ASTM A335 P5

ASTM A335 P5

ASTM A335 P5 (ASME SA335 P5) is an intermediate alloy chromium-molybdenum steel (Cr-Mo steel), a 5% chromium - 0.5% molybdenum alloy grade under the ASTM A335/ASME SA335 standard. Its typical composition is 4-6% Cr and 0.45-0.65% Mo, making it one of the higher-chromium grades in the Cr-Mo alloy steel series. It offers significant advantages in high-temperature oxidation resistance and corrosion resistance. This material is specifically designed for high-temperature, high-pressure, and corrosive service conditions and is a classic choice for high-temperature pressure-bearing equipment in fields such as oil refining, petrochemicals, and power generation.
The core characteristics of ASTM A335 P5 lie in the balanced combination of excellent high-temperature oxidation resistance and good high-temperature strength. This grade has a low carbon content (approximately 0.15% maximum), and its 5% chromium content significantly enhances the material's oxidation and corrosion resistance at elevated temperatures. This makes it exhibit excellent microstructural stability and high-temperature oxidation resistance in service environments within the 500-600°C temperature range. Additionally, the addition of 0.5% molybdenum (Mo) further improves the material's high-temperature creep rupture strength, making it suitable for harsh conditions such as catalytic cracking units, hydrotreating plants, and high-temperature steam pipelines in refineries. P5 is one of the representative high-chromium grades in the ASTM A335 series, with products conforming to international standards such as ASTM A335/ASME SA335 and ASTM A213 (corresponding to T5 tubing).
Key Features: P5 is a grade in the A335 chromium-molybdenum steel series with a higher chromium content (4-6%). It offers significantly better high-temperature oxidation resistance and corrosion resistance than P1 and P11. Suitable for high-temperature (500-600°C) and sulfur-containing corrosive environments, it is one of the preferred materials for high-temperature process piping in oil refining and petrochemical industries.
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Description
Technical Parameters

Products Features

High-Temperature Oxidation Resistance

Excellent high-temperature oxidation resistance and corrosion resistance (core advantage)

The core advantage of ASTM A335 P5 lies in its excellent high-temperature oxidation resistance and corrosion resistance. Thanks to the addition of 4-6% chromium (Cr), P5 can form a dense Cr₂O₃ oxide film at high temperatures, effectively resisting high-temperature oxidation and thermal corrosion. Its upper limit for oxidation resistance reaches 550-600°C, significantly outperforming P1 (≤450°C) and P11 (≤538°C). In high-temperature sulfur-containing environments of refineries, P5 exhibits superior corrosion resistance compared to low-chromium grades, effectively withstanding high-temperature sulfidation corrosion and combined oxidation-sulfidation corrosion. With a minimum tensile strength of 415 MPa and a minimum yield strength of 205 MPa, it is on par with P1 and P11 in terms of strength level but offers a notable advantage in high-temperature oxidation resistance.

High-Temperature Corrosion Resistance

Good high-temperature strength and creep resistance

ASTM A335 P5 maintains good strength levels at high temperatures. Thanks to the addition of 0.5% molybdenum (Mo) and higher chromium content, P5 exhibits excellent high-temperature creep rupture strength in the temperature range of 500-600°C. Under conditions at 550°C, P5 offers better oxidation resistance and high-temperature strength compared to P11, making it suitable for high-temperature and high-pressure piping systems operating at higher temperature grades. Its high-temperature strength retention is comparable to that of P11, but it has a higher upper limit for oxidation resistance temperature, allowing for long-term service in more severe high-temperature environments.

High Stability

Good machinability and formability

ASTM A335 P5 exhibits good cold and hot working properties, allowing for various forming processes such as hot bending, cold bending, and forging. With a moderate alloy content, it demonstrates excellent formability during cold bending, making it suitable for manufacturing pipe fittings like elbows, tees, and reducers. It should be noted that due to its higher chromium content, P5 has a slightly greater tendency for work hardening compared to P1/P11. Therefore, it is recommended to include appropriate intermediate annealing steps during forming processes. Its machinability is comparable to that of P11, and conventional machining methods can be employed for processing.

Good Processability

Good welding performance and post-weld heat treatment requirements

ASTM A335 P5 exhibits good weldability. However, due to its higher chromium content (4-6%), it has a slightly greater tendency for hardening in the heat-affected zone compared to P1/P11, thus requiring more stringent welding procedures and post-weld heat treatment (PWHT). It is recommended that preheating temperature before welding be 150-250°C. After welding, PWHT should be performed by heating to 700-760°C, holding at temperature, and then cooling slowly to relieve residual welding stresses and soften the heat-affected zone, ensuring the toughness and crack resistance of the welded joint.

