Stainless Steel, Austenitic
321 Stainless Steel (S32100) Coil
A titanium-stabilised chromium-nickel austenitic stainless steel with very good corrosion resistance.
Stainless steel 321 is the stabilized version of stainless steel 304. The 18/8 blend of chromium and nickel is tempered with titanium to give type 321 protection from intergranular corrosion that can occur after heat treatment. It is protected from temperatures ranging from 800 to 1500° F. The metal displays high strength and resistance to various forms of corrosions, including that from aqueous environments.
Type 321 finds application in heavy welding components, along with dynamic environments that are subject to changes.
However, the addition of titanium limits the application of 321 in terms of working. The metal is not recommended for certain welding techniques as it is not consumable. Beyond this, stainless steel 321 has excellent forming characteristics, does not require annealing after being welded, and displays toughness in a range of temperatures.
The metal shows strength even when exposed to cryogenic temperatures. Additionally, it is often chosen over Type 304 for its increased resistance to creep and rupture. Both metals may be susceptible to stress corrosion cracking.
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Range
| Bar Products | Imperial Sizes | Metric Sizes |
| Round Bar Bright Drawn H9 | 1⁄8" - 7⁄8" | 4mm - 25mm |
| Round Bar Smooth Turned H9/H10 | 1" - 3" | 30mm |
| Round Bar Peeled K12/K16 | 3 1⁄4" - 6" | - |
| Sheet Size | Finish | Thicknesses |
| 2500 x 1250 | 2B | 1.5mm - 3.0mm |
PLEASE NOTE
If you do not see what you are looking for, please contact your local service centre with your specific requirements.
Related Specifications
Here is a comparison table for 321 stainless steel grades (chemical equivalents and common international standards):
- S32100
- X6CrTi18-10
- 1.4541
- SUS321
- 0Cr18Ni9Ti
- 321
Properties
Chemical Composition
| Chemical Element | % Present |
| Chromium (Cr) | 17.00 - 19.00 |
| Nickel (Ni) | 9.00 - 12.00 |
| Molybdenum (Mo) | 0.00 - 0.75 |
| Copper (Cu) | 0.00 - 0.75 |
| Titanium (Ti) | 0.00 - 0.70 |
| Carbon (C) | 0.00 - 0.08 |
| Manganese (Mn) | 0.00 - 2.00 |
| Silicon (Si) | 0.25 - 1.00 |
| Phosphorous (P) | 0.00 - 0.04 |
| Sulphur (S) | 0.00 - 0.03 |
| Nitrogen (N) | 0.00 - 0.10 |
Mechanical Properties
321 Stainless Steel Bar
| Mechanical Property | Value |
| 0.2% Proof Stress | 205 N/mm2 |
| Elongation A50 mm | 40 % |
| Hardness Brinell | 217 max HB |
321 Stainless Steel Sheet
ASTM A240
| Mechanical Property | Value |
| Proof Stress | 205 Min MPa |
| Tensile Strength | 515 Min MPa |
| Elongation A50 mm | 35 Min % |
General Physical Properties
| Physical Property | Value |
| Density | 8.09 g/cm³ |
| Melting Point | 1400-1427 °C |
| Modulus of Elasticity | 193 GPa |
| Electrical Resistivity | 0.074 x 10-6 Ω .m |
| Thermal Conductivity | 16.1 W/m.K |
Applications of 321 Stainless Steel
321 stainless steel is a titanium-stabilized austenitic stainless steel with excellent resistance to intergranular corrosion and good high-temperature strength. Its stability in welded and heat-affected areas makes it suitable for a wide range of industrial and high-temperature applications.
1. High-Temperature Industrial Applications
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Furnace parts, heat exchangers, and chimneys
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Boiler components, hot gas ducts, and superheaters
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Components exposed to temperatures up to ~900°C (1650°F)
2. Chemical and Petrochemical Industry
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Tanks, piping, and valves handling mildly corrosive chemicals
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Equipment operating under oxidizing and high-temperature conditions
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Components requiring welded assemblies with intergranular corrosion resistance
3. Aerospace and Automotive Applications
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Exhaust systems and turbocharger components
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High-temperature automotive components exposed to oxidizing environments
4. Food and Pharmaceutical Processing
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Equipment requiring resistance to corrosion during cleaning and sterilization
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Processing vessels exposed to hot and corrosive environments
5. Architectural and Structural Applications
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Structures exposed to moderately high temperatures and polluted atmospheres
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Cladding, panels, and piping in industrial buildings
6. Comparison to Other Austenitic Grades
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More heat-resistant than 304/304L
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Offers better weldability and resistance to intergranular corrosion than standard 304 in high-temperature applications
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Titanium addition prevents sensitization in welded areas
Summary
321 stainless steel is widely used in high-temperature, chemical, aerospace, and industrial applications due to its excellent intergranular corrosion resistance and thermal stability. Its titanium stabilization makes it particularly suitable for welded components that require durability under heat and corrosive conditions.
