ASTM A182 F91 P91 Heat Resistant Alloy Steel Round Bar
Short Description:
ASTM A182 F91 / P91 heat resistant alloy steel round bar is a 9Cr-1Mo-V-Nb steel for high-temperature power plant, boiler, valve, flange and pressure equipment parts. Custom diameter, cutting, machining, heat treatment, MTC and EN 10204 3.1 available.
ASTM A182 F91 P91 Heat Resistant Alloy Steel Round Bar is a 9Cr-1Mo-V-Nb alloy steel bar used for high-temperature and high-pressure components in power generation, boiler systems, petrochemical equipment, valves, flanges, forged fittings, pressure equipment parts and machined components. This grade is often associated with P91 pipe material, but for bar or forged bar products, ASTM A182 F91 or ASTM A336 F91 references are more appropriate than ASTM A335, which is a seamless pipe specification.
SAKY STEEL supplies F91 / P91 heat resistant alloy steel round bar and forged bar in black, peeled, turned, ground or machined condition according to project requirements. Custom diameter, length, cutting, machining allowance, heat treatment, hardness testing, dimensional inspection, ultrasonic testing when specified, MTC and EN 10204 3.1 documentation can be provided according to the purchase order.
Product Parameters
| Item | Product Details |
|---|---|
| Product Name | ASTM A182 F91 P91 Heat Resistant Alloy Steel Round Bar |
| Grade | F91 / P91 / 9Cr-1Mo-V-Nb |
| UNS Designation | UNS K90901 Reference |
| Material Family | Heat resistant chromium-molybdenum alloy steel |
| Product Shape | Round bar and forged round bar |
| Applicable Standard | ASTM A182 / ASTM A336 Reference |
| Related Pipe Material | ASTM A335 P91 pipe material family |
| Diameter | Regular and custom diameters by order |
| Length | 1000–6000 mm or cut to length |
| Surface Finish | Black, peeled, turned, ground, machined |
| Heat Treatment | Normalized and tempered or as specified |
| Available Services | Cutting, turning, peeling, grinding, machining, UT when specified |
| Certificates | MTC, EN 10204 3.1, dimensional and inspection reports |
Chemical Composition
F91 / P91 is commonly described as a modified 9Cr-1Mo alloy steel with vanadium, niobium and nitrogen additions. Chromium supports oxidation resistance, molybdenum improves high-temperature strength, and vanadium-niobium-nitrogen additions help stabilize the tempered martensitic structure.
| Element | Typical Reference Content | Technical Function |
|---|---|---|
| Carbon | About 0.08–0.12% | Supports strength and tempered martensitic structure |
| Chromium | About 8.00–9.50% | Improves oxidation resistance and high-temperature behavior |
| Molybdenum | About 0.85–1.05% | Improves creep strength and thermal stability |
| Vanadium | Controlled addition | Supports precipitation strengthening |
| Niobium | Controlled addition | Helps stabilize microstructure during service |
| Nitrogen | Controlled addition | Works with V and Nb for strengthening effects |
| Manganese | Controlled range | Supports melting control and strength |
| Silicon | Controlled maximum | Supports deoxidation and oxidation behavior |
| Phosphorus / Sulfur | Controlled maximum | Restricted to support weldability and service reliability |
| Iron | Balance | Base metal matrix |
Actual chemical composition shall be confirmed by the applicable product specification and MTC.