High-Temperature Oxidation Resistance

Good organizational stability and long-term service reliability

ASTM A335 P5 exhibits good microstructural stability during long-term service at temperatures ≤600℃. Its higher chromium content effectively enhances the material's oxidation resistance and high-temperature corrosion resistance. The composition design of 5%Cr-0.5%Mo ensures microstructural stability during long-term high-temperature service. After normalizing and tempering (N+T) heat treatment, P5 obtains a uniform and fine ferrite + carbide microstructure, guaranteeing microstructural stability and reliability under high-temperature service conditions.

Technical Specifications

Chemical Composition(ASTM A335 / ASME SA335)

 

Element

Standard requirements

Note

C

≤ 0.15%

Low-carbon design ensures weldability and toughness

Mn

0.30 - 0.60%

Solid solution strengthening, improve strength

P

≤ 0.025%

Harmful elements, strictly controlled

S

≤ 0.025%

Harmful elements, strictly controlled

Si

≤ 0.50%

Deoxidizer, improve high-temperature oxidation resistance

Cr

4.00 - 6.00%

Core elements that provide basic antioxidant and corrosion resistance

Mo

0.45 - 0.65%

Core elements to improve high-temperature creep fracture strength

Fe

Remaining quantity(≈ 93%)

Matrix element

Physical Properties

 

Performance

Numerical Value/Range

Test conditions

Density

≈ 7.75 g/cm³

Room Temperature (20°C)

Melting Point

≈ 1390-1430°C

-

Electrical resistance

≈ 0.40 μΩ·m

Room Temperature

Thermal Conductivity

≈ 34 W/(m·K)

Room Temperature

Coefficient of Thermal Expansion (20-100°C)

≈ 11.6 × 10⁻⁶ /K

-

Elastic modulus (Young's modulus)

≈ 200 GPa

Room Temperature

Poisson's ratio

≈ 0.28

Room Temperature

Magnetism

Ferromagnetic

Ferrite structure, which is magnetic

Mechanical Properties (Normalized + Tempered, Typical Values, ASTM A335)

 

Performance

Typical value

Implementation standards

Tensile Strength

≥ 415 MPa

ASTM A335

Yield Strength (0.2% Offset)

≥ 205 MPa

ASTM A335

Elongation (gauge length 2in/50mm)

≥ 30%

ASTM A335

Hardness

≤ 217 HB (typical value)

-

Note: The strength level of P5 is the same as that of P1/P11 (≥415 MPa). However, its core advantage lies in the excellent high-temperature oxidation resistance and corrosion resistance brought by its 4-6% chromium content, rather than enhanced strength. For higher strength or higher temperature grades, it is recommended to use P91.

High-temperature performance

 
 

High-temperature Tensile Strength Retention (Typical Value):

ASTM A335 P5 maintains good strength levels at high temperatures and is suitable for long-term high-temperature service conditions up to 600°C:

Temperature

Tensile strength (MPa, approximately)

Performance retention rate

Room temperature (20°C)

≥ 415

100%

400°C

≈ 370

≥ 89%

450°C

≈ 340

≥ 82%

500°C

≈ 280

≥ 67%

Long-term Thermal Stability and Microstructural Stability

ASTM A335 P5 exhibits good microstructural stability during long-term service at temperatures ≤600°C. The addition of 4-6% Cr effectively enhances high-temperature oxidation resistance and thermal corrosion resistance. However, microstructural stability decreases and oxidation resistance is reduced when used for long-term service above 620°C. It is not recommended for long-term service above 620°C. For higher temperature grades, it is suggested to select P91 or P92.

Heat treatment system

The final performance of ASTM A335 P5 is highly dependent on the heat treatment regime, with common specifications as follows:

1. Normalizing Treatment (Normalizing)
Heat to 925-955°C, hold for a sufficient time (approximately 1 hour per inch of wall thickness), then air cool. This results in a uniform, fine-grained ferrite + carbide microstructure, preparing for subsequent tempering.

2. Tempering treatment (Tempering)
Heat to 700-760°C, hold for sufficient time, then air cool. This eliminates stresses induced by normalizing, optimizes toughness and plasticity, and achieves the final service properties.

3. Full Annealing (Optional)
Heat to 840-870°C, hold at temperature, then furnace cool to approximately 650°C, followed by air cooling to room temperature. This is used to eliminate cold working stresses or improve cold working formability.

Attention:

Post-weld heat treatment (PWHT) is recommended after welding. It involves heating to 700-760°C, holding at temperature, and then slow cooling to eliminate residual welding stresses and soften the heat-affected zone.

