ASTM A516 Grade 70 is a robust, pressure vessel quality (PVQ) carbon steel plate designed for moderate to lower-temperature service, known for its strength, weldability, and notch toughness, making it ideal for boilers, storage tanks, and chemical processing equipment. It offers higher strength than other A516 grades (like 55, 60, 65) with a tensile strength of 70-90 ksi (485-620 MPa).
specification
|
Standard/Grade |
Thickness Range |
Width Range |
Length Range |
Supply Condition |
|---|---|---|---|---|
|
ASTM A516 GR 70 |
6mm–300mm |
1500mm–4050mm |
3000mm–15000mm |
As-rolled (≤40mm), Normalized (>40mm) |
Chemical Composition
|
Standard/Grade |
C (Max %) |
Si (%) |
Mn (%) |
P (Max %) |
S (Max %) |
Ni (Max %) |
Cr (Max %) |
Mo (Max %) |
|---|---|---|---|---|---|---|---|---|
|
ASTM A516 GR 70 |
0.27 |
0.15–0.40 |
0.85–1.20 |
0.035 |
0.035 |
0.40 (opt) |
0.30 (opt) |
0.08 (opt) |
Mechanical Properties of ASTM A516 Grade 70
| Description | Grade 70 |
|---|---|
| Tensile strength (ksi) | 70-90 |
| Tensile strength (MPa) | 485-620 |
| Yield strength (ksi) | 38 |
| Yield strength (MPa) | 260 |
| Elongation in 200mm (min)(%) | 17 |
| Elongation in 50mm (min) (%) | 21 |
| Thickness (max)(mm) | 205 |
processing flow
1. Steelmaking & Plate Production
Melting: The steel must be "killed" and made to a fine austenitic grain size practice.
Casting & Rolling: Raw steel is cast into slabs and then hot-rolled into plates.
Heat Treatment (Mill Level):
Normalizing: Recommended for plates over 1.5 inches (40 mm) thick or when improved toughness is required at low temperatures. The plate is heated to 1,650–1,750°F (900–950°C) and air-cooled to refine grain structure.
As-Rolled: Thinner plates (≤ 1.5 inches) may be supplied in the as-rolled condition unless normalizing is specified.
2. Primary Processing
Cutting: Common methods include Oxy-fuel flame cutting, Plasma cutting, or Laser cutting depending on thickness and precision needs.
Surface Preparation: Processes like Shot blasting are used to remove mill scale and oxidation, ensuring optimal weldability.
Edge Preparation: Beveling and Chamfering are performed to prepare plate edges for welding joints.
3. Fabrication & Forming
Cold/Hot Forming: Plates are rolled or pressed into cylindrical shells or formed into vessel heads.
Machining: A516-70 machines relatively well but can work-harden. Carbide or cobalt tools are used for drilling, tapping, and milling with proper lubrication to manage heat.
4. Welding
Processes: Highly weldable using standard methods such as SMAW, GMAW, GTAW, and SAW.
Filler Metals: Must offer compatible mechanical properties and impact toughness (e.g., >20 ft-lb at -20°F or -50°F).
Preheating: Often required for thicker sections to prevent cracking.
5. Post-Fabrication Treatment
Post-Weld Heat Treatment (PWHT): Essential for stress relief in thick-walled vessels or specific service conditions.
Temperature: Typically 1,100–1,250°F (595–675°C).
Holding Time: Standard practice is 1 hour per inch of material thickness.
6. Inspection & Testing
Non-Destructive Testing (NDT): Includes Ultrasonic Examination (UT) (per ASTM A435 or A578) and Magnetic Particle Examination to check for internal flaws or surface cracks.
Mechanical Testing: Final verification of Tensile Strength (70–90 ksi) and Yield Strength (min 38 ksi) through tension tests and Charpy V-notch impact tests.
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What is the maximum plate thickness for ASTM A516 GR 70?
Standard max thickness is 200 mm (7.87 inches). Thicker plates may need special processing and additional mechanical property verification.
What is ASTM A516 GR 70?
It is a carbon steel plate standard for pressure vessels, widely used in moderate/low-temperature service. It offers excellent weldability and notch toughness, suitable for boilers and storage tanks.
What is the minimum tensile strength of ASTM A516 GR 70?
Its minimum tensile strength is 70 ksi (485 MPa), with a minimum yield strength of 38 ksi (260 MPa), ensuring good mechanical performance for pressure-bearing applications.
What temperature range is ASTM A516 GR 70 suitable for?
It performs well from -29°C (-20°F) to 343°C (650°F). For lower temps, supplementary toughness tests may be required per project specs.
What standards are equivalent to ASTM A516 GR 70?
EN 10028-2 P265GH (Europe) and GB 713 Q345R (China) are approximate equivalents, but technical specs vary; cross-verification is needed.
Can ASTM A516 GR 70 be used in corrosive environments?
It resists mild corrosion but not harsh media. For corrosive conditions, coating, cladding, or upgrading to alloy steels is recommended.
What heat treatment is ASTM A516 GR 70 subjected to?
It's usually supplied in normalized, quenched-and-tempered, or as-rolled condition. Normalization enhances uniformity and toughness.
What is the hardness requirement for ASTM A516 GR 70?
No fixed standard hardness, but typical Brinell hardness is 130-180 HB. Welded zones should be checked to avoid excessive hardness.
Can ASTM A516 GR 70 be used for high-pressure vessels?
Yes, for moderate-high pressure. Its strength and toughness meet ASME BPVC requirements, making it ideal for pressure vessels in various industries.
What is the density of ASTM A516 GR 70?
Its density is about 7.85 g/cm³ (0.284 lb/in³), same as standard carbon steels, facilitating weight calculation for equipment design.
How to inspect ASTM A516 GR 70 plates?
Inspections include chemical analysis, mechanical tests (tensile, bend), visual check, ultrasonic testing, and impact tests if required.