Characteristics of 321 Stainless Steel
321 stainless steel is a titanium-stabilized austenitic stainless steel designed to resist intergranular corrosion and maintain high strength at elevated temperatures. The addition of titanium stabilizes the material, preventing chromium carbide precipitation during welding or high-temperature service.
1. Corrosion Resistance
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Excellent resistance to oxidation and corrosion in moderate to high-temperature environments.
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Titanium addition prevents sensitization, maintaining corrosion resistance in welded areas.
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Suitable for environments with oxidizing chemicals and atmospheric exposure.
2. High-Temperature Performance
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Retains mechanical strength at temperatures up to ~900°C (1650°F).
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Suitable for continuous high-temperature service in oxidizing atmospheres.
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Exhibits good creep and stress-rupture properties.
3. Mechanical Properties
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Excellent tensile strength, ductility, and toughness, even at elevated temperatures.
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Work-hardens moderately during cold forming, allowing increased strength where required.
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Maintains dimensional stability in welded assemblies.
4. Fabrication and Formability
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Can be cold-worked (rolling, bending, deep drawing) and hot-worked (forging, extrusion, hot rolling) efficiently.
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Titanium stabilization ensures welded structures maintain corrosion resistance without post-weld heat treatment.
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Low risk of intergranular corrosion in welded or heat-affected zones.
5. Weldability
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Excellent weldability with TIG, MIG, and resistance welding.
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Titanium prevents carbide formation during welding, eliminating the need for post-weld solution annealing in most cases.
6. Applications Leveraging Characteristics
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High-temperature furnace components, heat exchangers, and boilers
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Chemical processing equipment and piping
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Aerospace and automotive exhaust systems
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Food and pharmaceutical processing equipment
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Architectural structures exposed to heat and industrial atmospheres
Summary
321 stainless steel is distinguished by excellent corrosion resistance, high-temperature strength, titanium stabilization, and good weldability. Its properties make it ideal for industrial, chemical, aerospace, and high-temperature applications, particularly where welded assemblies require durability and resistance to intergranular corrosion.
Additional Information
Weldability
Weldability of 321 Stainless Steel
321 stainless steel is a titanium-stabilized austenitic stainless steel with excellent weldability, thanks to its low carbon content and titanium addition. The titanium prevents chromium carbide precipitation, reducing the risk of intergranular corrosion in welded areas.
1. Suitable Welding Processes
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TIG (GTAW): Ideal for precise and thin-section welds
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MIG (GMAW): Efficient for thicker sections and industrial applications
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SMAW (Shielded Metal Arc Welding): Suitable for field welding and maintenance
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Resistance Welding: Spot and seam welding for sheet metal applications
2. Low Carbon and Titanium Benefits
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Titanium stabilizes the steel, preventing chromium carbide formation in the heat-affected zone.
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Eliminates the need for post-weld solution annealing in most cases.
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Ensures corrosion resistance is maintained in welded and heat-affected areas.
3. Filler Material Recommendations
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Use matching titanium-stabilized fillers, such as ER321, for maintaining corrosion resistance and mechanical properties.
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For dissimilar welds with austenitic stainless steel, ensure compatible filler material is selected to prevent sensitization.
4. Heat Input and Distortion Control
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Austenitic stainless steels have high thermal expansion, which can lead to distortion.
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Moderate heat input and proper sequencing minimize warping.
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Intermittent tack welding can help maintain dimensional accuracy.
5. Applications Leveraging Weldability
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Chemical and petrochemical equipment
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High-temperature furnace components
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Marine and coastal equipment
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Aerospace and automotive exhaust systems
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Food and pharmaceutical processing equipment
Summary
321 stainless steel provides excellent weldability due to titanium stabilization and low carbon content. Welded joints maintain high corrosion resistance and structural integrity, making 321 ideal for industrial, chemical, high-temperature, marine, and food-processing applications.
