ASTM A516/A516M is a standard for carbon steel plates used in pressure vessels with medium to low-temperature toughness, established by ASTM International. It is widely applied in the manufacturing of pressure vessels and pressure-bearing equipment in industries such as petroleum, chemical, natural gas, power, and shipbuilding. Its core characteristic is its ability to maintain excellent strength, toughness, and weldability in medium to low-temperature environments, making it particularly suitable for applications involving impact loads.
According to different strength levels, the plates are available in four grades:
Note: The choice of grade depends on design requirements, thickness, and service temperature.
ASTM A516/A516M
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II. Available Steel Plate Grades Under ASTM A516/A516M Standard
The ASTM A516/A516M standard offers four grades with different strength levels. The choice of grade depends on design requirements, thickness, and service temperature.
III. Standard Core Positioning and Scope of Application of ASTM A516/A516M
The purpose of ASTM A516/A516M is to provide weldable carbon steel materials with low-temperature impact toughness for pressure vessels, addressing the issue of brittleness and fracture in ordinary carbon steels at low temperatures.
Applicable Equipment: Pressure-bearing equipment such as petroleum refining towers, chemical reactors, natural gas storage tanks, power station boiler drums, heat exchangers, etc.
Temperature Range: The standard service temperature ranges from -46°C to 454°C (depending on the steel grade; for example, A516 Gr.70 can be used as low as -46°C).
Thickness Limitations: The maximum thickness is typically 200mm (special requirements can be negotiated), while width and length can be customized according to manufacturing needs.
Notch Toughness: This is a key feature. The steel is produced to have a guaranteed ability to absorb energy and resist brittle fracture at its designated minimum service temperature. This is verified through Charpy V-Notch (CVN) impact testing.
Weldability: ASTM A516/A516M steel is known for its excellent weldability, which is critical for the fabrication of large pressure vessels.
IV. Key Technical Requirements of ASTM A516/A516M
ASTM A516/A516M imposes strict regulations on the chemical composition, mechanical properties, heat treatment, and non-destructive testing of materials to ensure their reliability.
1. Chemical Composition
Element
Composition (%)
Grade 55
Grade 60
Grade 65
Grade 70
Carbon (C) ½ in. [12.5 mm] and under
≤ 0.18
≤ 0.21
≤ 0.24
≤ 0.27
Manganese (Mn) ½ in. [12.5 mm] and under
0.60 - 0.90
0.60 - 0.90
0.85 - 1.20
0.85 - 1.20
Phosphorus (P)
≤ 0.025
≤ 0.025
≤ 0.025
≤ 0.025
Sulfur (S)
≤ 0.025
≤ 0.025
≤ 0.025
≤ 0.025
Silicon (Si)
0.15 - 0.40
0.15 - 0.40
0.15 - 0.40
0.15 - 0.40
Note: The steel must be fully "killed" (deoxidized), usually with silicon, which results in a more uniform chemical composition and mechanical properties.
2. Mechanical Properties
Key Metrics
Grade 55
Grade 60
Grade 65
Grade 70
Yield Strength, min, ksi [MPa]
30 [205]
32 [220]
35 [240]
38 [260]
Tensile Strength, ksi [MPa]
55-75 [380-515]
60-80 [415-550]
65-85 [450-585]
70-90 [485-620]
Elongation, in 2 in. [50 mm], min, %
27
25
23
21
Note:Notch Toughness (Impact Testing) is a critical requirement for A516. The material must meet Charpy V-Notch (CVN) impact energy requirements.
The required impact energy is not a fixed value in the base specification. It is determined by the service temperature specified by the purchaser. The test is conducted at a temperature either at or below the Minimum Design Metal Temperature (MDMT).
3. Heat Treatment Process
The heat treatment methods for ASTM A516 directly influence its performance, primarily including:
Normalizing: The steel plate is heated above the critical point (approximately 890°C–950°C), held at that temperature, and then air-cooled. This refines the grain structure, homogenizes the microstructure, and improves toughness (mandatory for Grade "N" steel).
Controlled Rolling: This process involves controlling the rolling temperature and deformation to partially replicate the effects of normalizing. It is typically applied to medium and thin specification steel plates.
Annealing: Used only for specific requirements, this process reduces hardness and improves machinability.
4. Nondestructive Testing (NDT)
To ensure internal quality, steel plates must undergo:
Ultrasonic Testing (UT): Conducted according to ASTM A609 standards, classified as Level Ⅰ (general requirements) and Level Ⅱ (strict requirements, such as for nuclear-grade equipment), to detect internal defects like delamination and inclusions in steel plates.
Surface Testing: Additional Magnetic Particle Testing (MT) or Penetrant Testing (PT) can be applied as needed to identify surface cracks.
V. Precautions for Procurement and Application
Clearly Specify Additional Requirements: During procurement, indicate the steel grade (e.g., A516Gr70), heat treatment condition (e.g., N), impact test temperature (e.g., -46°C), non-destructive testing level (e.g., UT Level II), and dimensional tolerances.
Welding Compatibility: Welding materials must match the composition and strength of A516. For example, use E7018 electrodes (corresponding to A516Gr70) and control welding heat input to avoid embrittlement in the heat-affected zone.
Certification Requirements: Suppliers must provide a "Material Test Report (MTR)" as required by ASTM standards, including chemical composition, mechanical properties, heat treatment records, and non-destructive testing results to ensure traceability.
ASTM A516 is the "benchmark standard" for carbon steel used in pressure vessels. Its core advantage lies in addressing safety risks in medium-to-low temperature pressure equipment through stringent composition control, heat treatment, and impact toughness requirements. When selecting this material, it is essential to appropriately match the steel grade and additional requirements based on the equipment's pressure, temperature, and load conditions, while ensuring compliance in procurement channels and traceability of the material.
Purpose: Carbon steel plate for pressure vessels requiring good notch toughness.
Most Common Grade: Grade 70 (U.S.) / Grade 485 (Metric).
Condition: Often supplied Normalized for enhanced properties.
Notation: The "/M" means it can be supplied to metric (A516M) or U.S. customary (A516) units.
Note:When ordering or specifying this material, it is crucial to state the full requirement, for example: "ASTM A516 Grade 70, Normalized, CVN tested at -30°C".