Mechanical and High-Temperature Properties
Mechanical properties of F91 / P91 alloy steel bar depend on diameter, forging reduction, heat treatment, test direction, hardness condition and applicable code requirement. The following values are typical references and should not replace order-specific MTC or project acceptance criteria.
| Property | Typical Reference | Condition | Engineering Meaning |
|---|---|---|---|
| Tensile Strength | Specification dependent | Normalized and tempered | Supports high-temperature pressure components |
| Yield Strength | Specification dependent | Room temperature test | Important for valve, flange and forged parts |
| Hardness | Controlled by specification and heat treatment | After tempering | Used to verify heat-treatment condition |
| Creep Strength | High for 9Cr-1Mo-V-Nb steel | Elevated temperature service | Key reason for power plant applications |
| Oxidation Resistance | Improved by chromium content | High-temperature air or steam | Supports boiler and turbine-related parts |
| Heat Treatment | Normalized and tempered reference | Final delivery condition | Controls tempered martensitic structure |
| Machinability | Moderate alloy steel machinability | Normalized and tempered bar | Suitable for valves, flanges and machined parts |
| Density | About 7.8 g/cm³ reference | Room temperature | Used for bar weight calculation |
Common Size Table
| Diameter | Length | Surface | Processing | Typical Use |
|---|---|---|---|---|
| Ø20–80 mm | 1000–6000 mm | Peeled or turned | Cutting and machining | Small valve and pressure parts |
| Ø85–180 mm | Custom cut length | Turned or black | Saw cut and rough machining | Flange, valve and forged component blanks |
| Ø185–350 mm | Made to order | Forged and turned | UT when specified | Large high-temperature pressure parts |
| Above Ø350 mm | Project specific | Forged or machined | Technical review required | Heavy forged components |
Different Specifications Comparison
Bar Surface and Processing Comparison
| Condition | Main Feature | Recommended Use | Purchase Advice |
|---|---|---|---|
| Black Bar | Mill or forged surface | Rough machining and forging blanks | Confirm machining allowance |
| Peeled Bar | Scale-free surface | Machined pressure components | Useful for CNC processing |
| Turned Bar | Controlled diameter and surface | Valve stems, shafts and machined parts | State tolerance and allowance |
| Ground Bar | Smooth surface and tighter tolerance | Precision machined components | State h9, h8 or drawing tolerance |
| Forged Bar | Suitable for large section parts | Flange, valve and pressure equipment blanks | UT and forging ratio may be specified |
Comparison with Related Heat Resistant Alloy Steel Grades
| Grade | Main Alloy System | Main Strength | Typical Selection |
|---|---|---|---|
| F11 / P11 | 1.25Cr-0.5Mo type | General elevated-temperature service | Lower temperature and pressure parts |
| F22 / P22 | 2.25Cr-1Mo type | Good creep and oxidation resistance | Boiler and petrochemical components |
| F91 / P91 | 9Cr-1Mo-V-Nb type | Higher creep strength and oxidation resistance | High-temperature valves, flanges and pressure parts |
| F92 / P92 | Advanced 9Cr alloy type | Enhanced creep performance in selected designs | Advanced power plant applications when specified |
Equivalent Standards and International Names
| System | Designation | Relationship |
|---|---|---|
| ASTM Forging Standard | ASTM A182 F91 | Forged or rolled alloy steel components for high-temperature service |
| ASME Reference | ASME SA182 F91 | Boiler and pressure vessel code reference when specified |
| ASTM Forging Reference | ASTM A336 F91 | Large alloy steel forgings when specified |
| Related Pipe Standard | ASTM A335 P91 | Seamless pipe standard, not bar standard |
| UNS | K90901 Reference | Common UNS reference for F91/P91 material family |
| Common Name | 9Cr-1Mo-V-Nb | Modified high-temperature alloy steel family |
Production Process Flow
Alloying materials are selected according to F91 / P91 chemistry requirements.
Chemistry, cleanliness and residual elements are controlled during steelmaking.
Billets or ingots are prepared for rolling or forging.
The material is processed into round bar or forged bar form.
Normalized and tempered treatment is applied according to specification requirements.
Bars can be peeled, turned, ground, machined or cut to length.
Dimensions, surface, hardness, chemistry and traceability are checked.
Heat-number marking and export packing are prepared.