Fabrication
Fabrication of 321 Stainless Steel
321 stainless steel is a titanium-stabilized austenitic stainless steel with excellent corrosion resistance and high-temperature stability. Its low carbon content and titanium addition allow for versatile fabrication using conventional metalworking processes, while maintaining mechanical properties and corrosion resistance.
1. Forming
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Cold Forming:
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Suitable for bending, rolling, drawing, and stamping
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Work-hardens moderately; intermediate solution annealing may be required for extensive deformation
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Hot Forming:
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Recommended for complex or thick sections at 1010–1175°C (1850–2150°F)
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Ensures uniform mechanical properties and reduces work-hardening
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2. Cutting and Shearing
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Can be cut using laser, waterjet, plasma, or mechanical methods.
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Sharp tools and correct feeds minimize surface work hardening.
3. Machining
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Moderate difficulty due to toughness and work-hardening tendency
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Carbide tools preferred for high-speed operations
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Use coolants or lubricants to reduce heat and improve surface finish
4. Welding
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Excellent weldability with TIG, MIG, SMAW, or resistance welding
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Titanium prevents intergranular corrosion in welded areas
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Filler material: ER321 recommended for matching composition and corrosion resistance
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Post-weld heat treatment is generally not required
5. Cold and Hot Working
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Cold working increases strength through work hardening; solution annealing may be needed to restore ductility
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Hot working produces uniform properties and is recommended for thick or complex components
6. Surface Finishing
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Available in 2B (mill finish), BA (bright annealed), and polished surfaces
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Cold working may require additional polishing or pickling for aesthetic or corrosion-sensitive applications
7. Applications Leveraging Fabrication
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Chemical and petrochemical vessels and piping
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High-temperature furnace and boiler components
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Aerospace and automotive exhaust systems
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Food and pharmaceutical processing equipment
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Architectural structures exposed to heat or industrial atmospheres
Summary
321 stainless steel is highly versatile and easy to fabricate, offering excellent cold and hot formability, machining, and welding properties. Titanium stabilization ensures corrosion resistance is maintained throughout fabrication, making it ideal for industrial, chemical, aerospace, and high-temperature applications.
Hot Working
Hot Working of 321 Stainless Steel
321 stainless steel is a titanium-stabilized austenitic stainless steel with excellent hot workability, making it suitable for forging, rolling, extrusion, and forming at elevated temperatures. Hot working reduces work hardening and ensures uniform mechanical properties while preserving corrosion resistance.
1. Recommended Hot Working Temperature
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Typical range: 1010–1175°C (1850–2150°F)
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Exceeding this range may cause grain growth, reducing toughness.
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Working below this range increases flow stress, raising the risk of cracking.
2. Suitable Hot Working Processes
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Hot Rolling: Sheets, plates, and structural components
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Hot Forging: High-strength or complex-shaped parts
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Hot Extrusion: Rods, tubes, and profiles
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Hot Pressing/Forming: Thick or large components difficult to cold-work
3. Advantages of Hot Working
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Reduces work hardening compared to cold working
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Enhances ductility and toughness
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Produces uniform grain structure and mechanical properties
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Allows fabrication of large or complex components
4. Post-Hot Working Treatments
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Solution annealing may be applied to relieve residual stresses and restore ductility
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Pickling or passivation enhances surface corrosion resistance after hot working
5. Applications Leveraging Hot Working
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Industrial machinery components
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High-temperature chemical process equipment
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Furnace and boiler components
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Structural parts requiring elevated-temperature shaping
Summary
321 stainless steel demonstrates excellent hot workability, allowing it to be forged, rolled, or formed at 1010–1175°C. Hot working improves ductility, reduces work hardening, and ensures uniform mechanical properties while preserving corrosion resistance, making it ideal for industrial, chemical, high-temperature, and structural applications.
Heat Resistance
Heat Resistance of 321 Stainless Steel
321 stainless steel is a titanium-stabilized austenitic stainless steel designed for high-temperature applications. The addition of titanium prevents chromium carbide precipitation, allowing the steel to maintain corrosion resistance and mechanical strength at elevated temperatures.