Due to its higher chromium content, P5 has a greater tendency to harden in the weld heat-affected zone compared to P1/P11. It is recommended to strictly control welding heat input and preheating temperature.

The heat treatment temperature and time must be strictly controlled to avoid grain coarsening or performance fluctuations.

Applicable Media

High-temperature steam:

Main steam pipelines of power plants (≤600°C), boiler superheater tubes, reheater tubes

Petroleum refining media:

High-temperature sulfur-containing process pipelines for atmospheric and vacuum distillation, catalytic cracking, hydrotreating, delayed coking, etc.

High-temperature sulfur-containing media:

High-temperature sulfur-containing oil and gas media, acidic media environments in refineries

High-temperature process gases:

High-temperature and high-pressure pipelines of chemical facilities for ammonia synthesis, methanol production, etc.

High-temperature heat transfer media:

Heat transfer oil pipelines, high-temperature heat transfer systems

Note: ASTM A335 P5 is not applicable to strongly corrosive media such as strongly oxidizing acids (e.g., concentrated nitric acid) and high-temperature, high-concentration chlorides. Its upper oxidation temperature limit is approximately 600°C; P91 or P92 is recommended above this temperature. In high-temperature, high-pressure hydrogen-containing environments (e.g., hydroprocessing units), hydrogen corrosion risk should be assessed. Typically, P5 is suitable for conditions with lower hydrogen partial pressure or lower temperatures.

Steel Plate Processing
Steel Coil Processing
Steel Pipe Processing
Steel Bar Processing
 

ASTM A335 P5 is suitable for high-temperature (500-600°C) service in sulfur-containing corrosive environments. It is one of the preferred materials for high-temperature process piping in the oil refining and petrochemical industries, recommended for use in the following areas:

 

Application Fields

  •  

    Petroleum Refining (Core Application)
    ● High-temperature process pipelines for catalytic cracking units
    ● High-temperature and high-pressure pipelines for hydrotreating/hydrocracking units
    ● High-temperature pipelines of the atmospheric and vacuum distillation unit
    ● Delayed Coking Unit Process Piping
    ● Refinery heater tubes, heat exchanger tubes

  •  

    Petrochemical Engineering (Core Applications)
    ● High-temperature pipelines in ethylene cracking units
    ● Aromatics unit high-temperature process piping
    ● Petrochemical heating furnace tube system

  •  

    Fossil fuel power generation
    ● Main Steam Piping for Subcritical/Supercritical Power Plants (≤600°C)
    ● Superheater tubes, reheater tubes
    ● High-temperature steam pipeline system

  •  

    High-temperature and high-pressure pipe fittings
    ● High-temperature elbows, tees, and reducers
    ● Forged pipe fittings, flanges

Delivery and Customization

We offer flexible and reliable supply chain solutions to ensure you receive ASTM A335 P5 alloy steel pipes that perfectly match your project requirements.
Customizable material forms
We support producing various basic and special shapes according to drawings or specifications.

Form

19
Seamless Steel Pipe
7
Large-diameter Thick-walled Pipe
9
Alloy Steel Pipe

Conventional Range

Outer Diameter: 10.3 - 1067 mm; Wall Thickness: 1 - 150 mm

Outer Diameter: 219 - 1067 mm; Wall Thickness: 20 - 150 mm

Outer Diameter: 10.3 - 610 mm; Wall Thickness: 1 - 50 mm

Customization Capability

Hot-rolled / cold-drawn seamless tubes, fixed-length cutting, bevel machining, pipe end threads, special heat treatment conditions (normalizing + tempering / annealing)

Hot expansion, fixed-length cutting, bevel machining, special heat treatment conditions

Cold-drawn precision tubes, fixed-length cutting, special surface treatment

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Strict Quality Control at Every Stage

Full traceability across key QC checkpoints throughout production. 100% compliant with ASTM/ASME, EN, and GB standards. Material test reports available with every shipment.

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10+ years exporting to Europe, North America, Southeast Asia & Middle East with waterproof and anti-rust protection, combined with flexible shipping options ensures safe and on-time arrival.

Complete Export Documentation

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FAQ

Q: What are the main advantages of ASTM A335 P5?

 

Q: What is the difference between ASTM A335 P5 and P11? How to choose between them?

 

Q: What is the difference between ASTM A335 P5 and P1? How to choose between them?

 

Q: What is the maximum service temperature for ASTM A335 P5?

 

Q: What is the welding performance of ASTM A335 P5?

 

Q: What is the corrosion resistance of ASTM A335 P5?

 

 

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