Product Inspection
| Inspection | Method | Purpose |
|---|---|---|
| Chemical Analysis | Laboratory analysis or MTC review | Confirm F91 / P91 alloy composition |
| Mechanical Test | Tensile and related testing when required | Verify strength and ductility |
| Hardness Test | HB / HRC / HRB as applicable | Confirm heat treatment condition |
| Dimensional Inspection | Diameter, length and straightness check | Verify ordered size and tolerance |
| Ultrasonic Testing | UT when specified | Evaluate internal soundness in suitable sizes |
| PMI | Positive material identification | Available when specified for alloy verification |
| Surface Inspection | Visual and finish inspection | Check surface quality before shipment |
| Traceability Review | Heat number and marking verification | Link product to MTC and EN 10204 3.1 |
Product Packaging
Bars can be protected with anti-rust oil, VCI paper, film or waterproof wrapping.
Steel straps, separators and padding reduce movement and scratching.
Ground or machined bars can receive end caps or padded protection.
Export packing is selected according to bar diameter, length and weight.
Grade, size, heat number and customer shipping marks can be retained.
Applications, Core Performance and Fabrication
Primary Applications
- High-temperature valve components
- Forged flange and fitting blanks
- Power plant boiler and steam system components
- Pressure equipment machined parts
- Petrochemical high-temperature equipment parts
- Heat resistant shafts, stems and custom forged parts
High-Temperature Performance
F91 / P91 alloy steel bar is valued for creep strength, oxidation resistance and long-term microstructure stability in elevated-temperature service. Its 9Cr-1Mo-V-Nb alloy design makes it suitable for demanding power plant and pressure equipment applications.
Machining
P91 / F91 round bar can be cut, turned, drilled, bored, milled and ground according to drawing requirements. Due to alloy content and heat-treated condition, suitable cutting tools, rigid setup and controlled machining parameters are recommended.
Welding
Welding of F91 / P91 components requires qualified welding procedures, controlled preheat, controlled interpass temperature and proper post-weld heat treatment. Welding procedure qualification and hardness control are important for high-temperature service reliability.
Heat Treatment
F91 / P91 bar is generally supplied in normalized and tempered condition or according to the governing specification. Improper heat treatment may affect strength, hardness and creep performance, so the applicable code and project requirement should be followed.
Why Choose SAKY STEEL?
Diameter, length, surface finish and machining allowance can be supplied according to drawings.
Material identification can be maintained from documentation to final packing.
MTC (Mill Test Certificate / 质保书) can be provided according to the purchase order.
EN 10204 3.1 documentation is available when specified by the order.
Hardness, dimensional, PMI, mechanical and UT inspection can be arranged when specified.
Bundles, wooden cases, pallets and customer shipping marks can be arranged.
FAQ
Is ASTM A335 P91 a bar standard?
No. ASTM A335 P91 is mainly used for seamless ferritic alloy steel pipe for high-temperature service. For round bar or forged bar, ASTM A182 F91 or ASTM A336 F91 is more suitable depending on the product form and project requirement.
What is F91 / P91 alloy steel bar?
F91 / P91 alloy steel bar is a 9Cr-1Mo-V-Nb heat resistant alloy steel used for high-temperature valves, flanges, pressure equipment parts and machined components.
Is P91 stainless steel?
No. P91 is a heat resistant alloy steel, not a stainless steel. Although it contains chromium, it still requires anti-rust protection during storage and transport.
What is the main advantage of P91 bar?
The main advantage is high-temperature creep strength and oxidation resistance. It is used where long-term strength is needed under heat and pressure.
Can P91 / F91 bar be machined?
Yes. P91 / F91 bar can be machined into valve parts, flange blanks, shafts and pressure equipment components. Machining allowance, tolerance and surface finish should be specified before production.
Can P91 / F91 components be welded?
Yes, but welding requires qualified procedures, controlled preheat, controlled interpass temperature and post-weld heat treatment. Welding should follow the applicable code and project specification.
Can MTC and EN 10204 3.1 be provided?
SAKY STEEL can provide MTC and EN 10204 3.1 documentation according to the purchase order. Hardness, dimensional, PMI, mechanical or UT reports may also be arranged when specified.