1. Continuous Service Temperature
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Suitable for continuous service in oxidizing atmospheres up to ~870°C (1600°F)
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Maintains mechanical properties and corrosion resistance in this range
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Prolonged exposure above 870°C may cause slight scaling and reduction in toughness
2. Intermittent Exposure
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Can tolerate intermittent heating up to ~925°C (1700°F) without significant surface degradation
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Suitable for parts exposed to occasional thermal cycles
3. Oxidation Resistance
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Forms a protective chromium oxide layer in oxidizing atmospheres
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Maintains corrosion resistance under moderate high-temperature conditions
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Not recommended for strongly oxidizing or sulfidizing environments at very high temperatures
4. Thermal Effects on Mechanical Properties
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Retains tensile strength and ductility at moderate high temperatures
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Cold-worked areas may lose some work-hardening benefits after prolonged heat exposure
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Grain growth may occur if exposed to excessive heat without solution annealing
5. Applications Related to Heat Resistance
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Furnace and boiler components
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Heat exchangers, hot gas ducts, and superheaters
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Chemical and petrochemical high-temperature equipment
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Aerospace and automotive exhaust systems
6. Comparison to Other Austenitic Grades
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Heat resistance is slightly lower than 347 stainless steel but superior to 304 and 304L
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Preferred when weldability and corrosion resistance are more critical than extreme high-temperature strength
Summary
321 stainless steel provides excellent high-temperature performance, with continuous service up to ~870°C and intermittent exposure up to ~925°C. Titanium stabilization prevents sensitization, maintaining corrosion resistance and mechanical properties in welded and high-temperature applications, making it ideal for industrial, chemical, and aerospace environments.
Machinability
Machinability of 321 Stainless Steel
321 stainless steel is a titanium-stabilized austenitic stainless steel that exhibits moderate machinability. Its toughness, work-hardening tendency, and low thermal conductivity require special attention to tooling, cutting parameters, and lubrication during machining to achieve high-quality surfaces and efficient production.
1. Work-Hardening Behavior
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321 stainless steel work-hardens quickly during cutting.
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Hardened surfaces increase cutting forces and accelerate tool wear.
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Continuous, smooth cutting is recommended to minimize localized work hardening.
2. Tooling Recommendations
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Carbide tools are preferred for high-speed or heavy-duty machining.
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High-speed steel (HSS) tools can be used at lower speeds for light to medium operations.
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Tools with positive rake angles reduce cutting forces and improve surface finish.
3. Cutting Speeds and Feeds
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Slower cutting speeds than carbon steels are recommended.
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Moderate to heavy feeds ensure continuous chip flow and prevent local work hardening.
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Avoid dwelling or stopping on the workpiece to prevent hard spots.
4. Cooling and Lubrication
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Low thermal conductivity causes heat buildup at the cutting zone.
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Use flood coolant or cutting fluids to reduce heat, extend tool life, and improve surface finish.
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High-pressure lubrication helps evacuate chips efficiently.
5. Chip Formation
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Chips are tough, stringy, and difficult to manage.
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Use chip breakers or special inserts to control chip flow during machining.
6. Surface Finish
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Achievable with sharp tools, proper feeds, and adequate cooling.
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Work-hardened areas may require finishing passes to achieve desired surface quality.
Summary
321 stainless steel has moderate machinability and requires careful tool selection, cutting parameters, and lubrication. When properly managed, high-quality surfaces and dimensional accuracy are achievable, making it suitable for chemical, aerospace, automotive, and high-temperature industrial applications.
Corrosion Resistance
Corrosion Resistance of 321 Stainless Steel
321 stainless steel is a titanium-stabilized austenitic stainless steel with excellent resistance to intergranular corrosion and good general corrosion resistance. The addition of titanium prevents chromium carbide precipitation, maintaining corrosion resistance in welded and high-temperature environments.
1. General Corrosion Resistance
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Resistant to oxidation and corrosion in atmospheric and mildly corrosive environments.
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Suitable for industrial, chemical, and food-processing applications.
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Maintains corrosion resistance even after welding or thermal exposure due to titanium stabilization.
2. Intergranular Corrosion Resistance
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Titanium forms stable carbides, preventing chromium carbide formation along grain boundaries.
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Reduces the risk of sensitization during welding or high-temperature service.
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Ideal for welded assemblies without requiring post-weld heat treatment.
3. Chloride and Pitting Resistance
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Provides moderate resistance to chloride-induced pitting compared with 304 stainless steel.
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Less resistant than 316 or 317 grades but sufficient for most industrial and chemical applications.
