AISI 321H Stainless Steel Plate | 321H China steel mill-Direct Supply
What is AISI 321H Stainless Steel?
As a professional China steel mill-Direct Supply and stainless steel plate supplier, SHH STEEL is pleased to present AISI 321H Stainless Steel Plate.
AISI 321H (UNS S32109) is the high-carbon variant of the titanium-stabilized austenitic stainless steel 321. It contains approximately 17–19% chromium and 9–12% nickel, with carbon intentionally controlled in the range of 0.04–0.10% and titanium added for stabilization. The higher carbon content significantly improves high-temperature strength and creep resistance compared with standard 321, while the titanium stabilization maintains excellent resistance to intergranular corrosion after welding or exposure to the sensitization temperature range.
In addition to the controlled carbon content, AISI 321H is typically produced with a controlled grain size (ASTM No. 6 or coarser) to further enhance long-term creep performance. The grade is particularly suitable for long-term elevated-temperature service under load, such as heat exchangers, furnace components, superheater parts, expansion joints and chemical process equipment operating in the 500–900°C range.
SHH STEEL supplies AISI 321H as true China steel mill-Direct Supply, sourcing directly from major Chinese stainless steel mills. This model delivers competitive mill pricing, consistent quality, complete heat traceability and reliable delivery. SHH STEEL offers AISI 321H in plate and sheet form across a practical range of thicknesses and surface finishes optimized for high-temperature service.
AISI 321H is frequently compared with a240 321, a240 304, a240 304l, a240 347, a240 316ti and a240 310h when selecting materials for elevated-temperature applications. SHH STEEL provides technical support to help customers choose the most appropriate grade.
Material Specification
| Specification Element | Requirement | SHH STEEL Compliance |
|---|---|---|
| Grade | AISI 321H / UNS S32109 | Confirmed |
| Related Standards | ASTM A240, ASME SA240, related high-temperature specs | Available |
| Product Form | Plate, Sheet | Available |
| Delivery Condition | Solution Annealed | Standard |
| Thickness Range | 1 mm – 80 mm (thicker available on request) | Custom sizes supported |
| Width | Up to 2000–3000 mm | Available |
| Length | Up to 12000 mm or cut-to-length | Available |
| Surface Finish | No.1, 2B, and others on request | Available |
| Certification | EN 10204 3.1 / Mill Test Certificate | Available |
SHH STEEL can supply AISI 321H dual-certified to ASTM A240 / ASME SA240 when required by the project.
Chemical Composition
Typical Chemical Composition of AISI 321H (UNS S32109):
| Element | Content (%) |
|---|---|
| Carbon (C) | 0.04 – 0.10 |
| 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) | 4 × (C + N) min – 0.70 max |
| Nitrogen (N) | ≤ 0.10 |
| Iron (Fe) | Balance |
The controlled higher carbon content (0.04–0.10%) combined with titanium stabilization is the defining feature of AISI 321H. Higher carbon improves high-temperature strength and creep resistance, while titanium prevents intergranular corrosion. SHH STEEL carefully controls both carbon and the titanium-to-carbon ratio to meet the requirements of elevated-temperature service under load.
Mechanical Properties
Annealed Condition (typical values)
| Property | Value |
|---|---|
| Tensile Strength | ≥ 515 MPa (75 ksi) |
| Yield Strength (0.2%) | ≥ 205 MPa (30 ksi) |
| Elongation (in 50 mm) | ≥ 40% |
| Hardness | ≤ 217 HB |
| Grain Size | ASTM No. 6 or coarser |
For H grades such as AISI 321H, ASTM A240 requires a controlled grain size of ASTM No. 6 or coarser. This coarser grain structure is essential for optimizing long-term creep resistance at elevated temperatures. SHH STEEL ensures that AISI 321H plates meet the specified grain size requirements in addition to the mechanical property limits.
At elevated temperatures, AISI 321H retains higher strength than standard 321 due to the controlled carbon content and appropriate grain size. SHH STEEL supplies material with consistent high-temperature mechanical properties and verified grain size.
Physical Properties Density is approximately 7.90–8.00 g/cm³. The grade is non-magnetic in the annealed condition. Melting range is approximately 1400–1425°C.
