304) stabilised by Titanium (SUS321) or Niobium (SUS347) additions. These grades are used because they are not sensitive to inter-granular corrosion after heating within the carbide precipitation range of 425-850°C.
SS321 (Stainless Steel Type 321) is the grade of choice for applications in the temperature range of up to about 900°C, combining high strength, resistance to scaling and phase stability with resistance to subsequent aqueous corrosion.
SUS321H is a modification of SUS 321 with higher carbon content, to provide improved high-temperature strength.
A limitation with SUS321 is that titanium does not transfer well across a high temperature arc, so is not recommended as a welding consumable. In this case SUS 347 is preferred – the niobium performs the same carbide stabilization task but can be transferred across a welding arc. SS347 is, therefore, the standard consumable for welding SS 321. SS 347 is only occasionally used as parent plate material.
Like other austenitic grades, Grade 321 and Grade 347 Stainless Steel have excellent forming and welding characteristics, are readily brake or roll formed and have outstanding welding characteristics. Post-weld annealing is not required. They also have excellent toughness, even down to cryogenic temperatures. SUS321 does not polish well, so is not recommended for decorative applications.
Grade 304L Stainless Steel (SUS304L) is more readily available in most product forms, and so is generally used in preference to 321 if the requirement is simply for resistance to intergranular corrosion after welding. However, SUS304L has lower hot strength than SUS321 and so is not the best choice if the requirement is resistance to an operating environment over about 500°C.
Chemical Formula of SUS 321 Stainless Steel
Fe | <0.08% C | 17-19% Cr | 9-12% Ni | <2% Mn | <1% Si | 0.3-0.7% Ti | <0.045% P | <0.03% S
These properties are specified for flat rolled product (plate, sheet and coil) in ASTM A240/A240M. Similar but not necessarily identical properties are specified for other products such as pipe and bar in their respective specifications.
Mechanical Properties for SS321
|Grade||Tensile Strength (MPa) min||Yield Strength 0.2% Proof (MPa) min||Elongation (% in 50mm) min||Hardness|
|Rockwell B (HR B) max||Brinell (HB) max|
* SUS 321H also has a requirement for a grain size of ASTM No 7 or coarser.
Physical Properties for SS 321
|Grade||Density (kg/m3)||Elastic Modulus (GPa)||Mean Coefficient of Thermal Expansion (mm/m/°C)||Thermal Conductivity (W/m.K)||Specific Heat 0-100°C (J/kg.K)||Electrical Resistivity (nW.m)|
|0-100°C||0-315°C||0-538°C||at 100°C||at 500°C|
Corrosion Resistance for UNS S32100 Stainless Steel
Equivalent to SUS304 in the annealed condition, and superior if a weldment in these grades has not been post-weld annealed or if the application involves service in the 425-900°C range.
Subject to pitting and crevice corrosion in warm chloride environments, and to stress corrosion cracking above about 60°C. Considered resistant to potable water with up to about 200mg/L chlorides at ambient temperatures, reducing to about 150mg/L at 60°C.
Heat Resistance for SUS 321 Stainless Steel
Good oxidation resistance in intermittent service to 900°C and in continuous service to 925°C. These grades perform well in the 425-900°C range, and particularly where subsequent aqueous corrosive conditions are present.
SUS321H has higher hot strength and is particularly suitable for high-temperature structural applications.
Heat Treatment for SS321 Stainless Steel (1.4541)
Solution Treatment (Annealing)
heat to 950-1120°C and cool rapidly for maximum corrosion resistance.
heat to 870-900°C for 1 hour per 25mm of thickness and air cool. Stabilization is recommended for most severe service conditions (above 425°C) and particularly for material annealed at the upper side of the annealing temperature range.
Heat to 700°C for 1 to 2 hours and air cool.
* These grades cannot be hardened by thermal treatment.
Excellent weldability by all standard fusion methods, both with and without filler metals. AS 1554.6 pre-qualifies welding of SUS321 and SUS347 with Type 347 Stailess Steel rods or electrodes; high silicon version of SUS 347 is also pre-qualified for welding of SUS 321.
Comparison of SUS321 Stainless Steel (UNS S32100)
|Grade||UNS No||Old British||Euronorm||Swedish SS||Japanese JIS|
|SS321||S32100||321S31||58B, 58C||1.4541||X6CrNiTi18-10||2337||SUS 321|
* These comparisons are approximate only. The list is intended as a comparison of functionally similar materials, not as a schedule of contractual equivalents. If exact equivalents are needed original specifications must be consulted.
Possible Alternative Grades to Grade 321 Stainless Steel
|Grade||Why it might be chosen instead of 321|
|SS304L||The requirement is for resistance to intergranular corrosion, not for high temperature strength|
|3CR12||Only mild “high temperature” environment is present… up to about 600°C.|
|SS304H||Only mild “high temperature” environment is present… up to about 800°C.|
|SS310||The temperature of the operating environment is up to about 1100°C – too high for 321 or 321H.|
|The temperature of the operating environment is up to about 1150°C- too high for 321 or 321H.|
Technical Applications in Type 321 Stainless Steel
SUS321 Stainless Steel can be used in the following applications :
- Furnace parts
- Oil burner parts
- Carburising boxes
- Heat Treatment baskets and jigs
- Heat Exchangers
- Welding filler wire and electrodes
Our Sales and Supplier Network in SUS321 / SS321 / 321 Grade Stainless Steel :
With over 15 years of experience and strong global sourcing networking in the market, we are proud to be the SUS 321 Stainless Steel Supplier and Exporter to :
- Australia, Pakistan, Malaysia, Singapore, Taiwan, China, Vietnam, Belgium, Japan, South Korea, Philippines, France, United Kingdom, Indonesia, Thailand, Hong Kong, China, Sweden, United States, Dubai, Finland, Brunei, Germany.
Besides, we have the full range of Stainless Steel sheets, Stainless Steel Round Bar, Stainless Steel Rods, Stainless Steel Plate which consists of
– 300 Series Stainless Steel : SUS304, SUS304L, SUS309, SUS310, SUS316Ti, SUS317, SUS321, SUS347
– 400 Series Stainless Steel : SUS403, SUS410, SUS420, SUS431, SUS440C, SUS630, SUS904L
– Nitronic 30, Nitronic 50, Nitronic 60
– Super Duplex S32750, S32760