4. High-Temperature Corrosion
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Resistant to oxidation and scaling at elevated temperatures (continuous service up to ~870°C, intermittent up to ~925°C).
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Performs well in oxidizing atmospheres and moderate chemical environments.
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Not recommended for strongly oxidizing or sulfidizing environments at very high temperatures.
5. Applications Leveraging Corrosion Resistance
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Furnace components, boilers, and heat exchangers
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Chemical and petrochemical equipment
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Aerospace and automotive exhaust systems
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Food and pharmaceutical processing equipment
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Welded industrial structures exposed to heat and atmospheric corrosion
Summary
321 stainless steel offers excellent general and intergranular corrosion resistance, especially in welded or high-temperature applications. Titanium stabilization ensures durability in chemical, industrial, aerospace, and high-temperature environments, making it a reliable choice where corrosion resistance is critical.
Heat Treatment
Heat Treatment of 321 Stainless Steel
321 stainless steel is a titanium-stabilized austenitic stainless steel, which is not hardened by heat treatment. Heat treatment is primarily used to relieve stresses, restore ductility, and maintain corrosion resistance, rather than to increase hardness.
1. Solution Annealing
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Purpose:
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Restore ductility after cold working or forming
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Relieve residual stresses
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Dissolve any undesired chromium carbides that may form in improper heating
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Temperature Range: 1010–1120°C (1850–2050°F)
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Cooling: Rapid air or water quench to maintain fully austenitic structure
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Effect:
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Returns mechanical properties to the annealed condition
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Preserves corrosion resistance due to titanium stabilization
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2. Stress Relief
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Purpose: Reduce residual stresses from forming, bending, or welding
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Temperature Range: 450–650°C (840–1200°F)
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Effect: Minimizes distortion and reduces risk of stress corrosion cracking without significantly altering mechanical properties
3. Cold-Worked Condition Considerations
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Cold working increases strength but decreases ductility
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Intermediate solution annealing may be applied to restore formability for further fabrication steps
4. Post-Weld Heat Treatment
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Generally not required due to titanium stabilization and low carbon content
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Stress relief annealing may be applied for dimension-sensitive or high-temperature welded assemblies
5. Limitations
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Heat treatment does not significantly increase hardness
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Prolonged exposure above ~500°C may reduce cold work strengthening effects slightly
Summary
Heat treatment of 321 stainless steel is mainly for stress relief, ductility restoration, and maintaining corrosion resistance. Solution annealing and stress relief ensure optimal mechanical and chemical performance, making 321 ideal for welded, cold-worked, and high-temperature applications.
Cold Working
Cold Working of 321 Stainless Steel
321 stainless steel is a titanium-stabilized austenitic stainless steel that exhibits excellent cold-working properties. Cold working increases strength and hardness through work hardening while maintaining good corrosion resistance and ductility.
1. Work-Hardening Behavior
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321 stainless steel work-hardens moderately during cold deformation.
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Strength and hardness increase, while ductility decreases as deformation progresses.
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Excessive cold working may require solution annealing to restore formability.
2. Common Cold Working Processes
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Rolling: Sheets, strips, and plates
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Drawing: Tubes, rods, and wires
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Bending and Forming: Structural components, brackets, and clips
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Stamping and Deep Drawing: Industrial and food-processing parts
3. Mechanical Properties Control
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Cold working allows adjustment of tensile strength, yield strength, and hardness.
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Extensive cold work may require solution annealing to restore ductility for further fabrication.
4. Effect on Corrosion Resistance
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Titanium stabilization prevents chromium carbide precipitation, maintaining corrosion resistance after cold work.
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Resistant to intergranular corrosion in welded or heavily worked areas.
5. Post-Forming Considerations
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Solution annealing can relieve stresses and restore ductility if multiple cold-working steps are planned.
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Cold working may slightly induce magnetism due to minor martensitic transformation, typically negligible.
6. Applications Leveraging Cold Work
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Springs, clips, and fasteners
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Structural components requiring higher strength
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Tubes, rods, and wires for chemical and food-processing equipment
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Formed components requiring corrosion resistance and strength
Summary
321 stainless steel exhibits excellent cold-working characteristics, allowing increased strength through work hardening while preserving corrosion resistance. Proper management of deformation and intermediate annealing ensures high-quality, durable components for industrial, chemical, food-processing, marine, and structural applications.