Material Comparison
| Grade | Carbon | Stabilization | Grain Size Control | High-Temp Strength | Intergranular Corrosion Resistance | Typical Preference |
|---|---|---|---|---|---|---|
| AISI 321 | ≤ 0.08 | Titanium | Not mandatory | Good | Excellent | Stabilized high-temp welded service |
| AISI 321H | 0.04–0.10 | Titanium | ASTM No. 6 or coarser | Higher | Excellent | High-temp strength + stabilization |
| AISI 347 | ≤ 0.08 | Niobium | Not mandatory | Good | Excellent | Nb-stabilized high-temp service |
| AISI 304H | 0.04–0.10 | None | ASTM No. 6 or coarser | Higher | Moderate | High-temp strength (no stabilization) |
| AISI 316Ti | ≤ 0.08 | Titanium | Not mandatory | Good | Excellent | Stabilized high-temp chloride service |
| AISI 310H | 0.04–0.10 | None | ASTM No. 6 or coarser | Higher | Moderate | Severe high-temp oxidation |
AISI 321H is selected when improved high-temperature strength and creep resistance are required in addition to titanium stabilization against intergranular corrosion. Compared with standard a240 321, it offers higher strength at elevated temperature. For niobium stabilization, SHH STEEL also supplies a240 347. For severe oxidizing service, a240 310h may be preferred.
Corrosion Resistance
AISI 321H offers good resistance to atmospheric corrosion, fresh water and many mild to moderate chemical environments, similar to standard 321. The titanium stabilization provides excellent resistance to intergranular corrosion after welding or exposure to the sensitization temperature range, even with the higher carbon content.
In chloride-containing environments, AISI 321H can be susceptible to pitting and stress corrosion cracking. For improved pitting resistance, SHH STEEL recommends a240 316l or a240 316ti. For severe high-temperature oxidizing service, a240 310s or a240 310h is preferred.
Weldability
AISI 321H can be welded by standard fusion welding methods. Matching or 321H / 347-type filler metals are preferred to maintain high-temperature strength and stabilization in the weld metal. Due to the higher carbon content, proper welding procedures are important.
The titanium stabilization helps protect against intergranular corrosion in the heat-affected zone. Post-weld solution annealing may be recommended for critical high-temperature service. SHH STEEL recommends controlled welding parameters and post-weld cleaning for optimum performance.
Heat Treatment
AISI 321H is normally supplied in the solution-annealed condition by SHH STEEL.
Recommended solution annealing temperature range is 1050–1150°C (often toward the higher end), followed by rapid cooling. Proper annealing is important to dissolve carbides, achieve the required grain size, ensure effective titanium stabilization, and optimize both room-temperature and elevated-temperature properties. SHH STEEL controls heat treatment to ensure consistent performance and compliance with grain size requirements for high-temperature applications under load.
Surface Finishes
| Finish | Description | Typical Use / Keywords |
|---|---|---|
| No.1 | Hot-rolled, annealed and pickled | AISI 321H No.1 – most common for industrial high-temp plate |
| 2B | Cold-rolled, annealed, pickled, skin-passed | AISI 321H 2B – thinner plates |
| Special | Ground or custom finishes | AISI 321H Special – on request |
SHH STEEL regularly supplies AISI 321H in No.1 finish, which is the preferred condition for most high-temperature plate applications.
Tolerances
Dimensional tolerances for AISI 321H Stainless Steel Plate supplied by SHH STEEL generally conform to ASTM A480 practices.
Typical available size range is thickness 1 mm – 80 mm, width up to 2000–3000 mm, and length up to 12000 mm or cut-to-length. SHH STEEL provides precise dimensional control and can support tighter tolerances when required.
Equivalent Material Grades
| Grade / Designation | Standard / Region | Notes |
|---|---|---|
| AISI 321H | — | — |
| UNS S32109 | Unified Numbering System | — |
| ASTM A240 Type 321H | ASTM A240 | When dual certified |
| 1.4541 related (high C) | EN (Europe) | Closest European grades |
| SUS321H related | JIS (Japan) | Japanese related grades |
| 07Cr18Ni11Ti related | GB/T (China) | Chinese related high-C grades |
| Related 321 / 347 / 321H | Multiple | Standard / Nb-stabilized variants |
Related grades for comparison include a240 321, a240 304, a240 304l, a240 347, a240 316ti and a240 310h.
