ASTM A537 Class 2 is a heat-treated carbon-manganese-silicon steel plate for fusion-welded pressure vessels and structures, offering higher strength than Class 1 due to quenching and tempering, making it ideal for oil, gas, and petrochemical applications needing improved toughness at moderate to low temperatures. It's known for good strength, toughness, and weldability, with typical uses in tanks, boilers, and cryogenic storage.
Chemical Composition
| Grade | C | Si | Mn | P | S | Cr | Mo | Ni | Cu | |
|---|---|---|---|---|---|---|---|---|---|---|
| ¡Ü 40 mm | > 40 mm | |||||||||
| A537 Class 2 | 0.24 | 0.15/0.50 | 0.70/1.35 | 1.00/1.60 | 0.035 | 0.035 | 0.025 | 0.080 | 0.25 | 0.35 |
Mechanical Properties
| Grade | Yield (MPa) | Tensile (MPa) | Elongation | Thickness | |
|---|---|---|---|---|---|
| A50mm | A200mm | ||||
| A537 Class 2 | 415 | 550/690 | 22% | - | ¡Ü 65 |
| 380 | 515/655 | 22% | - | > 65 ¡Ü 100 | |
| 315 | 485/620 | 22% | - | > 100 ¡Ü 150 | |
processing
1. Steelmaking and Rolling
Melting & Refining: The steel is produced using Electric Arc Furnaces (EAF) or Basic Oxygen Furnaces (BOF), followed by Ladle Refining (LF) and Vacuum Degassing (VD) to ensure high purity and low sulfur/phosphorus content.
Fine Grain Practice: The steel must be killed and manufactured to a fine austenitic grain size.
Hot Rolling: Slabs are heated and rolled to the target thickness. While Thermo-Mechanical Controlled Processing (TMCP) may be used, the final properties are primarily achieved through subsequent heat treatment.
2. Core Heat Treatment (Quenched & Tempered)
This is the critical stage that differentiates Class 2 from Class 1 (which is only normalized).
Austenitizing/Quenching: The plates are heated to a uniform temperature (typically around 860°C - 880°C) and then rapidly cooled using a water spray or immersion quenching system. This process hardens the steel by transforming the microstructure.
Tempering: The quenched plates are reheated to a temperature of at least 595°C (1100°F) and held for a specified duration (usually 30 minutes per inch of thickness). This restores toughness and ductility while maintaining high yield strength.
3. Inspection and Quality Control
To ensure compliance with the ASTM A537/A537M standard, the following tests are mandatory:
Mechanical Testing: Tensile tests (to verify Yield Strength ≥415 MPa and Tensile Strength 550-690 MPa) and Elongation tests.
Impact Testing: Charpy V-Notch (CVN) impact tests are frequently required to ensure low-temperature toughness.
Nondestructive Examination (NDE): Ultrasonic Testing (UT) is performed per ASTM A435 or A578 to detect internal laminations or defects.
4. Downstream Fabrication
For manufacturers building pressure vessels or tanks:
Cutting: CNC Flame or Plasma cutting is common. Preheating may be required for thick plates to prevent edge cracking.
Cold Forming: A537 Cl.2 has good formability; however, the minimum bending radius is larger than that of mild steel due to its higher strength.
Welding: Highly weldable using standard methods like SMAW, GMAW, or SAW. Low-hydrogen electrodes (e.g., E8018 series) are recommended to match the base metal's strength.
Post-Weld Heat Treatment (PWHT): Depending on the vessel code (e.g., ASME Section VIII), PWHT may be required to relieve stresses, though care must be taken not to exceed the original tempering temperature to avoid softening the material.
Why Choose Us :
You can get the perfect material according to your requirement at the least possible price.
We also offer Reworks, FOB, CFR, CIF, and door to door delivery prices. We suggest you to do deal for shipping which will be quite economical.
The materials we provide are completely verifiable, right from raw material test certificate to the final dimensional statement.(Reports will show on requirement)
We guarantee to give a response within 24hours(usually in the same hour)
You can get stock alternatives, mill deliveries with minimizing manufacturing time.
We are fully dedicated to our customers. If it will not possible to meet your requirements after examining all options, we will not mislead you by making false promises which will create good customer relations.
Get an valued quotation for ASTM A537 Class 2, Contact GNEE Steel.
Does A537 Class 2 require post-weld heat treatment (PWHT)?
PWHT is not mandatory but recommended for thick sections (>1.5 inches) or high-stress applications. It relieves welding residual stresses, reduces cracking risk, and improves dimensional stability. PWHT involves heating to 1100-1200°F (593-649°C) and holding before cooling.
What is the modulus of elasticity of A537 Class 2?
Its modulus of elasticity is approximately 29 × 10⁶ psi (200 GPa), standard for carbon and low-alloy steels. This value is used in structural design to calculate deflection and stress under load, ensuring pressure vessels maintain shape and integrity.
How is A537 Class 2 inspected for quality?
Quality inspection includes chemical analysis (spectroscopy), mechanical testing (tensile, impact, bend), ultrasonic testing (for internal defects), and visual inspection. Certificates (MTC) are provided to confirm compliance with ASTM A537 standards, ensuring material reliability.
What is the maximum operating temperature for A537 Class 2?
It can operate at temperatures up to 650°F (343°C). Beyond this, strength decreases, and creep may occur. For higher temperatures, heat-resistant alloys like A387 are preferred. Proper thermal design prevents overheating and material degradation.
Is A537 Class 2 magnetic?
Yes, it is magnetic due to its ferritic microstructure (body-centered cubic). This property allows magnetic particle inspection (MPI) for surface defects, a common non-destructive testing method in pressure vessel manufacturing and maintenance.
What is the difference between A537 Class 2 and A516 Gr. 70?
A537 Class 2 is normalized, while A516 Gr. 70 is as-rolled or normalized. Class 2 has higher yield strength (38 vs. 38 ksi, same yield but stricter impact tests) and better low-temperature toughness, suitable for more demanding pressure applications.
How is A537 Class 2 stored to prevent degradation?
It should be stored in a dry, covered area to avoid moisture and rust. Plates are stacked on wooden supports to allow air circulation, preventing contact with wet surfaces. Protective films or oils may be applied for long-term storage to preserve surface quality.
Can A537 Class 2 be used in marine applications?
Yes, it is used in marine pressure vessels, ship hulls, and offshore structures. Its strength and weldability suit marine environments, but corrosion protection (paint, cathodic protection) is essential to resist saltwater corrosion and ensure long-term durability.
What is the Charpy impact energy requirement for A537 Class 2?
At -20°F (-29°C), three specimens must have an average CVN impact energy of 20 ft-lb (27 J), with no individual value below 15 ft-lb (20 J). This ensures toughness to withstand sudden impacts or low-temperature stress without brittle failure.
What is the yield-to-tensile ratio of A537 Class 2?
The yield-to-tensile ratio is approximately 0.63 (38 ksi yield / 60 ksi tensile). A moderate ratio indicates good ductility and reserve strength, allowing the material to deform before reaching tensile failure, critical for pressure vessel safety.