Grade 321/321H Stainless Steel Plate
Stainless Metal Grades to Fit Your Needs
Grade 321 stainless steel plate is a standard 18/8 chromium-nickel alloy reinforced by titanium and niobium. The addition of titanium stabilizes this alloy and removes its susceptibility to intergranular corrosion while mitigating carbide precipitation during welding. At elevated temperatures, it resists oxidation and has higher creep and rupture properties than 304/304L stainless steel.
Grade 321H stainless steel plate contains more carbon (between 0.04% to 0.1%) than regular 321 (≥ 0.08%), which enhances its high-temperature performance, including increasing its resistance to cracking or warping due to shifts in temperature.
0.188-3.5″
Thickness
96-240″/480″
Length
96″/120″
Width
Why Engineers Choose 321/321H Plate
For High-Temperature Service (up to 1,650°F):
Unlike 304 stainless steel, Grade 321 maintains structural integrity and corrosion resistance through repeated thermal cycling, making it the preferred choice for furnace parts, heat exchangers, and exhaust manifolds.
For Welded Assemblies:
Titanium stabilization eliminates carbide precipitation during welding, maintaining full corrosion resistance without costly post-weld heat treatment – critical for field-fabricated vessels and piping systems.
For Long-Term Reliability:
In continuous service at 1,000-1,600°F, Grade 321H delivers superior creep resistance and extended service life compared to non-stabilized austenitic grades, reducing maintenance intervals and replacement costs.
Design Limitations to Consider:
- Requires careful selection for acidic service conditions.
- Not suitable as welding wire/consumable
- Cannot achieve mirror polish finishes
Technical Specifications & Properties
Chemical Composition
Grade 321 Stainless Steel:
| Chromium (Cr) | 17.0-19.0% |
| Nickel (Ni) | 9.0-12.0% |
| Titanium (Ti) | 5 x (C+N) min, 0.70% max |
| Manganese (Mn) | ≤2.0% |
| Silicon (Si) | ≤0.75% |
| Phosphorus (P) | ≤0.045% |
| Sulfur (S) | ≤0.030% |
| Carbon (C) | ≤0.08% |
| Iron (Fe) | Balance |
Grade 321H Stainless Steel:
| Chromium (Cr) | 17.0-19.0% |
| Nickel (Ni) | 9.0-12.0% |
| Titanium (Ti) | 4 x (C+N) min, 0.70% max |
| Carbon (C) | 0.04-0.10% |
Other elements similar to Grade 321
Corrosion Resistance
Grade 321/321H offers excellent resistance to:
- Intergranular Corrosion: Titanium stabilization prevents chromium carbide precipitation at grain boundaries
- Oxidation: Superior resistance at temperatures up to 870°C in continuous service
- Scaling: Maintains surface integrity at high temperatures
- General Corrosion: Good resistance in mild atmospheric conditions and fresh water
- Stress Corrosion Cracking: Moderate resistance in chloride environments
Note: While resistant to many environments, 321 has limited resistance to reducing acids and chloride-containing solutions at elevated temperatures.
High-Temperature Performance
- Maximum continuous service temperature: 870°C (1600°F)
- Maximum intermittent service temperature: 925°C (1700°F)
- Grade 321H offers superior creep resistance above 600°C (1110°F)
- Maintains structural integrity and strength at elevated temperatures better than 304/304L
Fabrication & Welding Characteristics
Forming:
- Can be cold worked using standard techniques
- Annealing temperature: 1010-1120°C (1850-2050°F)
- Work hardening rate similar to 304 stainless steel
- Excellent formability in annealed condition
Heat Treatment
- Solution annealing: Heat to 1010-1120°C (1850-2050°F), rapid cooling
- Cannot be hardened by heat treatment
- Stress relieving (if required): 400-420°C (750-790°F) for 1-2 hours
Welding:
- No post-weld heat treatment required due to titanium stabilization
- Suitable for all standard welding methods (TIG, MIG, resistance welding)
- Use 347 filler metal for optimal results
- Not recommended as welding consumable due to titanium content affecting arc stability
Surface Finishes Available
- No. 1 (Hot Rolled, Annealed & Pickled)
- 2B (Cold Rolled, Annealed & Pickled)
- 2D (Cold Rolled, Annealed & Pickled, Dull Finish)
Note: Not recommended for polished finishes due to titanium inclusions
Grade 321 and 321H Stainless Steel Plate Processing Services
In conjunction with our extensive material stock, Sabre Alloys offers various steel processing services to meet our customers’ material requirements better. Our value-added 321 and 321H stainless steel services allow us to meet exact specifications with short turn-around times.