Applications
AISI 321H is selected for applications requiring both improved high-temperature strength/creep resistance and resistance to intergranular corrosion. Typical applications of AISI 321H include:
| Industry / Sector | Typical Components / Equipment (with keywords) |
|---|---|
| Heat Exchangers & Boilers | AISI 321H heat exchanger components, tubesheets and shells |
| Furnace & Heat Treatment | AISI 321H furnace components, fixtures and supports |
| Power Generation | AISI 321H high-temperature ducting and load-bearing parts |
| Chemical & Process Industry | AISI 321H process equipment operating at elevated temperature |
| Expansion Joints & Bellows | AISI 321H expansion joints requiring strength + stabilization |
| Exhaust Systems | AISI 321H high-temperature exhaust components |
| General High-Temperature Service | AISI 321H equipment under load in the sensitization range |
SHH STEEL supplies AISI 321H for these elevated-temperature applications with consistent quality and verified grain size. For related industry solutions, see our energy industry, petrochemical industry and equipment manufacturing pages. Supporting services include steel cutting services and steel welding services.
Why Choose SHH STEEL
SHH STEEL is a China steel mill-Direct Supply specializing in stainless steel plate and sheet. By working directly with major Chinese stainless steel mills, SHH STEEL supplies AISI 321H with the following advantages:
- Genuine China steel mill-Direct Supply pricing
- Consistent quality and complete heat traceability
- Full Mill Test Certificates (EN 10204 3.1)
- High-carbon titanium-stabilized material with controlled grain size (ASTM No. 6 or coarser) for optimized creep resistance
- Flexible dimensions and surface finishes (including AISI 321H No.1 and AISI 321H 2B)
- Technical support for selection among 321, 321H, 347, 304H and high-temperature grades
- Value-added services including steel cutting services, steel welding services and worldwide shipping service
For more information about our company and full product range, please visit China steel Mill Agent-SHH STEEL.
FAQ
- What is the main advantage of AISI 321H over AISI 321?The controlled higher carbon content (0.04–0.10%) and required grain size of ASTM No. 6 or coarser provide improved high-temperature strength and better creep resistance, while retaining titanium stabilization. SHH STEEL recommends 321H when long-term strength under load at elevated temperature is important.
- Why is grain size controlled for AISI 321H?A coarser grain size (ASTM No. 6 or coarser) improves long-term creep resistance at high temperatures. SHH STEEL ensures compliance with this requirement for all AISI 321H plates.
- How does AISI 321H compare with AISI 347?Both are stabilized grades. 321H uses titanium + higher carbon for strength, while 347 uses niobium. Performance is similar in many applications. SHH STEEL can supply both and help select the better option.
- Is AISI 321H magnetic?Non-magnetic in the annealed condition. SHH STEEL supplies fully annealed material as standard.
- What is the density of AISI 321H?Approximately 7.90–8.00 g/cm³. SHH STEEL provides material certificates confirming physical and mechanical properties, including grain size.
- Can AISI 321H be used in chloride environments?It has limited resistance to pitting in chlorides. For better performance, SHH STEEL recommends a240 316l or a240 316ti.
- Does SHH STEEL supply dual-certified ASTM A240 / AISI 321H material?Yes, SHH STEEL commonly supplies dual-certified material upon request.
Conclusion
AISI 321H Stainless Steel Plate is the high-carbon, titanium-stabilized version of the classic 321 grade. It combines improved high-temperature strength and creep resistance (supported by controlled carbon content and grain size of ASTM No. 6 or coarser) with excellent resistance to intergranular corrosion after welding. It is an outstanding choice for heat exchangers, furnace components, expansion joints and other applications requiring long-term performance under load at elevated temperatures.
As a professional China steel mill-Direct Supply, SHH STEEL provides high-quality AISI 321H Stainless Steel Plate with competitive pricing, full certification, verified grain size and complete technical support.
Contact SHH STEEL today for stock availability, surface finish options (including AISI 321H No.1 and AISI 321H 2B), or a competitive quotation.
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