Sabre Alloys offer the following value-added steel processing services:
Grade 321 and 321H Stainless Steel Plate Applications
Because of its ability to withstand high temperatures and superior resistance to various forms of corrosion, Grade 321 and 321H stainless steel plate are used in many different applications. Because of its outstanding heat resistance compared to other stainless steels, both grades are often used in pressure vessels, boilers, exhaust systems, and heat exchangers.
Sabre Alloys streamlines our customers’ ASTM 321 and 321H stainless steel supply chain in numerous industries by reducing the lead time associated with stainless steel acquisition and processing. View All Industries to see a comprehensive list of our applications.
industries served
- Water
- Food processing
- Environmental
- Architecture
- Appliances
- Pharmaceutical
Contact Sabre Alloys
As a full-service stainless steel distributor, Sabre Alloys prides itself on getting you the steel you need, exactly how and when you need it. Let us help you save time and money with our high-quality ASTM A240 Grade 321 and 321H stainless steel plate and processing services.
For more information about our Grade 321 and 321H plate products, please Contact Our Team at Sabre Alloys today.
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Whether you need material for a new product application or you want to replace your existing supply, let our talented staff at Sabre Alloys be your partners for sourcing exotic, high-quality stainless steel. Request a quote today.
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Frequently Asked Questions
What is the difference between 321 and 304 stainless steel at high temperatures?
At elevated temperatures, 321 significantly outperforms 304 stainless steel. The titanium stabilization in 321 prevents carbide precipitation during welding and high-temperature exposure (425-815°C), maintaining corrosion resistance where 304 would become susceptible to intergranular corrosion. Additionally, 321 exhibits superior creep resistance and maintains higher strength values above 600°C, making it the preferred choice for continuous service up to 870°C compared to 304’s practical limit of about 790°C.
Does 321 require post-weld heat treatment?
No, Grade 321 does not require post-weld heat treatment (PWHT). The titanium content acts as a stabilizing element that prevents chromium carbide precipitation during welding, maintaining the material’s corrosion resistance in the heat-affected zone. This is one of the primary advantages of 321 over non-stabilized grades like 304, making it ideal for fabricated components that cannot be solution annealed after welding.
Can 321 stainless steel plate be used in acidic environments?
Grade 321 has limited resistance to acidic environments, particularly reducing acids like hydrochloric and sulfuric acid. It performs well in mild organic acids and oxidizing acids like nitric acid at moderate concentrations and temperatures. For applications involving strong acids or elevated temperatures with acidic exposure, consider more resistant grades like 316L or super duplex stainless steels. Always consult corrosion data for your specific acid concentration and temperature conditions.
Is 321 stainless steel plate available in hot rolled and cold rolled finishes?
Yes, Grade 321 stainless steel plate is available in both hot rolled and cold rolled conditions. Hot rolled plate (Condition A, No. 1 finish) is typically available in thicknesses from 3/16″ and above, featuring a scaled surface that’s subsequently pickled. Cold rolled plate (2B or 2D finish) is generally available in thinner gauges up to about 1/2″ and provides a smoother, more uniform surface finish with tighter thickness tolerances.
What ASTM specifications apply to 321 stainless steel plate?
Grade 321 and 321H stainless steel plates are primarily covered under ASTM A240/A240M specification, which defines the chemical composition, mechanical properties, and general requirements. The standard thickness tolerances follow ASTM A480/A480M for general requirements. Plates typically meet dual certification requirements and may also conform to ASME SA-240 for pressure vessel applications. Standard mill tolerances for thickness are typically +/- 0.01″ or 3%, whichever is greater.
Similar Steel Plate Products
Sabre Alloys aims to be your solution center for exotic, high-quality stainless steel plate. We offer hard-to-find metal grades and we cater to a wide range of industries.